Provided by: haproxy_2.0.5-1_amd64 bug

NAME

       haproxy-lua - haproxy-lua Documentation

HAPROXY LUA RUNNING CONTEXTS

       The  Lua  code  executed in HAProxy can be processed in 2 main modes. The first one is the
       initialisation mode, and the second is the runtime mode.

       · In the initialisation mode, we can perform DNS solves, but we cannot perform socket I/O.
         In  this  initialisation  mode,  HAProxy  still  blocked during the execution of the Lua
         program.

       · In the runtime mode, we cannot  perform  DNS  solves,  but  we  can  use  sockets.   The
         execution  of  the Lua code is multiplexed with the requests processing, so the Lua code
         seems to be run in blocking, but it is not the case.

       The Lua code is loaded in one or more files. These files contains main code and functions.
       Lua have 6 execution context.

       1. The  Lua  file  body  context.  It  is  executed during the load of the Lua file in the
          HAProxy [global] section with the directive lua-load. It is executed in  initialisation
          mode. This section is use for configuring Lua bindings in HAProxy.

       2. The  Lua  init  context.  It  is  a  Lua  function  executed  just  after  the  HAProxy
          configuration parsing. The execution is in initialisation mode.  In  this  context  the
          HAProxy  environment  are  already initialized. It is useful to check configuration, or
          initializing socket connections or tasks. These functions  are  declared  in  the  body
          context  with the Lua function core.register_init(). The prototype of the function is a
          simple function without return value and without parameters, like this: function fcn().

       3. The Lua task context. It is a Lua function executed after  the  start  of  the  HAProxy
          scheduler,  and  just  after  the  declaration  of  the  task  with  the  Lua  function
          core.register_task(). This context can be concurrent with the traffic processing. It is
          executed  in  runtime  mode. The prototype of the function is a simple function without
          return value and without parameters, like this: function fcn().

       4. The action context. It is a Lua function  conditionally  executed.  These  actions  are
          registered  by  the  Lua  directives "core.register_action()". The prototype of the Lua
          called function is a function with doesn't returns anything and that take an object  of
          class TXN as entry. function fcn(txn).

       5. The  sample-fetch  context.  This  function  takes  a  TXN object as entry argument and
          returns a string. These types of function cannot execute any  blocking  function.  They
          are  useful to aggregate some of original HAProxy sample-fetches and return the result.
          The prototype of the function is function  string  fcn(txn).  These  functions  can  be
          registered with the Lua function core.register_fetches(). Each declared sample-fetch is
          prefixed by the string "lua.".

          NOTE: It is possible that this function cannot found the required data in the  original
          HAProxy sample-fetches, in this case, it cannot return the result. This case is not yet
          supported

       6. The converter context. It is a Lua function that takes a string as  input  and  returns
          another  string  as  output. These types of function are stateless, it cannot access to
          any context. They don't execute any blocking function.  The call prototype is  function
          string   fcn(string).   This   function   can  be  registered  with  the  Lua  function
          core.register_converters(). Each declared converter is prefixed by the string "lua.".

HAPROXY LUA HELLO WORLD

       HAProxy configuration file (hello_world.conf):

          global
             lua-load hello_world.lua

          listen proxy
             bind 127.0.0.1:10001
             tcp-request inspect-delay 1s
             tcp-request content use-service lua.hello_world

       HAProxy Lua file (hello_world.lua):

          core.register_service("hello_world", "tcp", function(applet)
             applet:send("hello world\n")
          end)

       How to start HAProxy for testing this configuration:

          ./haproxy -f hello_world.conf

       On other terminal, you can test with telnet:

          #:~ telnet 127.0.0.1 10001
          hello world

       class core()
              The "core" class contains all the HAProxy core functions. These function are useful
              for the controlling the execution flow, registering hooks, manipulating global maps
              or ACL, ...

              "core" class is basically provided with HAProxy. No require  line  is  required  to
              uses these function.

              The "core" class is static, it is not possible to create a new object of this type.

       core.emerg

              Returns
                     integer

              This  attribute  is  an  integer, it contains the value of the loglevel "emergency"
              (0).

       core.alert

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "alert" (1).

       core.crit

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "critical" (2).

       core.err

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "error" (3).

       core.warning

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "warning" (4).

       core.notice

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "notice" (5).

       core.info

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "info" (6).

       core.debug

              Returns
                     integer

              This attribute is an integer, it contains the value of the loglevel "debug" (7).

       core.proxies
              context: task, action, sample-fetch, converter

              This attribute is a table of declared proxies (frontend and backends).  Each  proxy
              give  an access to his list of listeners and servers. The table is indexed by proxy
              name, and each entry is of type Proxy class.

              Warning, if you are declared frontend and backend with the same name, only  one  of
              these are listed.

              See    core.backends

              See    core.frontends

       core.backends
              context: task, action, sample-fetch, converter

              This  attribute  is a table of declared proxies with backend capability. Each proxy
              give an access to his list of listeners and servers. The table is  indexed  by  the
              backend name, and each entry is of type Proxy class.

              See    core.proxies

              See    core.frontends

       core.frontends
              context: task, action, sample-fetch, converter

              This  attribute is a table of declared proxies with frontend capability. Each proxy
              give an access to his list of listeners and servers. The table is  indexed  by  the
              frontend name, and each entry is of type Proxy class.

              See    core.proxies

              See    core.backends

       core.log(loglevel, msg)
              context: body, init, task, action, sample-fetch, converter

              This   function  sends  a  log.  The  log  is  sent,  according  with  the  HAProxy
              configuration file, on the default syslog server if it is  configured  and  on  the
              stderr if it is allowed.

              Arguments

                     · loglevel  (integer) -- Is the log level associated with the message. It is
                       a number between 0 and 7.

                     · msg (string) -- The log content.

              See    core.emerg,  core.alert,  core.crit,  core.err,  core.warning,  core.notice,
                     core.info, core.debug (log level definitions)

              See    core.Debug()

              See    core.Info()

              See    core.Warning()

              See    core.Alert()

       core.Debug(msg)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · msg (string) -- The log content.

              See    core.log()

              Does the same job than:

          function Debug(msg)
            core.log(core.debug, msg)
          end

       core.Info(msg)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · msg (string) -- The log content.

              See    core.log()

          function Info(msg)
            core.log(core.info, msg)
          end

       core.Warning(msg)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · msg (string) -- The log content.

              See    core.log()

          function Warning(msg)
            core.log(core.warning, msg)
          end

       core.Alert(msg)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · msg (string) -- The log content.

              See    core.log()

          function Alert(msg)
            core.log(core.alert, msg)
          end

       core.add_acl(filename, key)
              context: init, task, action, sample-fetch, converter

              Add the ACL key in the ACLs list referenced by the file filename.

              Arguments

                     · filename (string) -- the filename that reference the ACL entries.

                     · key (string) -- the key which will be added.

       core.del_acl(filename, key)
              context: init, task, action, sample-fetch, converter

              Delete  the  ACL  entry referenced by the key key in the list of ACLs referenced by
              filename.

              Arguments

                     · filename (string) -- the filename that reference the ACL entries.

                     · key (string) -- the key which will be deleted.

       core.del_map(filename, key)
              context: init, task, action, sample-fetch, converter

              Delete the map entry indexed with the specified key in the list of maps  referenced
              by his filename.

              Arguments

                     · filename (string) -- the filename that reference the map entries.

                     · key (string) -- the key which will be deleted.

       core.get_info()
              context: body, init, task, action, sample-fetch, converter

              Returns  HAProxy  core  informations. We can found information like the uptime, the
              pid, memory pool usage, tasks number, ...

              These information are also returned by the management socket via the command  "show
              info".  See  the  management  socket  documentation  for more information about the
              content of these variables.

              Returns
                     an array of values.

       core.now()
              context: body, init, task, action

              This function returns the current time. The time returned is fixed by  the  HAProxy
              core  and  assures  than  the  hour  will  be  monotonic  and  that the system call
              'gettimeofday' will not be called too. The  time  is  refreshed  between  each  Lua
              execution  or  resume,  so two consecutive call to the function "now" will probably
              returns the same result.

              Returns
                     a table which contains two entries "sec"  and  "usec".  "sec"  contains  the
                     current at the epoch format, and "usec" contains the current microseconds.

       core.http_date(date)
              context: body, init, task, action

              This  function  take  a  string  representing  http  date,  and  returns an integer
              containing the corresponding date with a epoch format. A valid http date me respect
              the format IMF, RFC850 or ASCTIME.

              Arguments

                     · date (string) -- a date http-date formatted

              Returns
                     integer containing epoch date

              See    core.imf_date().

              See    core.rfc850_date().

              See    core.asctime_date().

              See    https://tools.ietf.org/html/rfc7231#section-7.1.1.1

       core.imf_date(date)
              context: body, init, task, action

              This  function  take  a  string  representing  IMF  date,  and  returns  an integer
              containing the corresponding date with a epoch format.

              Arguments

                     · date (string) -- a date IMF formatted

              Returns
                     integer containing epoch date

              See    https://tools.ietf.org/html/rfc7231#section-7.1.1.1

              The IMF format is like this:

          Sun, 06 Nov 1994 08:49:37 GMT

       core.rfc850_date(date)
              context: body, init, task, action

              This function take a string  representing  RFC850  date,  and  returns  an  integer
              containing the corresponding date with a epoch format.

              Arguments

                     · date (string) -- a date RFC859 formatted

              Returns
                     integer containing epoch date

              See    https://tools.ietf.org/html/rfc7231#section-7.1.1.1

              The RFC850 format is like this:

          Sunday, 06-Nov-94 08:49:37 GMT

       core.asctime_date(date)
              context: body, init, task, action

              This  function  take  a  string  representing  ASCTIME date, and returns an integer
              containing the corresponding date with a epoch format.

              Arguments

                     · date (string) -- a date ASCTIME formatted

              Returns
                     integer containing epoch date

              See    https://tools.ietf.org/html/rfc7231#section-7.1.1.1

              The ASCTIME format is like this:

          Sun Nov  6 08:49:37 1994

       core.rfc850_date(date)
              context: body, init, task, action

              This function take  a  string  representing  http  date,  and  returns  an  integer
              containing the corresponding date with a epoch format.

              Arguments

                     · date (string) -- a date http-date formatted

       core.asctime_date(date)
              context: body, init, task, action

              This  function  take  a  string  representing  http  date,  and  returns an integer
              containing the corresponding date with a epoch format.

              Arguments

                     · date (string) -- a date http-date formatted

       core.msleep(milliseconds)
              context: body, init, task, action

              The core.msleep() stops the Lua execution between specified milliseconds.

              Arguments

                     · milliseconds (integer) -- the required milliseconds.

       core.proxies
              context: body, init, task, action, sample-fetch, converter

              Proxies is a table containing the list of all proxies declared in the configuration
              file.  The  table is indexed by the proxy name, and each entry of the proxies table
              is an object of type Proxy class.

              Warning, if you have declared a frontend and backend with the same name,  only  one
              of these are listed.

       core.register_action(name, actions, func[, nb_args])
              context: body

              Register  a  Lua function executed as action. All the registered action can be used
              in HAProxy with the prefix "lua.". An action gets a TXN object class as input.

              Arguments

                     · name (string) -- is the name of the converter.

                     · actions (table) -- is a table of string describing the HAProxy actions who
                       want  to  register  to.  The  expected  actions  are 'tcp-req', 'tcp-res',
                       'http-req' or 'http-res'.

                     · nb_args (integer) -- is the expected number of argument  for  the  action.
                       By default the value is 0.

                     · func (function) -- is the Lua function called to work as converter.

              The prototype of the Lua function used as argument is:

          function(txn [, arg1 [, arg2]])

          ·

            txn (TXN class): this is a TXN object used for manipulating the
                   current request or TCP stream.

          · argX: this is argument provided through the HAProxy configuration file.

          Here,  an  example of action registration. The action just send an 'Hello world' in the
          logs.

          core.register_action("hello-world", { "tcp-req", "http-req" }, function(txn)
             txn:Info("Hello world")
          end)
          This example code is used in HAproxy configuration like this:

          frontend tcp_frt
            mode tcp
            tcp-request content lua.hello-world

          frontend http_frt
            mode http
            http-request lua.hello-world
          A second example using arguments

          function hello_world(txn, arg)
             txn:Info("Hello world for " .. arg)
          end
          core.register_action("hello-world", { "tcp-req", "http-req" }, hello_world, 2)
          This example code is used in HAproxy configuration like this:

          frontend tcp_frt
            mode tcp
            tcp-request content lua.hello-world everybody

       core.register_converters(name, func)
              context: body

              Register a Lua function executed as converter. All the registered converters can be
              used  in  HAProxy  with  the  prefix "lua.". An converter get a string as input and
              return a string as output. The registered function can  take  up  to  9  values  as
              parameter. All the value are strings.

              Arguments

                     · name (string) -- is the name of the converter.

                     · func (function) -- is the Lua function called to work as converter.

              The prototype of the Lua function used as argument is:

          function(str, [p1 [, p2 [, ... [, p5]]]])

          · str (string): this is the input value automatically converted in string.

          · p1  ..  p5  (string):  this  is  a  list  of string arguments declared in the HAProxy
            configuration file. The number of arguments doesn't exceed  5.   The  order  and  the
            nature of these is conventionally choose by the developer.

       core.register_fetches(name, func)
              context: body

              Register  a  Lua function executed as sample fetch. All the registered sample fetch
              can be used in HAProxy with the prefix "lua.". A Lua sample fetch return  a  string
              as  output.  The  registered function can take up to 9 values as parameter. All the
              value are strings.

              Arguments

                     · name (string) -- is the name of the converter.

                     · func (function) -- is the Lua function called to work as sample fetch.

              The prototype of the Lua function used as argument is:

          string function(txn, [p1 [, p2 [, ... [, p5]]]])

          · txn (TXN class): this is the txn object associated with the current request.

          · p1 .. p5 (string): this is a  list  of  string  arguments  declared  in  the  HAProxy
            configuration  file.  The  number  of  arguments doesn't exceed 5.  The order and the
            nature of these is conventionally choose by the developer.

          · Returns: A string containing some data, or nil if the value cannot be returned now.

          lua example code:

          core.register_fetches("hello", function(txn)
              return "hello"
          end)
          HAProxy example configuration:

          frontend example
             http-request redirect location /%[lua.hello]

       core.register_service(name, mode, func)
              context: body

              Register a Lua function executed as a service. All the registered  service  can  be
              used  in  HAProxy  with  the prefix "lua.". A service gets an object class as input
              according with the required mode.

              Arguments

                     · name (string) -- is the name of the converter.

                     · mode (string) -- is string describing the required  mode.  Only  'tcp'  or
                       'http' are allowed.

                     · func (function) -- is the Lua function called to work as converter.

              The prototype of the Lua function used as argument is:

          function(applet)

          · applet  applet   will be a AppletTCP class or a AppletHTTP class. It depends the type
            of registered applet. An applet  registered  with  the  'http'  value  for  the  mode
            parameter  will  gets a AppletHTTP class. If the mode value is 'tcp', the applet will
            gets a AppletTCP class.

          warning: Applets of type 'http' cannot be called from 'tcp-' rulesets. Only the 'http-'
          rulesets  are authorized, this means that is not possible to call an HTTP applet from a
          proxy in tcp mode. Applets of type 'tcp' can be called from anywhere.

          Here, an example of service registration. The service just send an 'Hello world' as  an
          http response.

          core.register_service("hello-world", "http", function(applet)
             local response = "Hello World !"
             applet:set_status(200)
             applet:add_header("content-length", string.len(response))
             applet:add_header("content-type", "text/plain")
             applet:start_response()
             applet:send(response)
          end)
          This example code is used in HAproxy configuration like this:

          frontend example
             http-request use-service lua.hello-world

       core.register_init(func)
              context: body

              Register  a  function  executed  after the configuration parsing. This is useful to
              check any parameters.

              Arguments

                     · func (function) -- is the Lua function called to work as initializer.

              The prototype of the Lua function used as argument is:

          function()
          It takes no input, and no output is expected.

       core.register_task(func)
              context: body, init, task, action, sample-fetch, converter

              Register and start independent task. The task is  started  when  the  HAProxy  main
              scheduler starts. For example this type of tasks can be executed to perform complex
              health checks.

              Arguments

                     · func (function) -- is the Lua function called to work as initializer.

              The prototype of the Lua function used as argument is:

          function()
          It takes no input, and no output is expected.

       core.register_cli([path], usage, func)
              context: body

              Register and start independent task. The task is  started  when  the  HAProxy  main
              scheduler starts. For example this type of tasks can be executed to perform complex
              health checks.

              Arguments

                     · path (array) -- is the sequence of word for which the cli execute the  Lua
                       binding.

                     · usage (string) -- is the usage message displayed in the help.

                     · func (function) -- is the Lua function called to handle the CLI commands.

              The prototype of the Lua function used as argument is:

          function(AppletTCP, [arg1, [arg2, [...]]])
          I/O  are managed with the AppletTCP class object. Args are given as parameter. The args
          embed the registered path. If the path is declared like this:

          core.register_cli({"show", "ssl", "stats"}, "Display SSL stats..", function(applet, arg1, arg2, arg3, arg4, arg5)
               end)
          And we execute this in the prompt:

          > prompt
          > show ssl stats all
          Then, arg1, arg2 and arg3 will contains respectively "show", "ssl" and  "stats".   arg4
          will contain "all". arg5 contains nil.

       core.set_nice(nice)
              context: task, action, sample-fetch, converter

              Change the nice of the current task or current session.

              Arguments

                     · nice (integer) -- the nice value, it must be between -1024 and 1024.

       core.set_map(filename, key, value)
              context: init, task, action, sample-fetch, converter

              Set the value value associated to the key key in the map referenced by filename.

              Arguments

                     · filename (string) -- the Map reference

                     · key (string) -- the key to set or replace

                     · value (string) -- the associated value

       core.sleep(int seconds)
              context: body, init, task, action

              The core.sleep() functions stop the Lua execution between specified seconds.

              Arguments

                     · seconds (integer) -- the required seconds.

       core.tcp()
              context: init, task, action

              This function returns a new object of a socket class.

              Returns
                     A Socket class object.

       core.concat()
              context: body, init, task, action, sample-fetch, converter

              This function returns a new concat object.

              Returns
                     A Concat class object.

       core.done(data)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · data  (any)  --  Return  some  data  for  the  caller.  It  is useful with
                       sample-fetches and sample-converters.

              Immediately stops the current Lua execution and returns to the caller which may  be
              a  sample  fetch, a converter or an action and returns the specified value (ignored
              for actions). It is used when the LUA process finishes its work and wants  to  give
              back the control to HAProxy without executing the remaining code. It can be seen as
              a multi-level "return".

       core.yield()
              context: task, action, sample-fetch, converter

              Give back the hand at the HAProxy scheduler. It is used  when  the  LUA  processing
              consumes a lot of processing time.

       core.parse_addr(address)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · network  --  is a string describing an ipv4 or ipv6 address and optionally
                       its network length, like this: "127.0.0.1/8" or "aaaa::1234/32".

              Returns
                     a userdata containing network or nil if an error occurs.

              Parse ipv4 or ipv6 addresses and its facultative associated network.

       core.match_addr(addr1, addr2)
              context: body, init, task, action, sample-fetch, converter

              Arguments

                     · addr1 -- is an address created with "core.parse_addr".

                     · addr2 -- is an address created with "core.parse_addr".

              Returns
                     boolean, true if the network of the addresses match, else returns false.

              Match two networks. For example "127.0.0.1/32" matchs "127.0.0.0/8". The  order  of
              network is not important.

       core.tokenize(str, separators[, noblank])
              context: body, init, task, action, sample-fetch, converter

              This  function  is  useful  for  tokenizing  an  entry, or splitting some messages.
              :param string str: The string which will be split.   :param  string  separators:  A
              string  containing  a  list  of  separators.   :param boolean noblank: Ignore empty
              entries.  :returns: an array of string.

              For example:

          local array = core.tokenize("This function is useful, for tokenizing an entry.", "., ", true)
          print_r(array)
          Returns this array:

          (table) table: 0x21c01e0 [
              1: (string) "This"
              2: (string) "function"
              3: (string) "is"
              4: (string) "useful"
              5: (string) "for"
              6: (string) "tokenizing"
              7: (string) "an"
              8: (string) "entry"
          ]

       class Proxy()
              This class provides a way for manipulating proxy and  retrieving  information  like
              statistics.

       Proxy.name
              Contain the name of the proxy.

       Proxy.uuid
              Contain the unique identifier of the proxy.

       Proxy.servers
              Contain a table with the attached servers. The table is indexed by server name, and
              each server entry is an object of type Server class.

       Proxy.stktable
              Contains a stick table object attached to the proxy.

       Proxy.listeners
              Contain a table with the attached listeners. The table is indexed by listener name,
              and each each listeners entry is an object of type Listener class.

       Proxy.pause(px)
              Pause the proxy. See the management socket documentation for more information.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

       Proxy.resume(px)
              Resume the proxy. See the management socket documentation for more information.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

       Proxy.stop(px)
              Stop the proxy. See the management socket documentation for more information.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

       Proxy.shut_bcksess(px)
              Kill   the  session  attached  to  a  backup  server.  See  the  management  socket
              documentation for more information.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

       Proxy.get_cap(px)
              Returns a string describing the capabilities of the proxy.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

              Returns
                     a string "frontend", "backend", "proxy" or "ruleset".

       Proxy.get_mode(px)
              Returns a string describing the mode of the current proxy.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

              Returns
                     a string "tcp", "http", "health" or "unknown"

       Proxy.get_stats(px)
              Returns a table containing the proxy statistics. The statistics  returned  are  not
              the same if the proxy is frontend or a backend.

              Arguments

                     · px (class_proxy) -- A Proxy class which indicates the manipulated proxy.

              Returns
                     a key/value table containing stats

       class Server()
              This class provides a way for manipulating servers and retrieving information.

       Server.name
              Contain the name of the server.

       Server.puid
              Contain the proxy unique identifier of the server.

       Server.is_draining(sv)
              Return true if the server is currently draining sticky connections.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

              Returns
                     a boolean

       Server.set_maxconn(sv, weight)
              Dynamically change the maximum connections of the server. See the management socket
              documentation for more information about the format of the string.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

                     · maxconn (string) -- A string describing the server maximum connections.

       Server.get_maxconn(sv, weight)
              This function returns an integer representing the server maximum connections.

              Arguments

                     · sv (class_server) --  A  Server  class  which  indicates  the  manipulated
                       server.

              Returns
                     an integer.

       Server.set_weight(sv, weight)
              Dynamically   change   the   weight  of  the  server.  See  the  management  socket
              documentation for more information about the format of the string.

              Arguments

                     · sv (class_server) --  A  Server  class  which  indicates  the  manipulated
                       server.

                     · weight (string) -- A string describing the server weight.

       Server.get_weight(sv)
              This function returns an integer representing the server weight.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

              Returns
                     an integer.

       Server.set_addr(sv, addr)
              Dynamically  change  the  address  of  the  server.  See  the   management   socket
              documentation for more information about the format of the string.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

                     · addr (string) -- A string describing the server address.

       Server.get_addr(sv)
              Returns a string describing the address of the server.

              Arguments

                     · sv (class_server) --  A  Server  class  which  indicates  the  manipulated
                       server.

              Returns
                     A string

       Server.get_stats(sv)
              Returns server statistics.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

              Returns
                     a key/value table containing stats

       Server.shut_sess(sv)
              Shutdown all the sessions  attached  to  the  server.  See  the  management  socket
              documentation for more information about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.set_drain(sv)
              Drain sticky sessions. See the management socket documentation for more information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.set_maint(sv)
              Set maintenance mode. See the management socket documentation for more  information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.set_ready(sv)
              Set normal mode. See the management socket documentation for more information about
              this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.check_enable(sv)
              Enable health checks. See the management socket documentation for more  information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.check_disable(sv)
              Disable health checks. See the management socket documentation for more information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.check_force_up(sv)
              Force health-check up. See the management socket documentation for more information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.check_force_nolb(sv)
              Force health-check nolb mode. See the  management  socket  documentation  for  more
              information about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.check_force_down(sv)
              Force  health-check  down.  See  the  management  socket  documentation  for   more
              information about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.agent_enable(sv)
              Enable agent check. See the management socket documentation  for  more  information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.agent_disable(sv)
              Disable agent check. See the management socket documentation for  more  information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.agent_force_up(sv)
              Force agent check up. See the management socket documentation for more  information
              about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Server.agent_force_down(sv)
              Force  agent  check  down.  See  the  management  socket  documentation  for   more
              information about this function.

              Arguments

                     · sv  (class_server)  --  A  Server  class  which  indicates the manipulated
                       server.

       Listener.get_stats(ls)
              Returns server statistics.

              Arguments

                     · ls (class_listener) -- A Listener class which  indicates  the  manipulated
                       listener.

              Returns
                     a key/value table containing stats

       class Concat()
              This  class  provides a fast way for string concatenation. The way using native Lua
              concatenation like the code below is slow for some reasons.

          str = "string1"
          str = str .. ", string2"
          str = str .. ", string3"
          For each concatenation, Lua: * allocate memory for  the  result,  *  catenate  the  two
          string  copying  the  strings  in  the  new  memory  bloc,  * free the old memory block
          containing the string which is no longer used.  This process  does  many  memory  move,
          allocation  and free. In addition, the memory is not really freed, it is just mark mark
          as unused and wait for the garbage collector.

          The Concat class provide an  alternative  way  to  concatenate  strings.  It  uses  the
          internal Lua mechanism (it does not allocate memory), but it doesn't copy the data more
          than once.

          On my computer, the following loops spends 0.2s for the Concat method and 18.5s for the
          pure  Lua  implementation. So, the Concat class is about 1000x faster than the embedded
          solution.

          for j = 1, 100 do
            c = core.concat()
            for i = 1, 20000 do
              c:add("#####")
            end
          end

          for j = 1, 100 do
            c = ""
            for i = 1, 20000 do
              c = c .. "#####"
            end
          end

       Concat.add(concat, string)
              This function adds a string to the current concatenated string.

              Arguments

                     · concat (class_concat) -- A  Concat  class  which  contains  the  currently
                       builded string.

                     · string  (string)  --  A  new  string  to  concatenate to the current built
                       string.

       Concat.dump(concat)
              This function returns the concatenated string.

              Arguments

                     · concat (class_concat) -- A  Concat  class  which  contains  the  currently
                       builded string.

              Returns
                     the concatenated string

       class Fetches()
              This  class  contains  a  lot  of  internal HAProxy sample fetches. See the HAProxy
              "configuration.txt" documentation for more information about her  usage.  They  are
              the chapters 7.3.2 to 7.3.6.

              warning  some  sample  fetches are not available in some context. These limitations
              are specified in this documentation when they're useful.

              See    TXN.f

              See    TXN.sf

              Fetches are useful for:

              · get system time,

              · get environment variable,

              · get random numbers,

              · known backend status like  the  number  of  users  in  queue  or  the  number  of
                connections established,

              · client information like ip source or destination,

              · deal with stick tables,

              · Established SSL informations,

              · HTTP information like headers or method.

          function action(txn)
            -- Get source IP
            local clientip = txn.f:src()
          end

       class Converters()
              This  class  contains  a lot of internal HAProxy sample converters. See the HAProxy
              documentation "configuration.txt" for more information about  her  usage.  Its  the
              chapter 7.3.1.

              See    TXN.c

              See    TXN.sc

              Converters provides statefull transformation. They are useful for:

              · converting input to base64,

              · applying hash on input string (djb2, crc32, sdbm, wt6),

              · format date,

              · json escape,

              · extracting preferred language comparing two lists,

              · turn to lower or upper chars,

              · deal with stick tables.

       class Channel()
              HAProxy  uses two buffers for the processing of the requests. The first one is used
              with the request data (from the client to the server) and the second  is  used  for
              the response data (from the server to the client).

              Each buffer contains two types of data. The first type is the incoming data waiting
              for a processing. The second part is the outgoing data already processed.  Usually,
              the incoming data is processed, after it is tagged as outgoing data, and finally it
              is sent. The following functions provides tools for manipulating these  data  in  a
              buffer.

              The following diagram shows where the channel class function are applied.

              Warning:  It is not possible to read from the response in request action, and it is
              not possible to read for the request channel in response action.
       [image]

       Channel.dup(channel)
              This function returns a string that contain the entire  buffer.  The  data  is  not
              remove from the buffer and can be reprocessed later.

              If the buffer cant receive more data, a 'nil' value is returned.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

              Returns
                     a string containing all the available data or nil.

       Channel.get(channel)
              This function returns a string that contain the entire buffer. The data is consumed
              from the buffer.

              If the buffer cant receive more data, a 'nil' value is returned.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

              Returns
                     a string containing all the available data or nil.

       Channel.getline(channel)
              This function returns a string that contain the first line of the buffer. The  data
              is consumed. If the data returned doesn't contains a final 'n' its assumed than its
              the last available data in the buffer.

              If the buffer cant receive more data, a 'nil' value is returned.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

              Returns
                     a string containing the available line or nil.

       Channel.set(channel, string)
              This function replace the content of the buffer by the string. The function returns
              the copied length, otherwise, it returns -1.

              The  data  set  with  this  function are not send. They wait for the end of HAProxy
              processing, so the buffer can be full.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

                     · string (string) -- The data which will sent.

              Returns
                     an integer containing the amount of bytes copied or -1.

       Channel.append(channel, string)
              This function append the string argument to the content of the buffer. The function
              returns the copied length, otherwise, it returns -1.

              The  data  set  with  this  function are not send. They wait for the end of HAProxy
              processing, so the buffer can be full.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

                     · string (string) -- The data which will sent.

              Returns
                     an integer containing the amount of bytes copied or -1.

       Channel.send(channel, string)
              This function required immediate send of the data.  Unless  if  the  connection  is
              close, the buffer is regularly flushed and all the string can be sent.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

                     · string (string) -- The data which will sent.

              Returns
                     an integer containing the amount of bytes copied or -1.

       Channel.get_in_length(channel)
              This function returns the length of the input part of the buffer.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

              Returns
                     an integer containing the amount of available bytes.

       Channel.get_out_length(channel)
              This function returns the length of the output part of the buffer.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

              Returns
                     an integer containing the amount of available bytes.

       Channel.forward(channel, int)
              This function transfer bytes from the input part of the buffer to the output part.

              Arguments

                     · channel (class_channel) -- The manipulated Channel.

                     · int (integer) -- The amount of data which will be forwarded.

       Channel.is_full(channel)
              This function returns true if the buffer channel is full.

              Returns
                     a boolean

       class HTTP()
              This class contain all the HTTP manipulation functions.

       HTTP.req_get_headers(http)
              Returns a table containing all the request headers.

              Arguments

                     · http (class_http) -- The related http object.

              Returns
                     table of headers.

              See    HTTP.res_get_headers()

              This is the form of the returned table:

          HTTP:req_get_headers()['<header-name>'][<header-index>] = "<header-value>"

          local hdr = HTTP:req_get_headers()
          hdr["host"][0] = "www.test.com"
          hdr["accept"][0] = "audio/basic q=1"
          hdr["accept"][1] = "audio/*, q=0.2"
          hdr["accept"][2] = "*/*, q=0.1"

       HTTP.res_get_headers(http)
              Returns a table containing all the response headers.

              Arguments

                     · http (class_http) -- The related http object.

              Returns
                     table of headers.

              See    HTTP.req_get_headers()

              This is the form of the returned table:

          HTTP:res_get_headers()['<header-name>'][<header-index>] = "<header-value>"

          local hdr = HTTP:req_get_headers()
          hdr["host"][0] = "www.test.com"
          hdr["accept"][0] = "audio/basic q=1"
          hdr["accept"][1] = "audio/*, q=0.2"
          hdr["accept"][2] = "*.*, q=0.1"

       HTTP.req_add_header(http, name, value)
              Appends  an  HTTP header field in the request whose name is specified in "name" and
              whose value is defined in "value".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · value (string) -- The header value.

              See    HTTP.res_add_header()

       HTTP.res_add_header(http, name, value)
              Appends an HTTP header field in the response whose name is specified in "name"  and
              whose value is defined in "value".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · value (string) -- The header value.

              See    HTTP.req_add_header()

       HTTP.req_del_header(http, name)
              Removes all HTTP header fields in the request whose name is specified in "name".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

              See    HTTP.res_del_header()

       HTTP.res_del_header(http, name)
              Removes all HTTP header fields in the response whose name is specified in "name".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

              See    HTTP.req_del_header()

       HTTP.req_set_header(http, name, value)
              This  variable  replace all occurrence of all header "name", by only one containing
              the "value".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · value (string) -- The header value.

              See    HTTP.res_set_header()

              This function does the same work as the following code:

          function fcn(txn)
             TXN.http:req_del_header("header")
             TXN.http:req_add_header("header", "value")
          end

       HTTP.res_set_header(http, name, value)
              This variable replace all occurrence of all header "name", by only  one  containing
              the "value".

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · value (string) -- The header value.

              See    HTTP.req_rep_header()

       HTTP.req_rep_header(http, name, regex, replace)
              Matches  the regular expression in all occurrences of header field "name" according
              to "regex", and replaces them with the "replace" argument.  The  replacement  value
              can contain back references like 1, 2, ... This function works with the request.

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · regex (string) -- The match regular expression.

                     · replace (string) -- The replacement value.

              See    HTTP.res_rep_header()

       HTTP.res_rep_header(http, name, regex, string)
              Matches  the regular expression in all occurrences of header field "name" according
              to "regex", and replaces them with the "replace" argument.  The  replacement  value
              can contain back references like 1, 2, ... This function works with the request.

              Arguments

                     · http (class_http) -- The related http object.

                     · name (string) -- The header name.

                     · regex (string) -- The match regular expression.

                     · replace (string) -- The replacement value.

              See    HTTP.req_rep_header()

       HTTP.req_set_method(http, method)
              Rewrites the request method with the parameter "method".

              Arguments

                     · http (class_http) -- The related http object.

                     · method (string) -- The new method.

       HTTP.req_set_path(http, path)
              Rewrites the request path with the "path" parameter.

              Arguments

                     · http (class_http) -- The related http object.

                     · path (string) -- The new path.

       HTTP.req_set_query(http, query)
              Rewrites  the  request's  query  string which appears after the first question mark
              ("?") with the parameter "query".

              Arguments

                     · http (class_http) -- The related http object.

                     · query (string) -- The new query.

       HTTP.req_set_uri(http, uri)
              Rewrites the request URI with the parameter "uri".

              Arguments

                     · http (class_http) -- The related http object.

                     · uri (string) -- The new uri.

       HTTP.res_set_status(http, status[, reason])
              Rewrites the response status code with the parameter "code".

              If no custom reason is provided, it will be generated from the status.

              Arguments

                     · http (class_http) -- The related http object.

                     · status (integer) -- The new response status code.

                     · reason (string) -- The new response reason (optional).

       class TXN()
              The txn class contain all the functions relative to the  http  or  tcp  transaction
              (Note than a tcp stream is the same than a tcp transaction, but an HTTP transaction
              is not the same than a tcp stream).

              The usage of this class permits to retrieve data from the requests,  alter  it  and
              forward it.

              All   the   functions   provided  by  this  class  are  available  in  the  context
              sample-fetches and actions.

       TXN.c

              Returns
                     An Converters class.

              This attribute contains a Converters class object.

       TXN.sc

              Returns
                     An Converters class.

              This attribute contains a Converters class object. The  functions  of  this  object
              returns always a string.

       TXN.f

              Returns
                     An Fetches class.

              This attribute contains a Fetches class object.

       TXN.sf

              Returns
                     An Fetches class.

              This  attribute  contains  a  Fetches  class  object.  The functions of this object
              returns always a string.

       TXN.req

              Returns
                     An Channel class.

              This attribute contains a channel class object for the request buffer.

       TXN.res

              Returns
                     An Channel class.

              This attribute contains a channel class object for the response buffer.

       TXN.http

              Returns
                     An HTTP class.

              This attribute contains an HTTP class object. It is available only if the proxy has
              the "mode http" enabled.

       TXN.log(TXN, loglevel, msg)
              This   function  sends  a  log.  The  log  is  sent,  according  with  the  HAProxy
              configuration file, on the default syslog server if it is  configured  and  on  the
              stderr if it is allowed.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · loglevel  (integer) -- Is the log level associated with the message. It is
                       a number between 0 and 7.

                     · msg (string) -- The log content.

              See    core.emerg,  core.alert,  core.crit,  core.err,  core.warning,  core.notice,
                     core.info, core.debug (log level definitions)

              See    TXN.deflog()

              See    TXN.Debug()

              See    TXN.Info()

              See    TXN.Warning()

              See    TXN.Alert()

       TXN.deflog(TXN, msg)
              Sends  a  log  line  with  the  default  loglevel for the proxy associated with the
              transaction.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · msg (string) -- The log content.

              See    :js:func:
                     `
                     TXN.log

       TXN.Debug(txn, msg)

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · msg (string) -- The log content.

              See    TXN.log()

              Does the same job than:

          function Debug(txn, msg)
            TXN.log(txn, core.debug, msg)
          end

       TXN.Info(txn, msg)

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · msg (string) -- The log content.

              See    TXN.log()

          function Debug(txn, msg)
            TXN.log(txn, core.info, msg)
          end

       TXN.Warning(txn, msg)

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · msg (string) -- The log content.

              See    TXN.log()

          function Debug(txn, msg)
            TXN.log(txn, core.warning, msg)
          end

       TXN.Alert(txn, msg)

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · msg (string) -- The log content.

              See    TXN.log()

          function Debug(txn, msg)
            TXN.log(txn, core.alert, msg)
          end

       TXN.get_priv(txn)
              Return Lua data  stored  in  the  current  transaction  (with  the  TXN.set_priv())
              function. If no data are stored, it returns a nil value.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

              Returns
                     the opaque data previously stored, or nil if nothing is available.

       TXN.set_priv(txn, data)
              Store  any  data  in  the  current HAProxy transaction. This action replace the old
              stored data.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · data (opaque) -- The data which is stored in the transaction.

       TXN.set_var(TXN, var, value)
              Converts a Lua type in a HAProxy type and store it in a variable <var>.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

                     · value  (type)  --  The  value  associated to the variable. The type can be
                       string or integer.

       TXN.unset_var(TXN, var)
              Unset the variable <var>.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

       TXN.get_var(TXN, var)
              Returns data stored in the variable <var> converter in Lua type.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · var  (string)  --  The  variable  name according with the HAProxy variable
                       syntax.

       TXN.done(txn)
              This function terminates processing of the transaction and the associated  session.
              It  can  be used when a critical error is detected or to terminate processing after
              some data have been returned to the client (eg: a redirect).

              Warning: It not make sense to call this function from sample-fetches. In this  case
              the  behaviour of this one is the same than core.done(): it quit the Lua execution.
              The transaction is really aborted only from an action registered function.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

       TXN.set_loglevel(txn, loglevel)
              Is used to change the log level of the current request. The "loglevel" must  be  an
              integer between 0 and 7.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · loglevel (integer) -- The required log level. This variable can be one of

              See    core.emerg,  core.alert,  core.crit,  core.err,  core.warning,  core.notice,
                     core.info, core.debug (log level definitions)

       TXN.set_tos(txn, tos)
              Is used to set the TOS or DSCP field value of packets sent to  the  client  to  the
              value passed in "tos" on platforms which support this.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · tos (integer) -- The new TOS os DSCP.

       TXN.set_mark(txn, mark)
              Is  used  to  set the Netfilter MARK on all packets sent to the client to the value
              passed in "mark" on platforms which support it.

              Arguments

                     · txn (class_txn) -- The class txn object containing the data.

                     · mark (integer) -- The mark value.

       TXN.set_priority_class(txn, prio)
              This function adjusts the priority class of the transaction. The  value  should  be
              within the range -2047..2047. Values outside this range will be truncated.

              See    the   HAProxy   configuration.txt   file   keyword   "http-request"   action
              "set-priority-class" for details.

       TXN.set_priority_offset(txn, prio)
              This function adjusts the priority offset of the transaction. The value  should  be
              within the range -524287..524287. Values outside this range will be truncated.

              See    the   HAProxy   configuration.txt   file   keyword   "http-request"   action
              "set-priority-offset" for details.

       class Socket()
              This class must be  compatible  with  the  Lua  Socket  class.  Only  the  'client'
              functions are available. See the Lua Socket documentation:

              http://w3.impa.br/~diego/software/luasocket/tcp.html

       Socket.close(socket)
              Closes a TCP object. The internal socket used by the object is closed and the local
              address to which the object was bound is made available to other  applications.  No
              further  operations (except for further calls to the close method) are allowed on a
              closed Socket.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

              Note: It is important to close all used sockets once they are not needed, since, in
              many  systems,  each  socket  uses  a  file  descriptor,  which  are limited system
              resources. Garbage-collected objects are automatically closed  before  destruction,
              though.

       Socket.connect(socket, address[, port])
              Attempts to connect a socket object to a remote host.

              In case of error, the method returns nil followed by a string describing the error.
              In case of success, the method returns 1.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

                     · address (string) -- can be an IP address or a host  name.  See  below  for
                       more information.

                     · port (integer) -- must be an integer number in the range [1..64K].

              Returns
                     1 or nil.

              An  address  field  extension  permits  to use the connect() function to connect to
              other stream than TCP. The syntax containing a simpleipv4 or ipv6  address  is  the
              basically expected format. This format requires the port.

              Other  format accepted are a socket path like "/socket/path", it permits to connect
              to a socket. Abstract namespaces are supported with the prefix "abns@", and finally
              a file descriptor can be passed with the prefix "fd@".  The prefix "ipv4@", "ipv6@"
              and "unix@" are also supported. The port can be passed int the string.  The  syntax
              "127.0.0.1:1234" is valid. In this case, the parameter port must not be set.

       Socket.connect_ssl(socket, address, port)
              Same behavior than the function socket:connect, but uses SSL.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

              Returns
                     1 or nil.

       Socket.getpeername(socket)
              Returns information about the remote side of a connected client object.

              Returns  a string with the IP address of the peer, followed by the port number that
              peer is using for the connection. In case of error, the method returns nil.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

              Returns
                     a string containing the server information.

       Socket.getsockname(socket)
              Returns the local address information associated to the object.

              The method returns a string with local IP address and a number with the  port.   In
              case of error, the method returns nil.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

              Returns
                     a string containing the client information.

       Socket.receive(socket[, pattern[, prefix]])
              Reads data from a client object, according to the specified read pattern.  Patterns
              follow the Lua file I/O format, and  the  difference  in  performance  between  all
              patterns is negligible.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

                     · pattern (string|integer) -- Describe what is required (see below).

                     · prefix (string) -- A string which will be prefix the returned data.

              Returns
                     a string containing the required data or nil.

              Pattern can be any of the following:

              ·

                `*a`: reads from the socket until the connection is closed. No
                       end-of-line translation is performed;

              ·

                `*l`: reads a line of text from the Socket. The line is terminated by a
                       LF character (ASCII 10), optionally preceded by a CR character (ASCII 13).
                       The CR and LF characters are not included in the returned line.  In  fact,
                       all CR characters are ignored by the pattern. This is the default pattern.

              ·

                number: causes the method to read a specified number of bytes from the
                       Socket.  Prefix  is an optional string to be concatenated to the beginning
                       of any received data before return.

              · empty: If the pattern is left empty, the default option is *l.

              If successful, the method returns the received  pattern.  In  case  of  error,  the
              method returns nil followed by an error message which can be the string 'closed' in
              case the connection was closed before the transmission was completed or the  string
              'timeout'  in  case there was a timeout during the operation. Also, after the error
              message, the function returns the partial result of the transmission.

              Important note: This function was changed severely. It  used  to  support  multiple
              patterns  (but  I  have  never  seen this feature used) and now it doesn't anymore.
              Partial results used to be returned in the same way  as  successful  results.  This
              last feature violated the idea that all functions should return nil on error.  Thus
              it was changed too.

       Socket.send(socket, data[, start[, end]])
              Sends data through client object.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

                     · data (string) -- The data that will be sent.

                     · start (integer) -- The start position in the buffer of the data which will
                       be sent.

                     · end  (integer) -- The end position in the buffer of the data which will be
                       sent.

              Returns
                     see below.

              Data is the string to be sent. The optional arguments i and j work exactly like the
              standard string.sub Lua function to allow the selection of a substring to be sent.

              If  successful,  the  method returns the index of the last byte within [start, end]
              that has been sent. Notice that, if start is 1 or absent, this is  effectively  the
              total  number  of bytes sent. In case of error, the method returns nil, followed by
              an error message, followed by the index of the last byte within [start,  end]  that
              has  been sent. You might want to try again from the byte following that. The error
              message can be 'closed' in case the connection was closed before  the  transmission
              was  completed  or  the  string  'timeout'  in  case there was a timeout during the
              operation.

              Note: Output is not buffered. For small strings, it is always better to concatenate
              them  in  Lua  (with  the '..' operator) and send the result in one call instead of
              calling the method several times.

       Socket.setoption(socket, option[, value])
              Just implemented for compatibility, this cal does nothing.

       Socket.settimeout(socket, value[, mode])
              Changes the timeout values for the object. All I/O operations are  blocking.   That
              is,  any  call  to  the  methods send, receive, and accept will block indefinitely,
              until the operation completes. The settimeout method defines a limit on the  amount
              of  time  the  I/O methods can block. When a timeout time has elapsed, the affected
              methods give up and fail with an error code.

              The amount of time to wait is specified as the value parameter, in seconds.

              The timeout modes are not implemented, the only settable timeout is the  inactivity
              time waiting for complete the internal buffer send or waiting for receive data.

              Arguments

                     · socket (class_socket) -- Is the manipulated Socket.

                     · value  (float)  --  The  timeout  value.  Use  floating  point  to specify
                       milliseconds.

       class Regex()
              This class allows the usage of HAProxy regexes because classic lua doesn't provides
              regexes. This class inherits the HAProxy compilation options, so the regexes can be
              libc regex, pcre regex or pcre JIT regex.

              The expression matching number is limited to  20  per  regex.  The  only  available
              option is case sensitive.

              Because  regexes  compilation  is  a heavy process, it is better to define all your
              regexes in the body context and use it during the runtime.

          -- Create the regex
          st, regex = Regex.new("needle (..) (...)", true);

          -- Check compilation errors
          if st == false then
            print "error: " .. regex
          end

          -- Match the regexes
          print(regex:exec("Looking for a needle in the haystack")) -- true
          print(regex:exec("Lokking for a cat in the haystack"))    -- false

          -- Extract words
          st, list = regex:match("Looking for a needle in the haystack")
          print(st)      -- true
          print(list[1]) -- needle in the
          print(list[2]) -- in
          print(list[3]) -- the

       Regex.new(regex, case_sensitive)
              Create and compile a regex.

              Arguments

                     · regex (string) -- The regular expression according with the libc  or  pcre
                       standard

                     · case_sensitive (boolean) -- Match is case sensitive or not.

              Returns
                     boolean status and Regex class or string containing fail reason.

       Regex.exec(regex, str)
              Execute the regex.

              Arguments

                     · regex (class_regex) -- A Regex class object.

                     · str (string) -- The input string will be compared with the compiled regex.

              Returns
                     a boolean status according with the match result.

       Regex.match(regex, str)
              Execute the regex and return matched expressions.

              Arguments

                     · map (class_map) -- A Regex class object.

                     · str (string) -- The input string will be compared with the compiled regex.

              Returns
                     a boolean status according with the match result, and a table containing all
                     the string matched in order of declaration.

       class Map()
              This class permits to do some lookup in HAProxy maps.  The  declared  maps  can  be
              modified during the runtime through the HAProxy management socket.

          default = "usa"

          -- Create and load map
          geo = Map.new("geo.map", Map._ip);

          -- Create new fetch that returns the user country
          core.register_fetches("country", function(txn)
            local src;
            local loc;

            src = txn.f:fhdr("x-forwarded-for");
            if (src == nil) then
              src = txn.f:src()
              if (src == nil) then
                return default;
              end
            end

            -- Perform lookup
            loc = geo:lookup(src);

            if (loc == nil) then
              return default;
            end

            return loc;
          end);

       Map._int
              See  the  HAProxy configuration.txt file, chapter "Using ACLs and fetching samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.int is also available for compatibility.

       Map._ip
              See the HAProxy configuration.txt file, chapter "Using ACLs and  fetching  samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.ip is also available for compatibility.

       Map._str
              See  the  HAProxy configuration.txt file, chapter "Using ACLs and fetching samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.str is also available for compatibility.

       Map._beg
              See the HAProxy configuration.txt file, chapter "Using ACLs and  fetching  samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.beg is also available for compatibility.

       Map._sub
              See  the  HAProxy configuration.txt file, chapter "Using ACLs and fetching samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.sub is also available for compatibility.

       Map._dir
              See the HAProxy configuration.txt file, chapter "Using ACLs and  fetching  samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.dir is also available for compatibility.

       Map._dom
              See  the  HAProxy configuration.txt file, chapter "Using ACLs and fetching samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.dom is also available for compatibility.

       Map._end
              See the HAProxy configuration.txt file, chapter "Using ACLs and  fetching  samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

       Map._reg
              See  the  HAProxy configuration.txt file, chapter "Using ACLs and fetching samples"
              ans subchapter "ACL basics" to understand this pattern matching method.

              Note that Map.reg is also available for compatibility.

       Map.new(file, method)
              Creates and load a map.

              Arguments

                     · file (string) -- Is the file containing the map.

                     · method (integer) -- Is the map pattern matching method. See the attributes
                       of the Map class.

              Returns
                     a class Map object.

              See    The   Map  attributes:  Map._int,  Map._ip,  Map._str,  Map._beg,  Map._sub,
                     Map._dir, Map._dom, Map._end and Map._reg.

       Map.lookup(map, str)
              Perform a lookup in a map.

              Arguments

                     · map (class_map) -- Is the class Map object.

                     · str (string) -- Is the string used as key.

              Returns
                     a string containing the result or nil if no match.

       Map.slookup(map, str)
              Perform a lookup in a map.

              Arguments

                     · map (class_map) -- Is the class Map object.

                     · str (string) -- Is the string used as key.

              Returns
                     a string containing the result or empty string if no match.

       class AppletHTTP()
              This class is used with applets that requires the 'http' mode. The http applet  can
              be  registered  with  the  core.register_service()  function.  They  are  used  for
              processing an http request like a server in back of HAProxy.

              This is an hello world sample code:

          core.register_service("hello-world", "http", function(applet)
             local response = "Hello World !"
             applet:set_status(200)
             applet:add_header("content-length", string.len(response))
             applet:add_header("content-type", "text/plain")
             applet:start_response()
             applet:send(response)
          end)

       AppletHTTP.c

              Returns
                     A Converters class

              This attribute contains a Converters class object.

       AppletHTTP.sc

              Returns
                     A Converters class

              This attribute contains a Converters class object. The  functions  of  this  object
              returns always a string.

       AppletHTTP.f

              Returns
                     A Fetches class

              This  attribute  contains  a  Fetches  class object. Note that the applet execution
              place cannot access to a valid  HAProxy  core  HTTP  transaction,  so  some  sample
              fetches related to the HTTP dependant values (hdr, path, ...) are not available.

       AppletHTTP.sf

              Returns
                     A Fetches class

              This  attribute  contains  a  Fetches  class  object.  The functions of this object
              returns always a string. Note that the applet execution place cannot  access  to  a
              valid  HAProxy  core  HTTP  transaction, so some sample fetches related to the HTTP
              dependant values (hdr, path, ...) are not available.

       AppletHTTP.method

              Returns
                     string

              The attribute method returns a string containing the HTTP method.

       AppletHTTP.version

              Returns
                     string

              The attribute version, returns a string containing the HTTP request version.

       AppletHTTP.path

              Returns
                     string

              The attribute path returns a string containing the HTTP request path.

       AppletHTTP.qs

              Returns
                     string

              The attribute qs returns a string containing the HTTP request query string.

       AppletHTTP.length

              Returns
                     integer

              The attribute length returns an integer containing the HTTP body length.

       AppletHTTP.headers

              Returns
                     table

              The attribute headers returns a table containing the HTTP headers. The header names
              are  always  in lower case. As the header name can be encountered more than once in
              each request, the value is indexed with 0 as first index value. The table have this
              form:

          AppletHTTP.headers['<header-name>'][<header-index>] = "<header-value>"

          AppletHTTP.headers["host"][0] = "www.test.com"
          AppletHTTP.headers["accept"][0] = "audio/basic q=1"
          AppletHTTP.headers["accept"][1] = "audio/*, q=0.2"
          AppletHTTP.headers["accept"][2] = "*/*, q=0.1"

       AppletHTTP.set_status(applet, code[, reason])
              This function sets the HTTP status code for the response. The allowed code are from
              100 to 599.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · code (integer) -- the status code returned to the client.

                     · reason (string) -- the status reason returned to the client (optional).

       AppletHTTP.add_header(applet, name, value)
              This function add an header in the response. Duplicated headers are not  collapsed.
              The special header content-length is used to determinate the response length. If it
              not exists, a transfer-encoding: chunked is set, and all the write from the funcion
              AppletHTTP:send() become a chunk.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · name (string) -- the header name

                     · value (string) -- the header value

       AppletHTTP.start_response(applet)
              This  function  indicates  to  the  HTTP  engine  that  it can process and send the
              response headers. After this called we cannot  add  headers  to  the  response;  We
              cannot use the AppletHTTP:send() function if the AppletHTTP:start_response() is not
              called.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

       AppletHTTP.getline(applet)
              This function returns a string containing one line from the http body. If the  data
              returned doesn't contains a final '\n' its assumed than its the last available data
              before the end of stream.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

              Returns
                     a string. The string can be empty if we reach the end of the stream.

       AppletHTTP.receive(applet[, size])
              Reads data from the HTTP body, according to the specified read size. If the size is
              missing, the function tries to read all the content of the stream until the end. If
              the size is bigger than the http body, it returns the amount of data available.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · size (integer) -- the required read size.

              Returns
                     always return a string,the string can be empty is the connexion is closed.

       AppletHTTP.send(applet, msg)
              Send the message msg on the http request body.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · msg (string) -- the message to send.

       AppletHTTP.get_priv(applet)
              Return Lua data stored in the current  transaction.  If  no  data  are  stored,  it
              returns a nil value.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

              Returns
                     the opaque data previously stored, or nil if nothing is available.

              See    AppletHTTP.set_priv()

       AppletHTTP.set_priv(applet, data)
              Store  any  data  in  the  current HAProxy transaction. This action replace the old
              stored data.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · data (opaque) -- The data which is stored in the transaction.

              See    AppletHTTP.get_priv()

       AppletHTTP.set_var(applet, var, value)
              Converts a Lua type in a HAProxy type and store it in a variable <var>.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

                     · value  (type)  --  The  value  associated  to the variable. The type ca be
                       string or integer.

              See    AppletHTTP.unset_var()

              See    AppletHTTP.get_var()

       AppletHTTP.unset_var(applet, var)
              Unset the variable <var>.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

              See    AppletHTTP.set_var()

              See    AppletHTTP.get_var()

       AppletHTTP.get_var(applet, var)
              Returns data stored in the variable <var> converter in Lua type.

              Arguments

                     · applet (class_AppletHTTP) -- An AppletHTTP class

                     · var  (string)  --  The  variable  name according with the HAProxy variable
                       syntax.

              See    AppletHTTP.set_var()

              See    AppletHTTP.unset_var()

       class AppletTCP()
              This class is used with applets that requires the 'tcp' mode. The tcp applet can be
              registered  with the core.register_service() function. They are used for processing
              a tcp stream like a server in back of HAProxy.

       AppletTCP.c

              Returns
                     A Converters class

              This attribute contains a Converters class object.

       AppletTCP.sc

              Returns
                     A Converters class

              This attribute contains a Converters class object. The  functions  of  this  object
              returns always a string.

       AppletTCP.f

              Returns
                     A Fetches class

              This attribute contains a Fetches class object.

       AppletTCP.sf

              Returns
                     A Fetches class

              This attribute contains a Fetches class object.

       AppletTCP.getline(applet)
              This  function  returns  a  string containing one line from the stream. If the data
              returned doesn't contains a final '\n' its assumed than its the last available data
              before the end of stream.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

              Returns
                     a string. The string can be empty if we reach the end of the stream.

       AppletTCP.receive(applet[, size])
              Reads  data  from the TCP stream, according to the specified read size. If the size
              is missing, the function tries to read all the content of the stream until the end.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · size (integer) -- the required read size.

              Returns
                     always return a string,the string can be empty is the connexion is closed.

       AppletTCP.send(appletmsg)
              Send the message on the stream.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · msg (string) -- the message to send.

       AppletTCP.get_priv(applet)
              Return Lua data stored in the current  transaction.  If  no  data  are  stored,  it
              returns a nil value.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

              Returns
                     the opaque data previously stored, or nil if nothing is available.

              See    AppletTCP.set_priv()

       AppletTCP.set_priv(applet, data)
              Store  any  data  in  the  current HAProxy transaction. This action replace the old
              stored data.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · data (opaque) -- The data which is stored in the transaction.

              See    AppletTCP.get_priv()

       AppletTCP.set_var(applet, var, value)
              Converts a Lua type in a HAProxy type and stores it in a variable <var>.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

                     · value  (type)  --  The  value  associated to the variable. The type can be
                       string or integer.

              See    AppletTCP.unset_var()

              See    AppletTCP.get_var()

       AppletTCP.unset_var(applet, var)
              Unsets the variable <var>.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · var (string) -- The variable name  according  with  the  HAProxy  variable
                       syntax.

              See    AppletTCP.unset_var()

              See    AppletTCP.set_var()

       AppletTCP.get_var(applet, var)
              Returns data stored in the variable <var> converter in Lua type.

              Arguments

                     · applet (class_AppletTCP) -- An AppletTCP class

                     · var  (string)  --  The  variable  name according with the HAProxy variable
                       syntax.

              See    AppletTCP.unset_var()

              See    AppletTCP.set_var()

       class StickTable()
              context: task, action, sample-fetch

              This class can be used to access the HAProxy stick tables from Lua.

       StickTable.info()
              Returns stick table attributes as  a  Lua  table.  See  HAProxy  documentation  for
              "stick-table" for canonical info, or check out example bellow.

              Returns
                     Lua table

              Assume our table has IPv4 key and gpc0 and conn_rate "columns":

          {
            expire=<int>,  # Value in ms
            size=<int>,    # Maximum table size
            used=<int>,    # Actual number of entries in table
            data={         # Data columns, with types as key, and periods as values
                             (-1 if type is not rate counter)
              conn_rate=<int>,
              gpc0=-1
            },
            length=<int>,  # max string length for string table keys, key length
                           # otherwise
            nopurge=<boolean>, # purge oldest entries when table is full
            type="ip"      # can be "ip", "ipv6", "integer", "string", "binary"
          }

       StickTable.lookup(key)
              Returns stick table entry for given <key>

              Arguments

                     · key (string) -- Stick table key (IP addresses and strings are supported)

              Returns
                     Lua table

       StickTable.dump([filter])
              Returns  all  entries  in  stick  table.  An optional filter can be used to extract
              entries with specific  data  values.  Filter  is  a  table  with  valid  comparison
              operators  as  keys  followed  by  data  type  name and value pairs.  Check out the
              HAProxy docs for "show table" for more details. For the  reference,  the  supported
              operators are:
                 "eq", "ne", "le", "lt", "ge", "gt"

              For  large  tables,  execution  of  this function can take a long time (for HAProxy
              standards). That's also true when filter is used, so  take  care  and  measure  the
              impact.

              Arguments

                     · filter (table) -- Stick table filter

              Returns
                     Stick table entries (table)

              See  below for example filter, which contains 4 entries (or comparisons).  (Maximum
              number of filter entries is 4, defined in the source code)

          local filter = {
            {"gpc0", "gt", 30}, {"gpc1", "gt", 20}}, {"conn_rate", "le", 10}
          }

       A lot of useful lua libraries can be found here:

       · https://lua-toolbox.com/

       Redis acces:

       · https://github.com/nrk/redis-lua

       This is an example about the usage of the Redis library with HAProxy. Note that each  call
       of any function of this library can throw an error if the socket connection fails.

          -- load the redis library
          local redis = require("redis");

          function do_something(txn)

             -- create and connect new tcp socket
             local tcp = core.tcp();
             tcp:settimeout(1);
             tcp:connect("127.0.0.1", 6379);

             -- use the redis library with this new socket
             local client = redis.connect({socket=tcp});
             client:ping();

          end

       OpenSSL:

       · http://mkottman.github.io/luacrypto/index.html

       · https://github.com/brunoos/luasec/wiki

AUTHOR

       Thierry FOURNIER

COPYRIGHT

       2019, Thierry FOURNIER