Provided by: haproxy_2.0.33-0ubuntu0.1_amd64 
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.
Warning: It is forbidden to alter the Channels buffer from HTTP contexts. So only
Channel.get_in_length(), Channel.get_out_length() and Channel.is_full() can be
called from an HTTP conetext.
[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
2023, Thierry FOURNIER