xenial (1) varnishd.1.gz

Provided by: varnish_4.1.1-1ubuntu0.2_amd64 bug

NAME

       varnishd - HTTP accelerator daemon

SYNOPSIS

       varnishd  [-a address[:port][,PROTO]] [-b host[:port]] [-C] [-d] [-F] [-f config] [-h type[,options]] [-i
       identity] [-j jail[,jailoptions]] [-l vsl[,vsm]] [-M address:port] [-n name] [-P file]  [-p  param=value]
       [-r  param[,param...]]  [-S secret-file] [-s [name=]kind[,options]] [-T address[:port]] [-t TTL] [-V] [-W
       waiter]

DESCRIPTION

       The varnishd daemon accepts HTTP requests from clients, passes them on to a backend server and caches the
       returned documents to better satisfy future requests for the same document.

OPTIONS

       -a <address[:port][,PROTO]>
              Listen  for  client  requests  on  the  specified address and port. The address can be a host name
              ("localhost"), an IPv4 dotted-quad ("127.0.0.1"), or an IPv6 address enclosed in  square  brackets
              ("[::1]").  If  address  is  not  specified,  varnishd  will listen on all available IPv4 and IPv6
              interfaces. If port is not specified, port 80 (http) is used.  An additional protocol type can  be
              set  for  the listening socket with PROTO.  Valid protocol types are: HTTP/1 (default), and PROXY.
              Multiple listening addresses can be specified by using multiple -a arguments.

       -b <host[:port]>
              Use the specified host as backend server. If port is not specified, the default is 8080.

       -C     Print VCL code compiled to C language and exit. Specify the  VCL  file  to  compile  with  the  -f
              option.

       -d     Enables  debugging  mode:  The  parent  process  runs  in  the foreground with a CLI connection on
              stdin/stdout, and the child process must be started explicitly with a CLI command. Terminating the
              parent process will also terminate the child.

       -F     Do not fork, run in the foreground.

       -f config
              Use  the  specified VCL configuration file instead of the builtin default.  See vcl(7) for details
              on VCL syntax.

              When neither a -f nor a -b argument are given, varnishd will not  start  the  worker  process  but
              process cli commands.

       -h <type[,options]>
              Specifies the hash algorithm. See Hash Algorithm Options for a list of supported algorithms.

       -i identity
              Specify the identity of the Varnish server. This can be accessed using server.identity from VCL.

       -j <jail[,jailoptions]>
              Specify the jailing technology to use.

       -l <vsl[,vsm]>
              Specifies size of shmlog file. vsl is the space for the VSL records [80M] and vsm is the space for
              stats counters [1M]. Scaling suffixes like 'K' and 'M' can be used up to (G)igabytes.  Default  is
              81 Megabytes.

       -M <address:port>
              Connect  to  this port and offer the command line interface.  Think of it as a reverse shell. When
              running with -M and there is no backend defined the child  process  (the  cache)  will  not  start
              initially.

       -n name
              Specify the name for this instance.  Amongst other things, this name is used to construct the name
              of the directory in which varnishd keeps temporary files and persistent state.  If  the  specified
              name  begins  with  a forward slash, it is interpreted as the absolute path to the directory which
              should be used for this purpose.

       -P file
              Write the PID of the process to the specified file.

       -p <param=value>
              Set the parameter specified by param to the specified value, see List of Parameters  for  details.
              This option can be used multiple times to specify multiple parameters.

       -r <param[,param...]>
              Make  the listed parameters read only. This gives the system administrator a way to limit what the
              Varnish CLI can do.   Consider  making  parameters  such  as  cc_command,  vcc_allow_inline_c  and
              vmod_dir read only as these can potentially be used to escalate privileges from the CLI.

       -S file
              Path  to  a  file  containing  a secret used for authorizing access to the management port. If not
              provided a new secret will be drawn from the system PRNG.

       -s <[name=]type[,options]>
              Use the specified storage backend, see Storage Backend Options.

              This option can be used multiple times to specify multiple storage files. Names are referenced  in
              logs, VCL, statistics, etc.

       -T <address[:port]>
              Offer  a  management  interface  on the specified address and port. See Management Interface for a
              list of management commands.

       -t TTL Specifies the default time to live (TTL) for cached objects. This is a shortcut for specifying the
              default_ttl run-time parameter.

       -V     Display the version number and exit.

       -W waiter
              Specifies the waiter type to use.

   Hash Algorithm Options
       The following hash algorithms are available:

       -h critbit
              self-scaling  tree  structure.  The  default  hash  algorithm in Varnish Cache 2.1 and onwards. In
              comparison to a more traditional B tree the critbit tree is almost  completely  lockless.  Do  not
              change this unless you are certain what you're doing.

       -h simple_list
              A simple doubly-linked list.  Not recommended for production use.

       -h <classic[,buckets]>
              A  standard  hash table. The hash key is the CRC32 of the object's URL modulo the size of the hash
              table.  Each table entry points to a list of elements which share the same hash key.  The  buckets
              parameter specifies the number of entries in the hash table.  The default is 16383.

   Storage Backend Options
       The following storage types are available:

       -s <malloc[,size]>
              malloc is a memory based backend.

       -s <file,path[,size[,granularity]]>
              The file backend stores data in a file on disk. The file will be accessed using mmap.

              The  path  is  mandatory.  If path points to a directory, a temporary file will be created in that
              directory and immediately unlinked. If path points to  a  non-existing  file,  the  file  will  be
              created.

              If size is omitted, and path points to an existing file with a size greater than zero, the size of
              that file will be used. If not, an error is reported.

              Granularity sets the allocation block size. Defaults to the system page  size  or  the  filesystem
              block size, whichever is larger.

       -s <persistent,path,size>
              Persistent storage. Varnish will store objects in a file in a manner that will secure the survival
              of most of the objects in the event of a planned or unplanned shutdown of Varnish. The  persistent
              storage  backend  has  multiple issues with it and will likely be removed from a future version of
              Varnish.

   Jail Options
       Varnish jails are a generalization over various platform specific methods to  reduce  the  privileges  of
       varnish processes. They may have specific options. Available jails are:

       -j solaris
              Reduce privileges(5) for varnishd and sub-process to the minimally required set. Only available on
              platforms which have the setppriv(2) call.

       -j <unix[,user=`user`][,ccgroup=`group`]>
              Default on all other platforms if varnishd is either started with  an  effective  uid  of  0  ("as
              root") or as user varnish.

              With  the  unix  jail  technology  activated,  varnish  will  switch  to  an  alternative user for
              subprocesses and change the effective uid of the master process whenever possible.

              The optional user argument specifies which alternative user to use. It defaults to varnish

              The optional ccgroup argument specifies a group to add to varnish subprocesses requiring access to
              a c-compiler. There is no default.

       -j none
              last  resort  jail  choice:  With  jail  technology  none, varnish will run all processes with the
              privileges it was started with.

   Management Interface
       If the -T option was specified, varnishd will offer a command-line management interface on the  specified
       address  and port.  The recommended way of connecting to the command-line management interface is through
       varnishadm(1).

       The commands available are documented in varnish(7).

RUN TIME PARAMETERS

   Run Time Parameter Flags
       Runtime parameters are marked with shorthand flags to avoid repeating the same text over and over in  the
       table below. The meaning of the flags are:

       • experimental

         We have no solid information about good/bad/optimal values for this parameter. Feedback with experience
         and observations are most welcome.

       • delayed

         This parameter can be changed on the fly, but will not take effect immediately.

       • restart

         The worker process must be stopped and restarted, before this parameter takes effect.

       • reload

         The VCL programs must be reloaded for this parameter to take effect.

       • experimental

         We're not really sure about this parameter, tell us what you find.

       • wizard

         Do not touch unless you really know what you're doing.

       • only_root

         Only works if varnishd is running as root.

   Default Value Exceptions on 32 bit Systems
       Be aware that on 32 bit systems, certain default values are reduced relative to the values listed  below,
       in order to conserve VM space:

       • workspace_client: 16k

       • thread_pool_workspace: 16k

       • http_resp_size: 8k

       • http_req_size: 12k

       • gzip_stack_buffer: 4k

       • thread_pool_stack: 64k

   List of Parameters
       This text is produced from the same text you will find in the CLI if you use the param.show command:

   accept_filter
          • Units: bool

          • Default: off

          • Flags: must_restart

       Enable kernel accept-filters (if available in the kernel).

   acceptor_sleep_decay
          • Default: 0.9

          • Minimum: 0

          • Maximum: 1

          • Flags: experimental

       If  we  run out of resources, such as file descriptors or worker threads, the acceptor will sleep between
       accepts.  This parameter (multiplicatively) reduce the sleep duration for each  successful  accept.  (ie:
       0.9 = reduce by 10%)

   acceptor_sleep_incr
          • Units: seconds

          • Default: 0.000

          • Minimum: 0.000

          • Maximum: 1.000

          • Flags: experimental

       If  we  run out of resources, such as file descriptors or worker threads, the acceptor will sleep between
       accepts.  This parameter control how much longer we sleep, each time we fail to accept a new connection.

   acceptor_sleep_max
          • Units: seconds

          • Default: 0.050

          • Minimum: 0.000

          • Maximum: 10.000

          • Flags: experimental

       If we run out of resources, such as file descriptors or worker threads, the acceptor will  sleep  between
       accepts.  This parameter limits how long it can sleep between attempts to accept new connections.

   auto_restart
          • Units: bool

          • Default: on

       Automatically restart the child/worker process if it dies.

   backend_idle_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 1.000

       Timeout before we close unused backend connections.

   ban_dups
          • Units: bool

          • Default: on

       Eliminate  older  identical bans when a new ban is added.  This saves CPU cycles by not comparing objects
       to identical bans.  This is a waste of time if you have many bans which are never identical.

   ban_lurker_age
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

       The ban lurker will ignore bans until they are this old.  When a ban is added, the active traffic will be
       tested  against  it as part of object lookup.  This parameter holds the ban-lurker off, until the rush is
       over.

   ban_lurker_batch
          • Default: 1000

          • Minimum: 1

       The ban lurker sleeps ${ban_lurker_sleep} after examining this  many  objects.   Use  this  to  pace  the
       ban-lurker if it eats too many resources.

   ban_lurker_sleep
          • Units: seconds

          • Default: 0.010

          • Minimum: 0.000

       How  long  the  ban  lurker  sleeps  after  examining  ${ban_lurker_batch} objects.  Use this to pace the
       ban-lurker if it eats too many resources.  A value of zero will disable the ban lurker entirely.

   between_bytes_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

       We only wait for this many seconds between bytes received from the backend before giving up the fetch.  A
       value of zero means never give up.  VCL values, per backend or per backend request take precedence.  This
       parameter does not apply to pipe'ed requests.

   cc_command
          • Default: "exec gcc -std=gnu99 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wall
            -Werror -Wno-error=unused-result -pthread -fpic -shared -Wl,-x -o %o %s"

          • Flags: must_reload

       Command used for compiling the C source code to a dlopen(3) loadable object.  Any occurrence of %s in the
       string will be replaced with the source file name, and %o will be replaced with the output file name.

   cli_buffer
          • Units: bytes

          • Default: 8k

          • Minimum: 4k

       Size of buffer for CLI command input.  You may need to increase this if you have big VCL  files  and  use
       the vcl.inline CLI command.  NB: Must be specified with -p to have effect.

   cli_limit
          • Units: bytes

          • Default: 48k

          • Minimum: 128b

          • Maximum: 99999999b

       Maximum  size of CLI response.  If the response exceeds this limit, the response code will be 201 instead
       of 200 and the last line will indicate the truncation.

   cli_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

       Timeout for the childs replies to CLI requests from the mgt_param.

   clock_skew
          • Units: seconds

          • Default: 10

          • Minimum: 0

       How much clockskew we are willing to accept between the backend and our own clock.

   connect_timeout
          • Units: seconds

          • Default: 3.500

          • Minimum: 0.000

       Default connection timeout for backend connections. We only try to connect to the backend for  this  many
       seconds before giving up. VCL can override this default value for each backend and backend request.

   critbit_cooloff
          • Units: seconds

          • Default: 180.000

          • Minimum: 60.000

          • Maximum: 254.000

          • Flags: wizard

       How long the critbit hasher keeps deleted objheads on the cooloff list.

   debug
          • Default: none

       Enable/Disable various kinds of debugging.

          none   Disable all debugging

       Use +/- prefix to set/reset individual bits:

          req_state
                 VSL Request state engine

          workspace
                 VSL Workspace operations

          waiter VSL Waiter internals

          waitinglist
                 VSL Waitinglist events

          syncvsl
                 Make VSL synchronous

          hashedge
                 Edge cases in Hash

          vclrel Rapid VCL release

          lurker VSL Ban lurker

          esi_chop
                 Chop ESI fetch to bits

          flush_head
                 Flush after http1 head

          vtc_mode
                 Varnishtest Mode

          witness
                 Emit WITNESS lock records

          vsm_keep
                 Keep the VSM file on restart

   default_grace
          • Units: seconds

          • Default: 10.000

          • Minimum: 0.000

          • Flags: obj_sticky

       Default  grace period.  We will deliver an object this long after it has expired, provided another thread
       is attempting to get a new copy.

   default_keep
          • Units: seconds

          • Default: 0.000

          • Minimum: 0.000

          • Flags: obj_sticky

       Default keep period.  We will keep a useless object around this long, making it available for conditional
       backend fetches.  That means that the object will be removed from the cache at the end of ttl+grace+keep.

   default_ttl
          • Units: seconds

          • Default: 120.000

          • Minimum: 0.000

          • Flags: obj_sticky

       The TTL assigned to objects if neither the backend nor the VCL code assigns one.

   feature
          • Default: none

       Enable/Disable various minor features.

          none   Disable all features.

       Use +/- prefix to enable/disable individual feature:

          short_panic
                 Short panic message.

          wait_silo
                 Wait for persistent silo.

          no_coredump
                 No coredumps.

          esi_ignore_https
                 Treat HTTPS as HTTP in ESI:includes

          esi_disable_xml_check
                 Don't check of body looks like XML

          esi_ignore_other_elements
                 Ignore non-esi XML-elements

          esi_remove_bom
                 Remove UTF-8 BOM

   fetch_chunksize
          • Units: bytes

          • Default: 16k

          • Minimum: 4k

          • Flags: experimental

       The  default  chunksize  used  by  fetcher. This should be bigger than the majority of objects with short
       TTLs.  Internal limits in the storage_file module makes increases above 128kb a dubious idea.

   fetch_maxchunksize
          • Units: bytes

          • Default: 0.25G

          • Minimum: 64k

          • Flags: experimental

       The maximum chunksize we attempt to allocate from storage. Making this too large  may  cause  delays  and
       storage fragmentation.

   first_byte_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

       Default  timeout  for receiving first byte from backend. We only wait for this many seconds for the first
       byte before giving up. A value of 0 means it will never time out. VCL can override this default value for
       each backend and backend request. This parameter does not apply to pipe.

   gzip_buffer
          • Units: bytes

          • Default: 32k

          • Minimum: 2k

          • Flags: experimental

       Size of malloc buffer used for gzip processing.  These buffers are used for in-transit data, for instance
       gunzip'ed data being sent to a client.Making this space to small results  in  more  overhead,  writes  to
       sockets etc, making it too big is probably just a waste of memory.

   gzip_level
          • Default: 6

          • Minimum: 0

          • Maximum: 9

       Gzip compression level: 0=debug, 1=fast, 9=best

   gzip_memlevel
          • Default: 8

          • Minimum: 1

          • Maximum: 9

       Gzip memory level 1=slow/least, 9=fast/most compression.  Memory impact is 1=1k, 2=2k, ... 9=256k.

   http_gzip_support
          • Units: bool

          • Default: on

       Enable  gzip  support.  When  enabled  Varnish request compressed objects from the backend and store them
       compressed. If a client does not support gzip encoding Varnish  will  uncompress  compressed  objects  on
       demand. Varnish will also rewrite the Accept-Encoding header of clients indicating support for gzip to:
              Accept-Encoding: gzip

       Clients  that do not support gzip will have their Accept-Encoding header removed. For more information on
       how gzip is implemented please see the chapter on gzip in the Varnish reference.

   http_max_hdr
          • Units: header lines

          • Default: 64

          • Minimum: 32

          • Maximum: 65535

       Maximum number of HTTP header lines we allow in {req|resp|bereq|beresp}.http (obj.http  is  autosized  to
       the  exact number of headers).  Cheap, ~20 bytes, in terms of workspace memory.  Note that the first line
       occupies five header lines.

   http_range_support
          • Units: bool

          • Default: on

       Enable support for HTTP Range headers.

   http_req_hdr_len
          • Units: bytes

          • Default: 8k

          • Minimum: 40b

       Maximum length of any HTTP client request header we will allow.  The limit is inclusive its  continuation
       lines.

   http_req_size
          • Units: bytes

          • Default: 32k

          • Minimum: 0.25k

       Maximum number of bytes of HTTP client request we will deal with.  This is a limit on all bytes up to the
       double blank line which ends the HTTP request.  The memory for the request is allocated from  the  client
       workspace  (param: workspace_client) and this parameter limits how much of that the request is allowed to
       take up.

   http_resp_hdr_len
          • Units: bytes

          • Default: 8k

          • Minimum: 40b

       Maximum length of any  HTTP  backend  response  header  we  will  allow.   The  limit  is  inclusive  its
       continuation lines.

   http_resp_size
          • Units: bytes

          • Default: 32k

          • Minimum: 0.25k

       Maximum  number  of bytes of HTTP backend response we will deal with.  This is a limit on all bytes up to
       the double blank line which ends the HTTP request.  The memory for the  request  is  allocated  from  the
       backend  workspace  (param:  workspace_backend) and this parameter limits how much of that the request is
       allowed to take up.

   idle_send_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

          • Flags: delayed

       Time to wait with no data sent. If no data has been transmitted in  this  many  seconds  the  session  is
       closed.  See setsockopt(2) under SO_SNDTIMEO for more information.

   listen_depth
          • Units: connections

          • Default: 1024

          • Minimum: 0

          • Flags: must_restart

       Listen queue depth.

   lru_interval
          • Units: seconds

          • Default: 2.000

          • Minimum: 0.000

          • Flags: experimental

       Grace  period  before  object  moves on LRU list.  Objects are only moved to the front of the LRU list if
       they have not been moved there already inside this timeout period.   This  reduces  the  amount  of  lock
       operations necessary for LRU list access.

   max_esi_depth
          • Units: levels

          • Default: 5

          • Minimum: 0

       Maximum depth of esi:include processing.

   max_restarts
          • Units: restarts

          • Default: 4

          • Minimum: 0

       Upper  limit  on  how many times a request can restart.  Be aware that restarts are likely to cause a hit
       against the backend, so don't increase thoughtlessly.

   max_retries
          • Units: retries

          • Default: 4

          • Minimum: 0

       Upper limit on how many times a backend fetch can retry.

   nuke_limit
          • Units: allocations

          • Default: 50

          • Minimum: 0

          • Flags: experimental

       Maximum number of objects we attempt to nuke in order to make space for a object body.

   pcre_match_limit
          • Default: 10000

          • Minimum: 1

       The limit for the number of calls to the internal match() function in pcre_exec().

       (See: PCRE_EXTRA_MATCH_LIMIT in pcre docs.)

       This parameter limits how much CPU time regular expression matching can soak up.

   pcre_match_limit_recursion
          • Default: 20

          • Minimum: 1

       The recursion depth-limit for the internal match() function in a pcre_exec().

       (See: PCRE_EXTRA_MATCH_LIMIT_RECURSION in pcre docs.)

       This puts an upper limit on the amount of stack used by PCRE for certain classes of regular expressions.

       We have set the default value low in order to prevent crashes, at the cost of  possible  regexp  matching
       failures.

       Matching failures will show up in the log as VCL_Error messages with regexp errors -27 or -21.

       Testcase r01576 can be useful when tuning this parameter.

   ping_interval
          • Units: seconds

          • Default: 3

          • Minimum: 0

          • Flags: must_restart

       Interval between pings from parent to child.  Zero will disable pinging entirely, which makes it possible
       to attach a debugger to the child.

   pipe_timeout
          • Units: seconds

          • Default: 60.000

          • Minimum: 0.000

       Idle timeout for PIPE sessions. If nothing have been received in either direction for this many  seconds,
       the session is closed.

   pool_req
          • Default: 10,100,10

       Parameters for per worker pool request memory pool.  The three numbers are:

          min_pool
                 minimum size of free pool.

          max_pool
                 maximum size of free pool.

          max_age
                 max age of free element.

   pool_sess
          • Default: 10,100,10

       Parameters for per worker pool session memory pool.  The three numbers are:

          min_pool
                 minimum size of free pool.

          max_pool
                 maximum size of free pool.

          max_age
                 max age of free element.

   pool_vbo
          • Default: 10,100,10

       Parameters for backend object fetch memory pool.  The three numbers are:

          min_pool
                 minimum size of free pool.

          max_pool
                 maximum size of free pool.

          max_age
                 max age of free element.

   prefer_ipv6
          • Units: bool

          • Default: off

       Prefer IPv6 address when connecting to backends which have both IPv4 and IPv6 addresses.

   rush_exponent
          • Units: requests per request

          • Default: 3

          • Minimum: 2

          • Flags: experimental

       How  many  parked  request  we start for each completed request on the object.  NB: Even with the implict
       delay of delivery, this parameter controls an exponential increase in number of worker threads.

   send_timeout
          • Units: seconds

          • Default: 600.000

          • Minimum: 0.000

          • Flags: delayed

       Send timeout for client connections. If the HTTP response hasn't been transmitted in  this  many  seconds
       the session is closed.  See setsockopt(2) under SO_SNDTIMEO for more information.

   session_max
          • Units: sessions

          • Default: 100000

          • Minimum: 1000

       Maximum  number  of  sessions  we  will allocate from one pool before just dropping connections.  This is
       mostly an anti-DoS measure, and setting it plenty high should not hurt, as long as you  have  the  memory
       for it.

   shm_reclen
          • Units: bytes

          • Default: 255b

          • Minimum: 16b

          • Maximum: 4084

       Old name for vsl_reclen, use that instead.

   shortlived
          • Units: seconds

          • Default: 10.000

          • Minimum: 0.000

       Objects created with (ttl+grace+keep) shorter than this are always put in transient storage.

   sigsegv_handler
          • Units: bool

          • Default: on

          • Flags: must_restart

       Install  a  signal  handler  which tries to dump debug information on segmentation faults, bus errors and
       abort signals.

   syslog_cli_traffic
          • Units: bool

          • Default: on

       Log all CLI traffic to syslog(LOG_INFO).

   tcp_keepalive_intvl
          • Units: seconds

          • Default: 75.000

          • Minimum: 1.000

          • Maximum: 100.000

          • Flags: experimental

       The number of seconds between TCP keep-alive probes.

   tcp_keepalive_probes
          • Units: probes

          • Default: 9

          • Minimum: 1

          • Maximum: 100

          • Flags: experimental

       The maximum number of TCP keep-alive probes to send before giving up and killing  the  connection  if  no
       response is obtained from the other end.

   tcp_keepalive_time
          • Units: seconds

          • Default: 7200.000

          • Minimum: 1.000

          • Maximum: 7200.000

          • Flags: experimental

       The number of seconds a connection needs to be idle before TCP begins sending out keep-alive probes.

   thread_pool_add_delay
          • Units: seconds

          • Default: 0.000

          • Minimum: 0.000

          • Flags: experimental

       Wait at least this long after creating a thread.

       Some  (buggy)  systems  may  need a short (sub-second) delay between creating threads.  Set this to a few
       milliseconds if you see the 'threads_failed' counter grow too much.

       Setting this too high results in insuffient worker threads.

   thread_pool_destroy_delay
          • Units: seconds

          • Default: 1.000

          • Minimum: 0.010

          • Flags: delayed, experimental

       Wait this long after destroying a thread.

       This controls the decay of thread pools when idle(-ish).

   thread_pool_fail_delay
          • Units: seconds

          • Default: 0.200

          • Minimum: 0.010

          • Flags: experimental

       Wait at least this long after a failed thread creation before trying to create another thread.

       Failure to create a worker thread is often a sign that  the end is near, because the process  is  running
       out of some resource.  This delay tries to not rush the end on needlessly.

       If thread creation failures are a problem, check that thread_pool_max is not too high.

       It  may also help to increase thread_pool_timeout and thread_pool_min, to reduce the rate at which treads
       are destroyed and later recreated.

   thread_pool_max
          • Units: threads

          • Default: 5000

          • Minimum: 100

          • Flags: delayed

       The maximum number of worker threads in each pool.

       Do not set this higher than you have to, since excess worker threads soak up RAM and  CPU  and  generally
       just get in the way of getting work done.

   thread_pool_min
          • Units: threads

          • Default: 100

          • Maximum: 5000

          • Flags: delayed

       The minimum number of worker threads in each pool.

       Increasing this may help ramp up faster from low load situations or when threads have expired.

       Minimum is 10 threads.

   thread_pool_stack
          • Units: bytes

          • Default: 48k

          • Minimum: 16k

          • Flags: experimental

       Worker  thread stack size.  This will likely be rounded up to a multiple of 4k (or whatever the page_size
       might be) by the kernel.

   thread_pool_timeout
          • Units: seconds

          • Default: 300.000

          • Minimum: 10.000

          • Flags: delayed, experimental

       Thread idle threshold.

       Threads in excess of thread_pool_min, which have been idle for at least this long, will be destroyed.

   thread_pools
          • Units: pools

          • Default: 2

          • Minimum: 1

          • Flags: delayed, experimental

       Number of worker thread pools.

       Increasing number of worker pools decreases lock contention.

       Too many pools waste CPU and RAM resources, and more than one pool for each CPU is probably  detrimal  to
       performance.

       Can be increased on the fly, but decreases require a restart to take effect.

   thread_queue_limit
          • Default: 20

          • Minimum: 0

          • Flags: experimental

       Permitted queue length per thread-pool.

       This  sets  the  number  of  requests  we  will queue, waiting for an available thread.  Above this limit
       sessions will be dropped instead of queued.

   thread_stats_rate
          • Units: requests

          • Default: 10

          • Minimum: 0

          • Flags: experimental

       Worker threads accumulate statistics, and dump these into the global stats counters if the lock  is  free
       when  they finish a job (request/fetch etc.)  This parameters defines the maximum number of jobs a worker
       thread may handle, before it is forced to dump its accumulated stats into the global counters.

   timeout_idle
          • Units: seconds

          • Default: 5.000

          • Minimum: 0.000

       Idle timeout for client connections.  A connection is considered idle, until we have  received  the  full
       request headers.

   timeout_linger
          • Units: seconds

          • Default: 0.050

          • Minimum: 0.000

          • Flags: experimental

       How  long  the  worker  thread  lingers  on  an  idle session before handing it over to the waiter.  When
       sessions are reused, as much as half of all reuses happen within the  first  100  msec  of  the  previous
       request  completing.   Setting this too high results in worker threads not doing anything for their keep,
       setting it too low just means that more sessions take a detour around the waiter.

   vcc_allow_inline_c
          • Units: bool

          • Default: off

       Allow inline C code in VCL.

   vcc_err_unref
          • Units: bool

          • Default: on

       Unreferenced VCL objects result in error.

   vcc_unsafe_path
          • Units: bool

          • Default: on

       Allow '/' in vmod & include paths.  Allow 'import ... from ...'.

   vcl_cooldown
          • Units: seconds

          • Default: 600.000

          • Minimum: 0.000

       How long a VCL is kept warm after  being  replaced  as  the  active  VCL  (granularity  approximately  30
       seconds).

   vcl_dir
          • Default: /etc/varnish

       Directory  (or  colon  separated  list  of  directories)  from which relative VCL filenames (vcl.load and
       include) are to be found.

   vmod_dir
          • Default: /usr/lib/x86_64-linux-gnu/varnish/vmods

       Directory (or colon separated list of directories) where VMODs are to be found.

   vsl_buffer
          • Units: bytes

          • Default: 4k

          • Minimum: 267

       Bytes of (req-/backend-)workspace dedicated to buffering  VSL  records.   Setting  this  too  high  costs
       memory,  setting  it  too  low will cause more VSL flushes and likely increase lock-contention on the VSL
       mutex.

       The minimum tracks the vsl_reclen parameter + 12 bytes.

   vsl_mask
          • Default: -VCL_trace,-WorkThread,-Hash,-VfpAcct

       Mask individual VSL messages from being logged.

          default
                 Set default value

       Use +/- prefix in front of VSL tag name, to mask/unmask individual VSL messages.

   vsl_reclen
          • Units: bytes

          • Default: 255b

          • Minimum: 16b

          • Maximum: 4084b

       Maximum number of bytes in SHM log record.

       The maximum tracks the vsl_buffer parameter - 12 bytes.

   vsl_space
          • Units: bytes

          • Default: 80M

          • Minimum: 1M

          • Flags: must_restart

       The amount of space to allocate for the VSL fifo buffer in the VSM memory segment.  If you make this  too
       small,  varnish{ncsa|log}  etc  will  not  be  able  to  keep  up.  Making it too large just costs memory
       resources.

   vsm_space
          • Units: bytes

          • Default: 1M

          • Minimum: 1M

          • Flags: must_restart

       The amount of space to allocate for stats counters in the VSM memory  segment.   If  you  make  this  too
       small, some counters will be invisible.  Making it too large just costs memory resources.

   workspace_backend
          • Units: bytes

          • Default: 64k

          • Minimum: 1k

          • Flags: delayed

       Bytes  of HTTP protocol workspace for backend HTTP req/resp.  If larger than 4k, use a multiple of 4k for
       VM efficiency.

   workspace_client
          • Units: bytes

          • Default: 64k

          • Minimum: 9k

          • Flags: delayed

       Bytes of HTTP protocol workspace for clients HTTP req/resp.  If larger than 4k, use a multiple of 4k  for
       VM efficiency.

   workspace_session
          • Units: bytes

          • Default: 0.50k

          • Minimum: 0.25k

          • Flags: delayed

       Allocation  size  for  session  structure  and  workspace.     The  workspace  is  primarily used for TCP
       connection addresses.  If larger than 4k, use a multiple of 4k for VM efficiency.

   workspace_thread
          • Units: bytes

          • Default: 2k

          • Minimum: 0.25k

          • Maximum: 8k

          • Flags: delayed

       Bytes of auxiliary workspace per thread.  This workspace is used for certain  temporary  data  structures
       during  the  operation  of  a  worker  thread.   One  use  is for the io-vectors for writing requests and
       responses to sockets, having too little space will result in more writev(2) system calls, having too much
       just wastes the space.

EXIT CODES

       Varnish and bundled tools will, in most cases, exit with one of the following codes

       • 0 OK

       • 1 Some error which could be system-dependent and/or transient

       • 2  Serious  configuration / parameter error - retrying with the same configuration / parameters is most
         likely useless

       The varnishd master process may also OR its exit code

       • with 0x20 when the varnishd child process died,

       • with 0x40 when the varnishd child process was terminated by a signal and

       • with 0x80 when a core was dumped.

SEE ALSO

varnishlog(1)varnishhist(1)varnishncsa(1)varnishstat(1)varnishtop(1)varnish-cli(7)vcl(7)

HISTORY

       The varnishd daemon was developed by Poul-Henning Kamp in cooperation with Verdens Gang  AS  and  Varnish
       Software.

       This  manual  page  was  written  by  Dag-Erling  Smørgrav  with  updates  by  Stig  Sandbeck Mathisen <‐
       ssm@debian.org>, Nils Goroll and others.

       This document is licensed under the same licence as Varnish itself. See LICENCE for details.

       • Copyright (c) 2007-2015 Varnish Software AS

                                                                                                     VARNISHD(1)