Provided by: varnish_6.1.1-1_amd64 bug

NAME

       varnishd - HTTP accelerator daemon

SYNOPSIS

       varnishd  [-a [name=][address][:port][,PROTO][,user=<user>][,group=<group>][,mode=<mode>]]
       [-b [host[:port]|path]] [-C] [-d] [-F] [-f config] [-h type[,options]]  [-I  clifile]  [-i
       identity]  [-j  jail[,jailoptions]]  [-l  vsl]  [-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]

       varnishd [-x parameter|vsl|cli|builtin|optstring]

       varnishd [-?]

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

   Basic options
       -a <[name=][address][:port][,PROTO][,user=<user>][,group=<group>][,mode=<mode>]>
          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"), an IPv6 address enclosed in
          square brackets ("[::1]"), or a path beginning with a '/'  for  a  Unix  domain  socket
          ("/path/to/listen.sock").  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.
          At least one of address or port is required.

          If  a  Unix  domain socket is specified as the listen address, then the user, group and
          mode sub-arguments may be used to specify the permissions of the  socket  file  --  use
          names  for  user and group, and a 3-digit octal value for mode. These sub-arguments are
          not permitted if an IP address is specified. When Unix domain socket listeners  are  in
          use, all VCL configurations must have version >= 4.1.

          Name  is  referenced  in  logs.  If name is not specified, "a0", "a1", etc. 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 different -a arguments.

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

              If the value of -b begins with /, it is interpreted as the absolute path of a  Unix
              domain socket to which Varnish connects. In that case, the value of -b must satisfy
              the conditions required for the .path field of a backend declaration,  see  vcl(7).
              Backends with Unix socket addresses may only be used with VCL versions >= 4.1.

              -b can be used only once, and not together with f.

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

              If a single -f option is used, then the VCL instance loaded from the file is  named
              "boot"  and immediately becomes active. If more than one -f option is used, the VCL
              instances are named "boot0", "boot1" and so forth, in the  order  corresponding  to
              the -f arguments, and the last one is named "boot", which becomes active.

              Either  -b  or  one  or  more  -f options must be specified, but not both, and they
              cannot both be left out, unless -d is used to start varnishd in debugging mode.  If
              the  empty  string is specified as the sole -f option, then varnishd starts without
              starting the worker process, and the management process will accept  CLI  commands.
              You  can  also combine an empty -f option with an initialization script (-I option)
              and the child process will be started if there is an active VCL at the end  of  the
              initialization.

              When  used  with  a  relative  file name, config is searched in the vcl_path. It is
              possible to set this path prior to using  -f  options  with  a  -p  option.  During
              startup,   varnishd   doesn't   complain   about   unsafe  VCL  paths:  unlike  the
              varnish-cli(7) that could later be accessed remotely,  starting  varnishd  requires
              local privileges.

       -n name
              Specify the name for this instance.  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.

   Documentation options
       For these options, varnishd prints information to standard output and  exits.  When  a  -x
       option  is used, it must be the only option (it outputs documentation in reStructuredText,
       aka RST).

       -?
          Print the usage message.

       -x parameter
              Print documentation of the runtime parameters (-p options), see List of Parameters.

       -x vsl Print documentation of the tags used in the Varnish shared memory log, see vsl(7).

       -x cli Print documentation of the command line interface, see varnish-cli(7).

       -x builtin
              Print the contents of the default VCL program builtin.vcl.

       -x optstring
              Print the optstring parameter to getopt(3) to help writing wrapper scripts.

   Operations options
       -F     Do not fork, run in the foreground. Only one of -F or -d can be specified,  and  -F
              cannot be used together with -C.

       -T <address[:port]>
              Offer  a management interface on the specified address and port. See varnish-cli(7)
              for documentation of the management commands.  To disable the management  interface
              use none.

       -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.

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

       -i identity
              Specify   the   identity  of  the  Varnish  server.  This  can  be  accessed  using
              server.identity from VCL and with VSM_Name() from utilities.  If not specified  the
              output of gethostname(3) is used.

       -I clifile
              Execute  the management commands in the file given as clifile before the the worker
              process starts, see CLI Command File.

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

       -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.

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

              This option can be used multiple times to specify multiple storage files.  Name  is
              referenced  in logs, VCL, statistics, etc. If name is not specified, "s0", "s1" and
              so forth is used.

       -l <vsl>
              Specifies size of the space for the VSL records.  Scaling suffixes like 'K' and 'M'
              can be used up to (G)igabytes.  Default is 80 Megabytes.

   Security options
       -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_path  read  only  as these can potentially be used to
              escalate privileges from the CLI.

       -S secret-file
              Path to a file containing a secret used for authorizing access  to  the  management
              port. To disable authentication use none.

              If  this  argument  is  not  provided,  a secret drawn from the system PRNG will be
              written to a file called _.secret in the working directory (see opt_n) with default
              ownership and permissions of the user having started varnish.

              Thus, users wishing to delegate control over varnish will probably want to create a
              custom secret file with appropriate permissions (ie. readable by a  unix  group  to
              delegate control to).

       -j <jail[,jailoptions]>
              Specify the jailing mechanism to use. See Jail section.

   Advanced, development and debugging options
       -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.

              Only one of -d or -F can be specified, and -d cannot be used together with -C.

       -C     Print  VCL  code  compiled  to C language and exit. Specify the VCL file to compile
              with the -f option. Either -f or -b must be used with -C, and  -C  cannot  be  used
              with -F or -d.

       -V     Display the version number and exit. This must be the only option.

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

       -W waiter
              Specifies the waiter type to use.

   Hash Algorithm
       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
       The following storage types are available:

       -s <default[,size]>
              The default storage type resolves to umem where available and malloc otherwise.

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

       -s <umem[,size]>
              umem is a storage backend which is more efficient than malloc on platforms where it
              is available.

              See the section on umem in chapter Storage backends of The Varnish Users Guide  for
              details.

       -s <file,path[,size[,granularity[,advice]]]>
              The  file  backend  stores  data in a file on disk. The file will be accessed using
              mmap. Note that this storage provide no cache persistence.

              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.

              Advice tells the kernel how varnishd expects to use this mapped region so that  the
              kernel  can  choose  the  appropriate  read-ahead  and caching techniques. Possible
              values are normal, random and sequential, corresponding to MADV_NORMAL, MADV_RANDOM
              and MADV_SEQUENTIAL madvise() advice argument, respectively. Defaults to random.

       -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.

       You can also prefix the type with NAME= to explicitly name a storage:

          -s myStorage=malloc,5G

       This allows to address it more easily in VCL:

          set beresp.storage = storage.myStorage;

       If the name is omitted, Varnish will name storages sN, starting with s0 and incrementing N
       for every new storage.

   Jail
       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`][,workuser=`user`]>
              Default  on all other platforms when varnishd is started with an effective uid of 0
              ("as root").

              With the unix jail mechanism 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.

              The optional workuser argument specifies an alternative user to use for the  worker
              process. It defaults to vcache.

       -j none
              last  resort  jail choice: With jail mechanism 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-cli(7).

   CLI Command File
       The -I option makes it possible to run arbitrary  management  commands  when  varnishd  is
       launched,  before  the  worker  process is started. In particular, this is the way to load
       configurations, apply labels to them, and make a  VCL  instance  active  that  uses  those
       labels on startup:

          vcl.load panic /etc/varnish_panic.vcl
          vcl.load siteA0 /etc/varnish_siteA.vcl
          vcl.load siteB0 /etc/varnish_siteB.vcl
          vcl.load siteC0 /etc/varnish_siteC.vcl
          vcl.label siteA siteA0
          vcl.label siteB siteB0
          vcl.label siteC siteC0
          vcl.load main /etc/varnish_main.vcl
          vcl.use main

       Every  line  in  the  file,  including  the  last line, must be terminated by a newline or
       carriage return.

       If a command in the file is prefixed with '-', failure will not abort the startup.

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

       · 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
       NB: This parameter depends on a feature which is not available on all platforms.

          · Units: bool

          · Default: off

          · Flags:

       Enable kernel accept-filters.

   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.

   backend_local_error_holddown
          · Units: seconds

          · Default: 10.000

          · Minimum: 0.000

          · Flags: experimental

       When connecting to backends, certain error codes (EADDRNOTAVAIL, EACCESS, EPERM) signal  a
       local  resource shortage or configuration issue for which retrying connection attempts may
       worsen the situation due to the complexity of the operations involved in the kernel.  This
       parameter prevents repeated connection attempts for the configured duration.

   backend_remote_error_holddown
          · Units: seconds

          · Default: 0.250

          · Minimum: 0.000

          · Flags: experimental

       When  connecting  to  backends,  certain  error  codes  (ECONNREFUSED, ENETUNREACH) signal
       fundamental connection issues such as the backend not  accepting  connections  or  routing
       problems  for  which  repeated  connection  attempts are considered useless This parameter
       prevents repeated connection attempts for the configured duration.

   ban_cutoff
          · Units: bans

          · Default: 0

          · Minimum: 0

          · Flags: experimental

       Expurge long tail content from the cache to keep the number of bans below  this  value.  0
       disables.

       When  this  parameter is set to a non-zero value, the ban lurker continues to work the ban
       list as usual top to bottom, but when it reaches the  ban_cutoff-th  ban,  it  treats  all
       objects  as  if  they matched a ban and expurges them from cache. As actively used objects
       get tested against the ban list at request time and thus are likely to be associated  with
       bans  near  the top of the ban list, with ban_cutoff, least recently accessed objects (the
       "long tail") are removed.

       This parameter is a safety net to avoid bad response times due to  bans  being  tested  at
       lookup  time.  Setting a cutoff trades response time for cache efficiency. The recommended
       value is proportional to rate(bans_lurker_tests_tested) / n_objects while the  ban  lurker
       is working, which is the number of bans the system can sustain. The additional latency due
       to request ban testing is in the order of ban_cutoff / rate(bans_lurker_tests_tested). For
       example,  for  rate(bans_lurker_tests_tested)  =  2M/s and a tolerable latency of 100ms, a
       good value for ban_cutoff may be 200K.

   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.  Because many applications
       issue bans in bursts, this parameter holds the ban-lurker off  until  the  rush  is  over.
       This should be set to the approximate time which a ban-burst takes.

   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_holdoff
          · Units: seconds

          · Default: 0.010

          · Minimum: 0.000

          · Flags: experimental

       How long the ban lurker sleeps when giving way to lookup due to lock contention.

   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  -g  -O2  -fdebug-prefix-map=/build/varnish-POsogG/varnish-6.1.1=.
            -fstack-protector-strong -Wformat -Werror=format-security -fexcess-precision=standard
            -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_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.

   clock_step
          · Units: seconds

          · Default: 1.000

          · Minimum: 0.000

       How much observed clock step we are willing to accept before we panic.

   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

          drop_pools
                 Drop thread pools (testing)

          slow_acceptor
                 Slow down Acceptor

          h2_nocheck
                 Disable various H2 checks

          vmod_so_keep
                 Keep copied VMOD libraries

          processors
                 Fetch/Deliver processors

          protocol
                 Protocol debugging

   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.

   esi_iovs
          · Units: struct iovec

          · Default: 10

          · Minimum: 3

          · Maximum: 1024

          · Flags: wizard

       Number of io vectors to allocate on the thread workspace for ESI requests.

   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

          https_scheme
                 Also split https URIs

          http2  Support HTTP/2 protocol

          http_date_postel
                 Relax parsing of timestamps in HTTP headers

   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.

   h2_header_table_size
          · Units: bytes

          · Default: 4k

          · Minimum: 0b

       HTTP2 header table size.  This is the size  that  will  be  used  for  the  HPACK  dynamic
       decoding table.

   h2_initial_window_size
          · Units: bytes

          · Default: 65535b

          · Minimum: 0b

          · Maximum: 2147483647b

       HTTP2 initial flow control window size.

   h2_max_concurrent_streams
          · Units: streams

          · Default: 100

          · Minimum: 0

       HTTP2  Maximum  number  of concurrent streams.  This is the number of requests that can be
       active at the same time for a single HTTP2 connection.

   h2_max_frame_size
          · Units: bytes

          · Default: 16k

          · Minimum: 16k

          · Maximum: 16777215b

       HTTP2 maximum per frame payload size we are willing to accept.

   h2_max_header_list_size
          · Units: bytes

          · Default: 2147483647b

          · Minimum: 0b

       HTTP2 maximum size of an uncompressed header list.

   h2_rx_window_increment
          · Units: bytes

          · Default: 1M

          · Minimum: 1M

          · Maximum: 1G

          · Flags: wizard

       HTTP2 Receive Window Increments.  How big credits we send  in  WINDOW_UPDATE  frames  Only
       affects incoming request bodies (ie: POST, PUT etc.)

   h2_rx_window_low_water
          · Units: bytes

          · Default: 10M

          · Minimum: 65535b

          · Maximum: 1G

          · Flags: wizard

       HTTP2  Receive  Window  low  water mark.  We try to keep the window at least this big Only
       affects incoming request bodies (ie: POST, PUT etc.)

   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.

       When  gzip  support  is disabled the variables beresp.do_gzip and beresp.do_gunzip have no
       effect in VCL.

   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 response.  The  memory  for  the
       response  is  allocated  from  the  backend  workspace (param: workspace_backend) and this
       parameter limits how much of that the response is allowed to take up.

   idle_send_timeout
          · Units: seconds

          · Default: 60.000

          · Minimum: 0.000

          · Flags: delayed

       Send timeout for individual pieces of data on client  connections.  May  get  extended  if
       'send_timeout' applies.

       When this timeout is hit, the session is closed.

       See the man page for 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.

   max_retries
          · Units: retries

          · Default: 4

          · Minimum: 0

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

   max_vcl
          · Default: 100

          · Minimum: 0

       Threshold   of   loaded   VCL   programs.    (VCL  labels  are  not  counted.)   Parameter
       max_vcl_handling determines behaviour.

   max_vcl_handling
          · Default: 1

          · Minimum: 0

          · Maximum: 2

       Behaviour when attempting to exceed max_vcl loaded VCL.

       · 0 - Ignore max_vcl parameter.

       · 1 - Issue warning.

       · 2 - Refuse loading VCLs.

   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

       Total  timeout  for  ordinary HTTP1 responses. Does not apply to some internally generated
       errors and pipe mode.

       When 'idle_send_timeout' is hit while sending an HTTP1 response, the timeout  is  extended
       unless  the total time already taken for sending the response in its entirety exceeds this
       many seconds.

       When this timeout is hit, the session is closed

   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_fastopen
          · Units: bool

          · Default: off

          · Flags: must_restart

       Enable TCP Fast Open extension.

   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. Ignored for Unix domain sockets.

   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. Ignored for Unix domain sockets.

   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. Ignored for Unix domain sockets.

   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 insufficient 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.  The  minimum  value depends on
       thread_pool_min.

       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.  The  maximum  value depends on
       thread_pool_max.

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

       Minimum is 10 threads.

   thread_pool_reserve
          · Units: threads

          · Default: 0

          · Maximum: 95

          · Flags: delayed

       The number of worker threads reserved for vital tasks in each pool.

       Tasks  may  require  other  tasks  to  complete  (for example, client requests may require
       backend requests). This reserve is to ensure that such tasks still get to run  even  under
       high load.

       Increasing  the  reserve  may  help  setups  with a high number of backend requests at the
       expense of client performance. Setting it too high will waste resources by keeping threads
       unused.

       Default  is  0  to  auto-tune  (currently 5% of thread_pool_min).  Minimum is 1 otherwise,
       maximum is 95% of thread_pool_min.

   thread_pool_stack
          · Units: bytes

          · Default: 48k

          · Minimum: 16k

          · Flags: delayed

       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.

       The required stack size is primarily driven by the depth of the call-tree. The most common
       relevant determining factors in varnish core code are GZIP (un)compression, ESI processing
       and  regular  expression matches. VMODs may also require significant amounts of additional
       stack.  The  nesting  depth  of  VCL  subs  is  another  factor,  although  typically  not
       predominant.

       The  stack  size  is  per  thread,  so the maximum total memory required for worker thread
       stacks is in the order of size = thread_pools x thread_pool_max x thread_pool_stack.

       Thus, in particular for setups with many threads, keeping the  stack  size  at  a  minimum
       helps reduce the amount of memory required by Varnish.

       On  the  other  hand,  thread_pool_stack  must  be  large  enough under all circumstances,
       otherwise varnish will crash due to a stack overflow. Usually, a stack overflow  manifests
       itself  as  a  segmentation fault (aka segfault / SIGSEGV) with the faulting address being
       near the stack pointer (sp).

       Unless stack usage can be reduced,  thread_pool_stack  must  be  increased  when  a  stack
       overflow  occurs.  Setting it in 150%-200% increments is recommended until stack overflows
       cease to occur.

   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_pool_watchdog
          · Units: seconds

          · Default: 10.000

          · Minimum: 0.100

          · Flags: experimental

       Thread queue stuck watchdog.

       If no queued work have been released for this long, the worker process panics itself.

   thread_pools
          · Units: pools

          · Default: 2

          · Minimum: 1

          · Maximum: 32

          · Flags: delayed, experimental

       Number of worker thread pools.

       Increasing the number of worker pools decreases lock contention. Each worker pool also has
       a thread accepting new connections, so for very high rates of incoming new connections  on
       systems with many cores, increasing the worker pools may be required.

       Too  many  pools  waste CPU and RAM resources, and more than one pool for each CPU is most
       likely detrimental 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 request 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.

       This parameter is particularly relevant for HTTP1 keepalive  connections which are  closed
       unless the next request is received before this timeout is reached.

   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:/usr/share/varnish/vcl

       Old name for vcl_path, use that instead.

   vcl_path
          · Default: /etc/varnish:/usr/share/varnish/vcl

       Directory (or colon separated list of  directories)  from  which  relative  VCL  filenames
       (vcl.load and include) are to be found.  By default Varnish searches VCL files in both the
       system configuration and shared data directories to allow packages to drop their VCL files
       in a standard location where relative includes would work.

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

       Old name for vmod_path, use that instead.

   vmod_path
          · 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.  When this parameter
       is adjusted, most likely workspace_client and workspace_backend will have to  be  adjusted
       by the same amount.

       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:
            -ObjProtocol,-ObjStatus,-ObjReason,-ObjHeader,-VCL_trace,-WorkThread,-Hash,-VfpAcct,-H2RxHdr,-H2RxBody,-H2TxHdr,-H2TxBody

       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

          · Maximum: 4G

          · 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_free_cooldown
          · Units: seconds

          · Default: 60.000

          · Minimum: 10.000

          · Maximum: 600.000

       How long VSM memory is  kept  warm  after  a  deallocation  (granularity  approximately  2
       seconds).

   vsm_space
          · Units: bytes

          · Default: 1M

          · Minimum: 1M

          · Maximum: 1G

       DEPRECATED:  This  parameter  is  ignored.   There  is no global limit on amount of shared
       memory now.

   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.  Use a multiple of 4k for VM
       efficiency.  For HTTP/2 compliance this must be at least 20k, in order to receive fullsize
       (=16k)  frames from the client.   That usually happens only in POST/PUT bodies.  For other
       traffic-patterns smaller values work just fine.

   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
       used  during  delivery. Setting this parameter too low may increase the number of writev()
       syscalls, setting it too high just wastes  space.   ~0.1k  +  UIO_MAXIOV  *  sizeof(struct
       iovec)  (typically  =  ~16k  for 64bit) is considered the maximum sensible value under any
       known circumstances (excluding exotic vmod use).

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.

COPYRIGHT

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

       · Copyright (c) 2007-2015 Varnish Software AS

                                                                                      VARNISHD(1)