1VARNISHD(1) VARNISHD(1)
2
6 varnishd - HTTP accelerator daemon
7
9 varnishd
10 [-a [name=][listen_address[,PROTO]] [-b [host[:port]|path]] [-C]
11 [-d] [-F] [-f config] [-h type[,options]] [-I clifile] [-i iden‐
12 tity] [-j jail[,jailoptions]] [-l vsl] [-M address:port] [-n
13 workdir] [-P file] [-p param=value] [-r param[,param...]] [-S
14 secret-file] [-s [name=]kind[,options]] [-T address[:port]] [-t
15 TTL] [-V] [-W waiter]
16 varnishd [-x parameter|vsl|cli|builtin|optstring]
18 varnishd [-?]
20
22 The varnishd daemon accepts HTTP requests from clients, passes them on
23 to a backend server and caches the returned documents to better satisfy
24 future requests for the same document.
25
27 Basic options
28 -a <[name=][listen_address[,PROTO]]>
29 Accept for client requests on the specified listen_address (see
30 below).
31 Name is referenced in logs. If name is not specified, "a0",
33 "a1", etc. is used.
34 PROTO can be "HTTP" (the default) or "PROXY". Both version 1
36 and 2 of the proxy protocol can be used.
37 Multiple -a arguments are allowed.
39 If no -a argument is given, the default -a :80 will listen to
41 all IPv4 and IPv6 interfaces.
42 -a <[name=][ip_address][:port][,PROTO]>
44 The ip_address can be a host name ("localhost"), an IPv4 dot‐
45 ted-quad ("127.0.0.1") or an IPv6 address enclosed in square
46 brackets ("[::1]")
47 If port is not specified, port 80 (http) is used.
49 At least one of ip_address or port is required.
51 -a <[name=][path][,PROTO][,user=name][,group=name][,mode=octal]>
53 (VCL4.1 and higher)
54 Accept connections on a Unix domain socket. Path must be abso‐
56 lute ("/path/to/listen.sock").
57 The user, group and mode sub-arguments may be used to specify
59 the permissions of the socket file -- use names for user and
60 group, and a 3-digit octal value for mode.
61 -b <[host[:port]|path]>
63 Use the specified host as backend server. If port is not speci‐
64 fied, the default is 8080.
65 If the value of -b begins with /, it is interpreted as the abso‐
67 lute path of a Unix domain socket to which Varnish connects. In
68 that case, the value of -b must satisfy the conditions required
69 for the .path field of a backend declaration, see vcl(7). Back‐
70 ends with Unix socket addresses may only be used with VCL ver‐
71 sions >= 4.1.
72 -b can be used only once, and not together with f.
74 -f config
76 Use the specified VCL configuration file instead of the builtin
77 default. See vcl(7) for details on VCL syntax.
78 If a single -f option is used, then the VCL instance loaded from
80 the file is named "boot" and immediately becomes active. If more
81 than one -f option is used, the VCL instances are named "boot0",
82 "boot1" and so forth, in the order corresponding to the -f argu‐
83 ments, and the last one is named "boot", which becomes active.
84 Either -b or one or more -f options must be specified, but not
86 both, and they cannot both be left out, unless -d is used to
87 start varnishd in debugging mode. If the empty string is speci‐
88 fied as the sole -f option, then varnishd starts without start‐
89 ing the worker process, and the management process will accept
90 CLI commands. You can also combine an empty -f option with an
91 initialization script (-I option) and the child process will be
92 started if there is an active VCL at the end of the initializa‐
93 tion.
94 When used with a relative file name, config is searched in the
96 vcl_path. It is possible to set this path prior to using -f op‐
97 tions with a -p option. During startup, varnishd doesn't com‐
98 plain about unsafe VCL paths: unlike the varnish-cli(7) that
99 could later be accessed remotely, starting varnishd requires lo‐
100 cal privileges.
101 -n workdir
103 Runtime directory for the shared memory, compiled VCLs etc.
104 In performance critical applications, this directory should be
106 on a RAM backed filesystem.
107 Relative paths will be appended to /var/run/ (NB: Binary pack‐
109 ages of Varnish may have adjusted this to the platform.)
110 The default value is /var/run/varnishd (NB: as above.)
112 Documentation options
114 For these options, varnishd prints information to standard output and
115 exits. When a -x option is used, it must be the only option (it outputs
116 documentation in reStructuredText, aka RST).
117 -?
119 Print the usage message.
120 -x parameter
122 Print documentation of the runtime parameters (-p options), see
123 List of Parameters.
124 -x vsl Print documentation of the tags used in the Varnish shared mem‐
126 ory log, see vsl(7).
127 -x cli Print documentation of the command line interface, see var‐
129 nish-cli(7).
130 -x builtin
132 Print the contents of the default VCL program builtin.vcl.
133 -x optstring
135 Print the optstring parameter to getopt(3) to help writing wrap‐
136 per scripts.
137 Operations options
139 -F Do not fork, run in the foreground. Only one of -F or -d can be
140 specified, and -F cannot be used together with -C.
141 -T <address[:port]>
143 Offer a management interface on the specified address and port.
144 See varnish-cli(7) for documentation of the management commands.
145 To disable the management interface use none.
146 -M <address:port>
148 Connect to this port and offer the command line interface.
149 Think of it as a reverse shell. When running with -M and there
150 is no backend defined the child process (the cache) will not
151 start initially.
152 -P file
154 Write the PID of the process to the specified file.
155 -i identity
157 Specify the identity of the Varnish server. This can be accessed
158 using server.identity from VCL and with VSM_Name() from utili‐
159 ties. If not specified the output of gethostname(3) is used.
160 -I clifile
162 Execute the management commands in the file given as clifile be‐
163 fore the the worker process starts, see CLI Command File.
164 Tuning options
166 -t TTL Specifies the default time to live (TTL) for cached objects.
167 This is a shortcut for specifying the default_ttl run-time pa‐
168 rameter.
169 -p <param=value>
171 Set the parameter specified by param to the specified value, see
172 List of Parameters for details. This option can be used multiple
173 times to specify multiple parameters.
174 -s <[name=]type[,options]>
176 Use the specified storage backend. See Storage Backend section.
177 This option can be used multiple times to specify multiple stor‐
179 age files. Name is referenced in logs, VCL, statistics, etc. If
180 name is not specified, "s0", "s1" and so forth is used.
181 -l <vsl>
183 Specifies size of the space for the VSL records, shorthand for
184 -p vsl_space=<vsl>. Scaling suffixes like 'K' and 'M' can be
185 used up to (G)igabytes. See vsl_space for more information.
186 Security options
188 -r <param[,param...]>
189 Make the listed parameters read only. This gives the system ad‐
190 ministrator a way to limit what the Varnish CLI can do. Con‐
191 sider making parameters such as cc_command, vcc_allow_inline_c
192 and vmod_path read only as these can potentially be used to es‐
193 calate privileges from the CLI.
194 -S secret-file
196 Path to a file containing a secret used for authorizing access
197 to the management port. To disable authentication use none.
198 If this argument is not provided, a secret drawn from the system
200 PRNG will be written to a file called _.secret in the working
201 directory (see opt_n) with default ownership and permissions of
202 the user having started varnish.
203 Thus, users wishing to delegate control over varnish will proba‐
205 bly want to create a custom secret file with appropriate permis‐
206 sions (ie. readable by a unix group to delegate control to).
207 -j <jail[,jailoptions]>
209 Specify the jailing mechanism to use. See Jail section.
210 Advanced, development and debugging options
212 -d Enables debugging mode: The parent process runs in the fore‐
213 ground with a CLI connection on stdin/stdout, and the child
214 process must be started explicitly with a CLI command. Terminat‐
215 ing the parent process will also terminate the child.
216 Only one of -d or -F can be specified, and -d cannot be used to‐
218 gether with -C.
219 -C Print VCL code compiled to C language and exit. Specify the VCL
221 file to compile with the -f option. Either -f or -b must be used
222 with -C, and -C cannot be used with -F or -d.
223 -V Display the version number and exit. This must be the only op‐
225 tion.
226 -h <type[,options]>
228 Specifies the hash algorithm. See Hash Algorithm section for a
229 list of supported algorithms.
230 -W waiter
232 Specifies the waiter type to use.
233 Hash Algorithm
235 The following hash algorithms are available:
236 -h critbit
238 self-scaling tree structure. The default hash algorithm in Var‐
239 nish Cache 2.1 and onwards. In comparison to a more traditional
240 B tree the critbit tree is almost completely lockless. Do not
241 change this unless you are certain what you're doing.
242 -h simple_list
244 A simple doubly-linked list. Not recommended for production
245 use.
246 -h <classic[,buckets]>
248 A standard hash table. The hash key is the CRC32 of the object's
249 URL modulo the size of the hash table. Each table entry points
250 to a list of elements which share the same hash key. The buckets
251 parameter specifies the number of entries in the hash table.
252 The default is 16383.
253 Storage Backend
255 The argument format to define storage backends is:
256 -s <[name]=kind[,options]>
258 If name is omitted, Varnish will name storages sN, starting with
259 s0 and incrementing N for every new storage.
260 For kind and options see details below.
262 Storages can be used in vcl as storage.name, so, for example if myStor‐
264 age was defined by -s myStorage=malloc,5G, it could be used in VCL like
265 so:
266 set beresp.storage = storage.myStorage;
268 A special name is Transient which is the default storage for un‐
270 cacheable objects as resulting from a pass, hit-for-miss or
271 hit-for-pass.
272 If no -s options are given, the default is:
274 -s default,100m
276 If no Transient storage is defined, the default is an unbound default
278 storage as if defined as:
279 -s Transient=default
281 The following storage types and options are available:
283 -s <default[,size]>
285 The default storage type resolves to umem where available and
286 malloc otherwise.
287 -s <malloc[,size]>
289 malloc is a memory based backend.
290 -s <umem[,size]>
292 umem is a storage backend which is more efficient than malloc on
293 platforms where it is available.
294 See the section on umem in chapter Storage backends of The Var‐
296 nish Users Guide for details.
297 -s <file,path[,size[,granularity[,advice]]]>
299 The file backend stores data in a file on disk. The file will be
300 accessed using mmap. Note that this storage provide no cache
301 persistence.
302 The path is mandatory. If path points to a directory, a tempo‐
304 rary file will be created in that directory and immediately un‐
305 linked. If path points to a non-existing file, the file will be
306 created.
307 If size is omitted, and path points to an existing file with a
309 size greater than zero, the size of that file will be used. If
310 not, an error is reported.
311 Granularity sets the allocation block size. Defaults to the sys‐
313 tem page size or the filesystem block size, whichever is larger.
314 Advice tells the kernel how varnishd expects to use this mapped
316 region so that the kernel can choose the appropriate read-ahead
317 and caching techniques. Possible values are normal, random and
318 sequential, corresponding to MADV_NORMAL, MADV_RANDOM and
319 MADV_SEQUENTIAL madvise() advice argument, respectively. De‐
320 faults to random.
321 -s <persistent,path,size>
323 Persistent storage. Varnish will store objects in a file in a
324 manner that will secure the survival of most of the objects in
325 the event of a planned or unplanned shutdown of Varnish. The
326 persistent storage backend has multiple issues with it and will
327 likely be removed from a future version of Varnish.
328 Jail
330 Varnish jails are a generalization over various platform specific meth‐
331 ods to reduce the privileges of varnish processes. They may have spe‐
332 cific options. Available jails are:
333 -j <solaris[,worker=`privspec`]>
335 Reduce privileges(5) for varnishd and sub-process to the mini‐
336 mally required set. Only available on platforms which have the
337 setppriv(2) call.
338 The optional worker argument can be used to pass a privi‐
340 lege-specification (see ppriv(1)) by which to extend the effec‐
341 tive set of the varnish worker process. While extended privi‐
342 leges may be required by custom vmods, it is always the more se‐
343 cure to not use the worker option.
344 Example to grant basic privileges to the worker process:
346 -j solaris,worker=basic
348 -j <unix[,user=`user`][,ccgroup=`group`][,workuser=`user`]>
350 Default on all other platforms when varnishd is started with an
351 effective uid of 0 ("as root").
352 With the unix jail mechanism activated, varnish will switch to
354 an alternative user for subprocesses and change the effective
355 uid of the master process whenever possible.
356 The optional user argument specifies which alternative user to
358 use. It defaults to varnish.
359 The optional ccgroup argument specifies a group to add to var‐
361 nish subprocesses requiring access to a c-compiler. There is no
362 default.
363 The optional workuser argument specifies an alternative user to
365 use for the worker process. It defaults to vcache.
366 -j none
368 last resort jail choice: With jail mechanism none, varnish will
369 run all processes with the privileges it was started with.
370 Management Interface
372 If the -T option was specified, varnishd will offer a command-line man‐
373 agement interface on the specified address and port. The recommended
374 way of connecting to the command-line management interface is through
375 varnishadm(1).
376 The commands available are documented in varnish-cli(7).
378 CLI Command File
380 The -I option makes it possible to run arbitrary management commands
381 when varnishd is launched, before the worker process is started. In
382 particular, this is the way to load configurations, apply labels to
383 them, and make a VCL instance active that uses those labels on startup:
384 vcl.load panic /etc/varnish_panic.vcl
386 vcl.load siteA0 /etc/varnish_siteA.vcl
387 vcl.load siteB0 /etc/varnish_siteB.vcl
388 vcl.load siteC0 /etc/varnish_siteC.vcl
389 vcl.label siteA siteA0
390 vcl.label siteB siteB0
391 vcl.label siteC siteC0
392 vcl.load main /etc/varnish_main.vcl
393 vcl.use main
394 Every line in the file, including the last line, must be terminated by
396 a newline or carriage return.
397 If a command in the file is prefixed with '-', failure will not abort
399 the startup.
400 Note that it is necessary to include an explicit vcl.use command to se‐
402 lect which VCL should be the active VCL when relying on CLI Command
403 File to load the configurations at startup.
404
406 Run Time Parameter Flags
407 Runtime parameters are marked with shorthand flags to avoid repeating
408 the same text over and over in the table below. The meaning of the
409 flags are:
410 • experimental
412 We have no solid information about good/bad/optimal values for this
414 parameter. Feedback with experience and observations are most wel‐
415 come.
416 • delayed
418 This parameter can be changed on the fly, but will not take effect
420 immediately.
421 • restart
423 The worker process must be stopped and restarted, before this parame‐
425 ter takes effect.
426 • reload
428 The VCL programs must be reloaded for this parameter to take effect.
430 • wizard
432 Do not touch unless you really know what you're doing.
434 • only_root
436 Only works if varnishd is running as root.
438 Default Value Exceptions on 32 bit Systems
440 Be aware that on 32 bit systems, certain default or maximum values are
441 reduced relative to the values listed below, in order to conserve VM
442 space:
443 • workspace_client: 24k
445 • workspace_backend: 20k
447 • http_resp_size: 8k
449 • http_req_size: 12k
451 • gzip_buffer: 4k
453 • vsl_buffer: 4k
455 • vsl_space: 1G (maximum)
457 • thread_pool_stack: 64k
459 List of Parameters
461 This text is produced from the same text you will find in the CLI if
462 you use the param.show command:
463 accept_filter
465 NB: This parameter depends on a feature which is not available on all
466 platforms.
467 • Units: bool
469 • Default: on (if your platform supports accept filters)
471 Enable kernel accept-filters. This may require a kernel module to be
473 loaded to have an effect when enabled.
474 Enabling accept_filter may prevent some requests to reach Varnish in
476 the first place. Malformed requests may go unnoticed and not increase
477 the client_req_400 counter. GET or HEAD requests with a body may be
478 blocked altogether.
479 acceptor_sleep_decay
481 • Default: 0.9
482 • Minimum: 0
484 • Maximum: 1
486 • Flags: experimental
488 If we run out of resources, such as file descriptors or worker threads,
490 the acceptor will sleep between accepts. This parameter (multiplica‐
491 tively) reduce the sleep duration for each successful accept. (ie: 0.9
492 = reduce by 10%)
493 acceptor_sleep_incr
495 • Units: seconds
496 • Default: 0.000
498 • Minimum: 0.000
500 • Maximum: 1.000
502 • Flags: experimental
504 If we run out of resources, such as file descriptors or worker threads,
506 the acceptor will sleep between accepts. This parameter control how
507 much longer we sleep, each time we fail to accept a new connection.
508 acceptor_sleep_max
510 • Units: seconds
511 • Default: 0.050
513 • Minimum: 0.000
515 • Maximum: 10.000
517 • Flags: experimental
519 If we run out of resources, such as file descriptors or worker threads,
521 the acceptor will sleep between accepts. This parameter limits how
522 long it can sleep between attempts to accept new connections.
523 auto_restart
525 • Units: bool
526 • Default: on
528 Automatically restart the child/worker process if it dies.
530 backend_idle_timeout
532 • Units: seconds
533 • Default: 60.000
535 • Minimum: 1.000
537 Timeout before we close unused backend connections.
539 backend_local_error_holddown
541 • Units: seconds
542 • Default: 10.000
544 • Minimum: 0.000
546 • Flags: experimental
548 When connecting to backends, certain error codes (EADDRNOTAVAIL, EAC‐
550 CESS, EPERM) signal a local resource shortage or configuration issue
551 for which retrying connection attempts may worsen the situation due to
552 the complexity of the operations involved in the kernel. This parame‐
553 ter prevents repeated connection attempts for the configured duration.
554 backend_remote_error_holddown
556 • Units: seconds
557 • Default: 0.250
559 • Minimum: 0.000
561 • Flags: experimental
563 When connecting to backends, certain error codes (ECONNREFUSED, ENETUN‐
565 REACH) signal fundamental connection issues such as the backend not ac‐
566 cepting connections or routing problems for which repeated connection
567 attempts are considered useless This parameter prevents repeated con‐
568 nection attempts for the configured duration.
569 ban_cutoff
571 • Units: bans
572 • Default: 0
574 • Minimum: 0
576 • Flags: experimental
578 Expurge long tail content from the cache to keep the number of bans be‐
580 low this value. 0 disables.
581 When this parameter is set to a non-zero value, the ban lurker contin‐
583 ues to work the ban list as usual top to bottom, but when it reaches
584 the ban_cutoff-th ban, it treats all objects as if they matched a ban
585 and expurges them from cache. As actively used objects get tested
586 against the ban list at request time and thus are likely to be associ‐
587 ated with bans near the top of the ban list, with ban_cutoff, least re‐
588 cently accessed objects (the "long tail") are removed.
589 This parameter is a safety net to avoid bad response times due to bans
591 being tested at lookup time. Setting a cutoff trades response time for
592 cache efficiency. The recommended value is proportional to
593 rate(bans_lurker_tests_tested) / n_objects while the ban lurker is
594 working, which is the number of bans the system can sustain. The addi‐
595 tional latency due to request ban testing is in the order of ban_cutoff
596 / rate(bans_lurker_tests_tested). For example, for
597 rate(bans_lurker_tests_tested) = 2M/s and a tolerable latency of 100ms,
598 a good value for ban_cutoff may be 200K.
599 ban_dups
601 • Units: bool
602 • Default: on
604 Eliminate older identical bans when a new ban is added. This saves CPU
606 cycles by not comparing objects to identical bans. This is a waste of
607 time if you have many bans which are never identical.
608 ban_lurker_age
610 • Units: seconds
611 • Default: 60.000
613 • Minimum: 0.000
615 The ban lurker will ignore bans until they are this old. When a ban is
617 added, the active traffic will be tested against it as part of object
618 lookup. Because many applications issue bans in bursts, this parameter
619 holds the ban-lurker off until the rush is over. This should be set to
620 the approximate time which a ban-burst takes.
621 ban_lurker_batch
623 • Default: 1000
624 • Minimum: 1
626 The ban lurker sleeps ${ban_lurker_sleep} after examining this many ob‐
628 jects. Use this to pace the ban-lurker if it eats too many resources.
629 ban_lurker_holdoff
631 • Units: seconds
632 • Default: 0.010
634 • Minimum: 0.000
636 • Flags: experimental
638 How long the ban lurker sleeps when giving way to lookup due to lock
640 contention.
641 ban_lurker_sleep
643 • Units: seconds
644 • Default: 0.010
646 • Minimum: 0.000
648 How long the ban lurker sleeps after examining ${ban_lurker_batch} ob‐
650 jects. Use this to pace the ban-lurker if it eats too many resources.
651 A value of zero will disable the ban lurker entirely.
652 between_bytes_timeout
654 • Units: seconds
655 • Default: 60.000
657 • Minimum: 0.000
659 We only wait for this many seconds between bytes received from the
661 backend before giving up the fetch. VCL values, per backend or per
662 backend request take precedence. This parameter does not apply to
663 pipe'ed requests.
664 cc_command
666 • Default: exec clang -g -O2 -Wall -Werror -Wno-error=unused-result
667 -fstack-protector-strong -Werror -Wall -Wcast-align -Wcast-qual
668 -Wchar-subscripts -Wempty-body -Wextra -Wformat -Wformat-y2k
669 -Wformat -Wformat-zero-length -Wmissing-field-initializers -Wmiss‐
670 ing-prototypes -Wnested-externs -Wpointer-arith -Wpointer-sign
671 -Wreturn-type -Wshadow -Wstrict-aliasing -Wstrict-prototypes
672 -Wstring-plus-int -Wswitch -Wunused-parameter -Wunused-result
673 -Wwrite-strings -Wno-old-style-definition -Wno-sign-compare
674 -Wno-implicit-fallthrough -Wno-missing-variable-declarations
675 -Wno-nullability-completeness -fstack-protector -Wno-miss‐
676 ing-field-initializers -pthread -fpic -shared -Wl,-x -o %o %s
677 • Flags: must_reload
679 Command used for compiling the C source code to a dlopen(3) loadable
681 object. Any occurrence of %s in the string will be replaced with the
682 source file name, and %o will be replaced with the output file name.
683 cli_limit
685 • Units: bytes
686 • Default: 48k
688 • Minimum: 128b
690 • Maximum: 99999999b
692 Maximum size of CLI response. If the response exceeds this limit, the
694 response code will be 201 instead of 200 and the last line will indi‐
695 cate the truncation.
696 cli_timeout
698 • Units: seconds
699 • Default: 60.000
701 • Minimum: 0.000
703 Timeout for the childs replies to CLI requests from the mgt_param.
705 clock_skew
707 • Units: seconds
708 • Default: 10
710 • Minimum: 0
712 How much clockskew we are willing to accept between the backend and our
714 own clock.
715 clock_step
717 • Units: seconds
718 • Default: 1.000
720 • Minimum: 0.000
722 How much observed clock step we are willing to accept before we panic.
724 connect_timeout
726 • Units: seconds
727 • Default: 3.500
729 • Minimum: 0.000
731 Default connection timeout for backend connections. We only try to con‐
733 nect to the backend for this many seconds before giving up. VCL can
734 override this default value for each backend and backend request.
735 critbit_cooloff
737 • Units: seconds
738 • Default: 180.000
740 • Minimum: 60.000
742 • Maximum: 254.000
744 • Flags: wizard
746 How long the critbit hasher keeps deleted objheads on the cooloff list.
748 debug
750 • Default: none
751 Enable/Disable various kinds of debugging.
753 none Disable all debugging
755 Use +/- prefix to set/reset individual bits:
757 req_state
759 VSL Request state engine
760 workspace
762 VSL Workspace operations
763 waitinglist
765 VSL Waitinglist events
766 syncvsl
768 Make VSL synchronous
769 hashedge
771 Edge cases in Hash
772 vclrel Rapid VCL release
774 lurker VSL Ban lurker
776 esi_chop
778 Chop ESI fetch to bits
779 flush_head
781 Flush after http1 head
782 vtc_mode
784 Varnishtest Mode
785 witness
787 Emit WITNESS lock records
788 vsm_keep
790 Keep the VSM file on restart
791 drop_pools
793 Drop thread pools (testing)
794 slow_acceptor
796 Slow down Acceptor
797 h2_nocheck
799 Disable various H2 checks
800 vmod_so_keep
802 Keep copied VMOD libraries
803 processors
805 Fetch/Deliver processors
806 protocol
808 Protocol debugging
809 vcl_keep
811 Keep VCL C and so files
812 lck Additional lock statistics
814 default_grace
816 • Units: seconds
817 • Default: 10.000
819 • Minimum: 0.000
821 • Flags: obj_sticky
823 Default grace period. We will deliver an object this long after it has
825 expired, provided another thread is attempting to get a new copy.
826 default_keep
828 • Units: seconds
829 • Default: 0.000
831 • Minimum: 0.000
833 • Flags: obj_sticky
835 Default keep period. We will keep a useless object around this long,
837 making it available for conditional backend fetches. That means that
838 the object will be removed from the cache at the end of ttl+grace+keep.
839 default_ttl
841 • Units: seconds
842 • Default: 120.000
844 • Minimum: 0.000
846 • Flags: obj_sticky
848 The TTL assigned to objects if neither the backend nor the VCL code as‐
850 signs one.
851 feature
853 • Default: +validate_headers
854 Enable/Disable various minor features.
856 default
858 Set default value
859 none Disable all features.
861 Use +/- prefix to enable/disable individual feature:
863 http2 Enable HTTP/2 protocol support.
865 short_panic
867 Short panic message.
868 no_coredump
870 No coredumps. Must be set before child process starts.
871 https_scheme
873 Extract host from full URI in the HTTP/1 request line, if the
874 scheme is https.
875 http_date_postel
877 Tolerate non compliant timestamp headers like Date, Last-Mod‐
878 ified, Expires etc.
879 esi_ignore_https
881 Convert <esi:include src"https://... to http://...
882 esi_disable_xml_check
884 Allow ESI processing on non-XML ESI bodies
885 esi_ignore_other_elements
887 Ignore XML syntax errors in ESI bodies.
888 esi_remove_bom
890 Ignore UTF-8 BOM in ESI bodies.
891 wait_silo
893 Wait for persistent silos to completely load before serving
894 requests.
895 validate_headers
897 Validate all header set operations to conform to RFC7230.
898 busy_stats_rate
900 Make busy workers comply with thread_stats_rate.
901 fetch_chunksize
903 • Units: bytes
904 • Default: 16k
906 • Minimum: 4k
908 • Flags: experimental
910 The default chunksize used by fetcher. This should be bigger than the
912 majority of objects with short TTLs. Internal limits in the stor‐
913 age_file module makes increases above 128kb a dubious idea.
914 fetch_maxchunksize
916 • Units: bytes
917 • Default: 0.25G
919 • Minimum: 64k
921 • Flags: experimental
923 The maximum chunksize we attempt to allocate from storage. Making this
925 too large may cause delays and storage fragmentation.
926 first_byte_timeout
928 • Units: seconds
929 • Default: 60.000
931 • Minimum: 0.000
933 Default timeout for receiving first byte from backend. We only wait for
935 this many seconds for the first byte before giving up. VCL can over‐
936 ride this default value for each backend and backend request. This pa‐
937 rameter does not apply to pipe'ed requests.
938 gzip_buffer
940 • Units: bytes
941 • Default: 32k
943 • Minimum: 2k
945 • Flags: experimental
947 Size of malloc buffer used for gzip processing. These buffers are used
949 for in-transit data, for instance gunzip'ed data being sent to a
950 client.Making this space to small results in more overhead, writes to
951 sockets etc, making it too big is probably just a waste of memory.
952 gzip_level
954 • Default: 6
955 • Minimum: 0
957 • Maximum: 9
959 Gzip compression level: 0=debug, 1=fast, 9=best
961 gzip_memlevel
963 • Default: 8
964 • Minimum: 1
966 • Maximum: 9
968 Gzip memory level 1=slow/least, 9=fast/most compression. Memory impact
970 is 1=1k, 2=2k, ... 9=256k.
971 h2_header_table_size
973 • Units: bytes
974 • Default: 4k
976 • Minimum: 0b
978 HTTP2 header table size. This is the size that will be used for the
980 HPACK dynamic decoding table.
981 h2_initial_window_size
983 • Units: bytes
984 • Default: 65535b
986 • Minimum: 65535b
988 • Maximum: 2147483647b
990 HTTP2 initial flow control window size.
992 h2_max_concurrent_streams
994 • Units: streams
995 • Default: 100
997 • Minimum: 0
999 HTTP2 Maximum number of concurrent streams. This is the number of re‐
1001 quests that can be active at the same time for a single HTTP2 connec‐
1002 tion.
1003 h2_max_frame_size
1005 • Units: bytes
1006 • Default: 16k
1008 • Minimum: 16k
1010 • Maximum: 16777215b
1012 HTTP2 maximum per frame payload size we are willing to accept.
1014 h2_max_header_list_size
1016 • Units: bytes
1017 • Default: 2147483647b
1019 • Minimum: 0b
1021 HTTP2 maximum size of an uncompressed header list.
1023 h2_rx_window_increment
1025 • Units: bytes
1026 • Default: 1M
1028 • Minimum: 1M
1030 • Maximum: 1G
1032 • Flags: wizard
1034 HTTP2 Receive Window Increments. How big credits we send in WINDOW_UP‐
1036 DATE frames Only affects incoming request bodies (ie: POST, PUT etc.)
1037 h2_rx_window_low_water
1039 • Units: bytes
1040 • Default: 10M
1042 • Minimum: 65535b
1044 • Maximum: 1G
1046 • Flags: wizard
1048 HTTP2 Receive Window low water mark. We try to keep the window at
1050 least this big Only affects incoming request bodies (ie: POST, PUT
1051 etc.)
1052 h2_rxbuf_storage
1054 • Default: Transient
1055 • Flags: must_restart
1057 The name of the storage backend that HTTP/2 receive buffers should be
1059 allocated from.
1060 http1_iovs
1062 • Units: struct iovec (=16 bytes)
1063 • Default: 64
1065 • Minimum: 5
1067 • Maximum: 1024
1069 • Flags: wizard
1071 Number of io vectors to allocate for HTTP1 protocol transmission. A
1073 HTTP1 header needs 7 + 2 per HTTP header field. Allocated from
1074 workspace_thread.
1075 http_gzip_support
1077 • Units: bool
1078 • Default: on
1080 Enable gzip support. When enabled Varnish request compressed objects
1082 from the backend and store them compressed. If a client does not sup‐
1083 port gzip encoding Varnish will uncompress compressed objects on de‐
1084 mand. Varnish will also rewrite the Accept-Encoding header of clients
1085 indicating support for gzip to:
1086 Accept-Encoding: gzip
1087 Clients that do not support gzip will have their Accept-Encoding header
1089 removed. For more information on how gzip is implemented please see the
1090 chapter on gzip in the Varnish reference.
1091 When gzip support is disabled the variables beresp.do_gzip and
1093 beresp.do_gunzip have no effect in VCL.
1094 http_max_hdr
1096 • Units: header lines
1097 • Default: 64
1099 • Minimum: 32
1101 • Maximum: 65535
1103 Maximum number of HTTP header lines we allow in
1105 {req|resp|bereq|beresp}.http (obj.http is autosized to the exact number
1106 of headers). Cheap, ~20 bytes, in terms of workspace memory. Note
1107 that the first line occupies five header lines.
1108 http_range_support
1110 • Units: bool
1111 • Default: on
1113 Enable support for HTTP Range headers.
1115 http_req_hdr_len
1117 • Units: bytes
1118 • Default: 8k
1120 • Minimum: 40b
1122 Maximum length of any HTTP client request header we will allow. The
1124 limit is inclusive its continuation lines.
1125 http_req_size
1127 • Units: bytes
1128 • Default: 32k
1130 • Minimum: 0.25k
1132 Maximum number of bytes of HTTP client request we will deal with. This
1134 is a limit on all bytes up to the double blank line which ends the HTTP
1135 request. The memory for the request is allocated from the client
1136 workspace (param: workspace_client) and this parameter limits how much
1137 of that the request is allowed to take up.
1138 http_resp_hdr_len
1140 • Units: bytes
1141 • Default: 8k
1143 • Minimum: 40b
1145 Maximum length of any HTTP backend response header we will allow. The
1147 limit is inclusive its continuation lines.
1148 http_resp_size
1150 • Units: bytes
1151 • Default: 32k
1153 • Minimum: 0.25k
1155 Maximum number of bytes of HTTP backend response we will deal with.
1157 This is a limit on all bytes up to the double blank line which ends the
1158 HTTP response. The memory for the response is allocated from the back‐
1159 end workspace (param: workspace_backend) and this parameter limits how
1160 much of that the response is allowed to take up.
1161 idle_send_timeout
1163 • Units: seconds
1164 • Default: 60.000
1166 • Minimum: 0.000
1168 • Flags: delayed
1170 Send timeout for individual pieces of data on client connections. May
1172 get extended if 'send_timeout' applies.
1173 When this timeout is hit, the session is closed.
1175 See the man page for setsockopt(2) or socket(7) under SO_SNDTIMEO for
1177 more information.
1178 listen_depth
1180 • Units: connections
1181 • Default: 1024
1183 • Minimum: 0
1185 • Flags: must_restart
1187 Listen queue depth.
1189 lru_interval
1191 • Units: seconds
1192 • Default: 2.000
1194 • Minimum: 0.000
1196 • Flags: experimental
1198 Grace period before object moves on LRU list. Objects are only moved
1200 to the front of the LRU list if they have not been moved there already
1201 inside this timeout period. This reduces the amount of lock operations
1202 necessary for LRU list access.
1203 max_esi_depth
1205 • Units: levels
1206 • Default: 5
1208 • Minimum: 0
1210 Maximum depth of esi:include processing.
1212 max_restarts
1214 • Units: restarts
1215 • Default: 4
1217 • Minimum: 0
1219 Upper limit on how many times a request can restart.
1221 max_retries
1223 • Units: retries
1224 • Default: 4
1226 • Minimum: 0
1228 Upper limit on how many times a backend fetch can retry.
1230 max_vcl
1232 • Default: 100
1233 • Minimum: 0
1235 Threshold of loaded VCL programs. (VCL labels are not counted.) Pa‐
1237 rameter max_vcl_handling determines behaviour.
1238 max_vcl_handling
1240 • Default: 1
1241 • Minimum: 0
1243 • Maximum: 2
1245 Behaviour when attempting to exceed max_vcl loaded VCL.
1247 • 0 - Ignore max_vcl parameter.
1249 • 1 - Issue warning.
1251 • 2 - Refuse loading VCLs.
1253 nuke_limit
1255 • Units: allocations
1256 • Default: 50
1258 • Minimum: 0
1260 • Flags: experimental
1262 Maximum number of objects we attempt to nuke in order to make space for
1264 a object body.
1265 pcre2_depth_limit
1267 • Default: 20
1268 • Minimum: 1
1270 The recursion depth-limit for the internal match logic in a
1272 pcre2_match().
1273 (See: pcre2_set_depth_limit() in pcre2 docs.)
1275 This puts an upper limit on the amount of stack used by PCRE2 for cer‐
1277 tain classes of regular expressions.
1278 We have set the default value low in order to prevent crashes, at the
1280 cost of possible regexp matching failures.
1281 Matching failures will show up in the log as VCL_Error messages.
1283 pcre2_jit_compilation
1285 • Units: bool
1286 • Default: on
1288 Use the pcre2 JIT compiler if available.
1290 pcre2_match_limit
1292 • Default: 10000
1293 • Minimum: 1
1295 The limit for the number of calls to the internal match logic in
1297 pcre2_match().
1298 (See: pcre2_set_match_limit() in pcre2 docs.)
1300 This parameter limits how much CPU time regular expression matching can
1302 soak up.
1303 ping_interval
1305 • Units: seconds
1306 • Default: 3
1308 • Minimum: 0
1310 • Flags: must_restart
1312 Interval between pings from parent to child. Zero will disable pinging
1314 entirely, which makes it possible to attach a debugger to the child.
1315 pipe_sess_max
1317 • Units: connections
1318 • Default: 0
1320 • Minimum: 0
1322 Maximum number of sessions dedicated to pipe transactions.
1324 pipe_timeout
1326 • Units: seconds
1327 • Default: 60.000
1329 • Minimum: 0.000
1331 Idle timeout for PIPE sessions. If nothing have been received in either
1333 direction for this many seconds, the session is closed.
1334 pool_req
1336 • Default: 10,100,10
1337 Parameters for per worker pool request memory pool.
1339 The three numbers are:
1341 min_pool
1343 minimum size of free pool.
1344 max_pool
1346 maximum size of free pool.
1347 max_age
1349 max age of free element.
1350 pool_sess
1352 • Default: 10,100,10
1353 Parameters for per worker pool session memory pool.
1355 The three numbers are:
1357 min_pool
1359 minimum size of free pool.
1360 max_pool
1362 maximum size of free pool.
1363 max_age
1365 max age of free element.
1366 pool_vbo
1368 • Default: 10,100,10
1369 Parameters for backend object fetch memory pool.
1371 The three numbers are:
1373 min_pool
1375 minimum size of free pool.
1376 max_pool
1378 maximum size of free pool.
1379 max_age
1381 max age of free element.
1382 prefer_ipv6
1384 • Units: bool
1385 • Default: off
1387 Prefer IPv6 address when connecting to backends which have both IPv4
1389 and IPv6 addresses.
1390 rush_exponent
1392 • Units: requests per request
1393 • Default: 3
1395 • Minimum: 2
1397 • Flags: experimental
1399 How many parked request we start for each completed request on the ob‐
1401 ject. NB: Even with the implict delay of delivery, this parameter con‐
1402 trols an exponential increase in number of worker threads.
1403 send_timeout
1405 • Units: seconds
1406 • Default: 600.000
1408 • Minimum: 0.000
1410 • Flags: delayed
1412 Total timeout for ordinary HTTP1 responses. Does not apply to some in‐
1414 ternally generated errors and pipe mode.
1415 When 'idle_send_timeout' is hit while sending an HTTP1 response, the
1417 timeout is extended unless the total time already taken for sending the
1418 response in its entirety exceeds this many seconds.
1419 When this timeout is hit, the session is closed
1421 shortlived
1423 • Units: seconds
1424 • Default: 10.000
1426 • Minimum: 0.000
1428 Objects created with (ttl+grace+keep) shorter than this are always put
1430 in transient storage.
1431 sigsegv_handler
1433 • Units: bool
1434 • Default: on
1436 • Flags: must_restart
1438 Install a signal handler which tries to dump debug information on seg‐
1440 mentation faults, bus errors and abort signals.
1441 syslog_cli_traffic
1443 • Units: bool
1444 • Default: on
1446 Log all CLI traffic to syslog(LOG_INFO).
1448 tcp_fastopen
1450 NB: This parameter depends on a feature which is not available on all
1451 platforms.
1452 • Units: bool
1454 • Default: off
1456 • Flags: must_restart
1458 Enable TCP Fast Open extension.
1460 tcp_keepalive_intvl
1462 NB: This parameter depends on a feature which is not available on all
1463 platforms.
1464 • Units: seconds
1466 • Default: platform dependent
1468 • Minimum: 1.000
1470 • Maximum: 100.000
1472 • Flags: experimental
1474 The number of seconds between TCP keep-alive probes. Ignored for Unix
1476 domain sockets.
1477 tcp_keepalive_probes
1479 NB: This parameter depends on a feature which is not available on all
1480 platforms.
1481 • Units: probes
1483 • Default: platform dependent
1485 • Minimum: 1
1487 • Maximum: 100
1489 • Flags: experimental
1491 The maximum number of TCP keep-alive probes to send before giving up
1493 and killing the connection if no response is obtained from the other
1494 end. Ignored for Unix domain sockets.
1495 tcp_keepalive_time
1497 NB: This parameter depends on a feature which is not available on all
1498 platforms.
1499 • Units: seconds
1501 • Default: platform dependent
1503 • Minimum: 1.000
1505 • Maximum: 7200.000
1507 • Flags: experimental
1509 The number of seconds a connection needs to be idle before TCP begins
1511 sending out keep-alive probes. Ignored for Unix domain sockets.
1512 thread_pool_add_delay
1514 • Units: seconds
1515 • Default: 0.000
1517 • Minimum: 0.000
1519 • Flags: experimental
1521 Wait at least this long after creating a thread.
1523 Some (buggy) systems may need a short (sub-second) delay between creat‐
1525 ing threads. Set this to a few milliseconds if you see the
1526 'threads_failed' counter grow too much.
1527 Setting this too high results in insufficient worker threads.
1529 thread_pool_destroy_delay
1531 • Units: seconds
1532 • Default: 1.000
1534 • Minimum: 0.010
1536 • Flags: delayed, experimental
1538 Wait this long after destroying a thread.
1540 This controls the decay of thread pools when idle(-ish).
1542 thread_pool_fail_delay
1544 • Units: seconds
1545 • Default: 0.200
1547 • Minimum: 0.010
1549 • Flags: experimental
1551 Wait at least this long after a failed thread creation before trying to
1553 create another thread.
1554 Failure to create a worker thread is often a sign that the end is
1556 near, because the process is running out of some resource. This delay
1557 tries to not rush the end on needlessly.
1558 If thread creation failures are a problem, check that thread_pool_max
1560 is not too high.
1561 It may also help to increase thread_pool_timeout and thread_pool_min,
1563 to reduce the rate at which treads are destroyed and later recreated.
1564 thread_pool_max
1566 • Units: threads
1567 • Default: 5000
1569 • Minimum: thread_pool_min
1571 • Flags: delayed
1573 The maximum number of worker threads in each pool.
1575 Do not set this higher than you have to, since excess worker threads
1577 soak up RAM and CPU and generally just get in the way of getting work
1578 done.
1579 thread_pool_min
1581 • Units: threads
1582 • Default: 100
1584 • Minimum: 5
1586 • Maximum: thread_pool_max
1588 • Flags: delayed
1590 The minimum number of worker threads in each pool.
1592 Increasing this may help ramp up faster from low load situations or
1594 when threads have expired.
1595 Technical minimum is 5 threads, but this parameter is strongly recom‐
1597 mended to be at least 10
1598 thread_pool_reserve
1600 • Units: threads
1601 • Default: 0 (auto-tune: 5% of thread_pool_min)
1603 • Maximum: 95% of thread_pool_min
1605 • Flags: delayed
1607 The number of worker threads reserved for vital tasks in each pool.
1609 Tasks may require other tasks to complete (for example, client requests
1611 may require backend requests, http2 sessions require streams, which re‐
1612 quire requests). This reserve is to ensure that lower priority tasks do
1613 not prevent higher priority tasks from running even under high load.
1614 The effective value is at least 5 (the number of internal priority
1616 classes), irrespective of this parameter.
1617 thread_pool_stack
1619 • Units: bytes
1620 • Default: 80k
1622 • Minimum: sysconf(_SC_THREAD_STACK_MIN)
1624 • Flags: delayed
1626 Worker thread stack size. This will likely be rounded up to a multiple
1628 of 4k (or whatever the page_size might be) by the kernel.
1629 The required stack size is primarily driven by the depth of the
1631 call-tree. The most common relevant determining factors in varnish core
1632 code are GZIP (un)compression, ESI processing and regular expression
1633 matches. VMODs may also require significant amounts of additional
1634 stack. The nesting depth of VCL subs is another factor, although typi‐
1635 cally not predominant.
1636 The stack size is per thread, so the maximum total memory required for
1638 worker thread stacks is in the order of size = thread_pools x
1639 thread_pool_max x thread_pool_stack.
1640 Thus, in particular for setups with many threads, keeping the stack
1642 size at a minimum helps reduce the amount of memory required by Var‐
1643 nish.
1644 On the other hand, thread_pool_stack must be large enough under all
1646 circumstances, otherwise varnish will crash due to a stack overflow.
1647 Usually, a stack overflow manifests itself as a segmentation fault (aka
1648 segfault / SIGSEGV) with the faulting address being near the stack
1649 pointer (sp).
1650 Unless stack usage can be reduced, thread_pool_stack must be increased
1652 when a stack overflow occurs. Setting it in 150%-200% increments is
1653 recommended until stack overflows cease to occur.
1654 thread_pool_timeout
1656 • Units: seconds
1657 • Default: 300.000
1659 • Minimum: 10.000
1661 • Flags: delayed, experimental
1663 Thread idle threshold.
1665 Threads in excess of thread_pool_min, which have been idle for at least
1667 this long, will be destroyed.
1668 thread_pool_watchdog
1670 • Units: seconds
1671 • Default: 60.000
1673 • Minimum: 0.100
1675 • Flags: experimental
1677 Thread queue stuck watchdog.
1679 If no queued work have been released for this long, the worker process
1681 panics itself.
1682 thread_pools
1684 • Units: pools
1685 • Default: 2
1687 • Minimum: 1
1689 • Maximum: 32
1691 • Flags: delayed, experimental
1693 Number of worker thread pools.
1695 Increasing the number of worker pools decreases lock contention. Each
1697 worker pool also has a thread accepting new connections, so for very
1698 high rates of incoming new connections on systems with many cores, in‐
1699 creasing the worker pools may be required.
1700 Too many pools waste CPU and RAM resources, and more than one pool for
1702 each CPU is most likely detrimental to performance.
1703 Can be increased on the fly, but decreases require a restart to take
1705 effect, unless the drop_pools experimental debug flag is set.
1706 thread_queue_limit
1708 • Units: requests
1709 • Default: 20
1711 • Minimum: 0
1713 • Flags: experimental
1715 Permitted request queue length per thread-pool.
1717 This sets the number of requests we will queue, waiting for an avail‐
1719 able thread. Above this limit sessions will be dropped instead of
1720 queued.
1721 thread_stats_rate
1723 • Units: requests
1724 • Default: 10
1726 • Minimum: 0
1728 • Flags: experimental
1730 Worker threads accumulate statistics, and dump these into the global
1732 stats counters if the lock is free when they finish a job (re‐
1733 quest/fetch etc.) This parameters defines the maximum number of jobs a
1734 worker thread may handle, before it is forced to dump its accumulated
1735 stats into the global counters.
1736 timeout_idle
1738 • Units: seconds
1739 • Default: 5.000
1741 • Minimum: 0.000
1743 Idle timeout for client connections.
1745 A connection is considered idle until we have received the full request
1747 headers.
1748 This parameter is particularly relevant for HTTP1 keepalive connec‐
1750 tions which are closed unless the next request is received before this
1751 timeout is reached.
1752 timeout_linger
1754 • Units: seconds
1755 • Default: 0.050
1757 • Minimum: 0.000
1759 • Flags: experimental
1761 How long the worker thread lingers on an idle session before handing it
1763 over to the waiter. When sessions are reused, as much as half of all
1764 reuses happen within the first 100 msec of the previous request com‐
1765 pleting. Setting this too high results in worker threads not doing
1766 anything for their keep, setting it too low just means that more ses‐
1767 sions take a detour around the waiter.
1768 vary_notice
1770 • Units: variants
1771 • Default: 10
1773 • Minimum: 1
1775 How many variants need to be evaluated to log a Notice that there might
1777 be too many variants.
1778 vcc_allow_inline_c
1780 • Units: bool
1781 • Default: off
1783 Allow inline C code in VCL.
1785 vcc_err_unref
1787 • Units: bool
1788 • Default: on
1790 Unreferenced VCL objects result in error.
1792 vcc_unsafe_path
1794 • Units: bool
1795 • Default: on
1797 Allow '/' in vmod & include paths. Allow 'import ... from ...'.
1799 vcl_cooldown
1801 • Units: seconds
1802 • Default: 600.000
1804 • Minimum: 1.000
1806 How long a VCL is kept warm after being replaced as the active VCL
1808 (granularity approximately 30 seconds).
1809 vcl_path
1811 • Default: /opt/varnish/etc/varnish:/opt/varnish/share/varnish/vcl
1812 Directory (or colon separated list of directories) from which relative
1814 VCL filenames (vcl.load and include) are to be found. By default Var‐
1815 nish searches VCL files in both the system configuration and shared
1816 data directories to allow packages to drop their VCL files in a stan‐
1817 dard location where relative includes would work.
1818 vmod_path
1820 • Default: /opt/varnish/lib/varnish/vmods
1821 Directory (or colon separated list of directories) where VMODs are to
1823 be found.
1824 vsl_buffer
1826 • Units: bytes
1827 • Default: 16k
1829 • Minimum: vsl_reclen + 12 bytes
1831 Bytes of (req-/backend-)workspace dedicated to buffering VSL records.
1833 When this parameter is adjusted, most likely workspace_client and
1834 workspace_backend will have to be adjusted by the same amount.
1835 Setting this too high costs memory, setting it too low will cause more
1837 VSL flushes and likely increase lock-contention on the VSL mutex.
1838 vsl_mask
1840 • Default: -Debug,-ObjProtocol,-ObjStatus,-ObjReason,-Obj‐
1841 Header,-VCL_trace,-ExpKill,-WorkThread,-Hash,-VfpAcct,-H2Rx‐
1842 Hdr,-H2RxBody,-H2TxHdr,-H2TxBody,-VdpAcct
1843 Mask individual VSL messages from being logged.
1845 default
1847 Set default value
1848 Use +/- prefix in front of VSL tag name to unmask/mask individual VSL
1850 messages.
1851 vsl_reclen
1853 • Units: bytes
1854 • Default: 255b
1856 • Minimum: 16b
1858 • Maximum: vsl_buffer - 12 bytes
1860 Maximum number of bytes in SHM log record.
1862 vsl_space
1864 • Units: bytes
1865 • Default: 80M
1867 • Minimum: 1M
1869 • Maximum: 4G
1871 • Flags: must_restart
1873 The amount of space to allocate for the VSL fifo buffer in the VSM mem‐
1875 ory segment. If you make this too small, varnish{ncsa|log} etc will
1876 not be able to keep up. Making it too large just costs memory re‐
1877 sources.
1878 vsm_free_cooldown
1880 • Units: seconds
1881 • Default: 60.000
1883 • Minimum: 10.000
1885 • Maximum: 600.000
1887 How long VSM memory is kept warm after a deallocation (granularity ap‐
1889 proximately 2 seconds).
1890 vsm_space
1892 • Units: bytes
1893 • Default: 1M
1895 • Minimum: 1M
1897 • Maximum: 1G
1899 DEPRECATED: This parameter is ignored. There is no global limit on
1901 amount of shared memory now.
1902 workspace_backend
1904 • Units: bytes
1905 • Default: 96k
1907 • Minimum: 1k
1909 • Flags: delayed
1911 Bytes of HTTP protocol workspace for backend HTTP req/resp. If larger
1913 than 4k, use a multiple of 4k for VM efficiency.
1914 workspace_client
1916 • Units: bytes
1917 • Default: 96k
1919 • Minimum: 9k
1921 • Flags: delayed
1923 Bytes of HTTP protocol workspace for clients HTTP req/resp. Use a mul‐
1925 tiple of 4k for VM efficiency. For HTTP/2 compliance this must be at
1926 least 20k, in order to receive fullsize (=16k) frames from the client.
1927 That usually happens only in POST/PUT bodies. For other traffic-pat‐
1928 terns smaller values work just fine.
1929 workspace_session
1931 • Units: bytes
1932 • Default: 0.75k
1934 • Minimum: 384b
1936 • Flags: delayed
1938 Allocation size for session structure and workspace. The workspace
1940 is primarily used for TCP connection addresses. If larger than 4k, use
1941 a multiple of 4k for VM efficiency.
1942 workspace_thread
1944 • Units: bytes
1945 • Default: 2k
1947 • Minimum: 0.25k
1949 • Maximum: 8k
1951 • Flags: delayed
1953 Bytes of auxiliary workspace per thread. This workspace is used for
1955 certain temporary data structures during the operation of a worker
1956 thread. One use is for the IO-vectors used during delivery. Setting
1957 this parameter too low may increase the number of writev() syscalls,
1958 setting it too high just wastes space. ~0.1k + UIO_MAXIOV *
1959 sizeof(struct iovec) (typically = ~16k for 64bit) is considered the
1960 maximum sensible value under any known circumstances (excluding exotic
1961 vmod use).
1962
1964 Varnish and bundled tools will, in most cases, exit with one of the
1965 following codes
1966 • 0 OK
1968 • 1 Some error which could be system-dependent and/or transient
1970 • 2 Serious configuration / parameter error - retrying with the same
1972 configuration / parameters is most likely useless
1973 The varnishd master process may also OR its exit code
1975 • with 0x20 when the varnishd child process died,
1977 • with 0x40 when the varnishd child process was terminated by a signal
1979 and
1980 • with 0x80 when a core was dumped.
1982
1984 • varnishlog(1)
1985 • varnishhist(1)
1987 • varnishncsa(1)
1989 • varnishstat(1)
1991 • varnishtop(1)
1993 • varnish-cli(7)
1995 • vcl(7)
1997
1999 The varnishd daemon was developed by Poul-Henning Kamp in cooperation
2000 with Verdens Gang AS and Varnish Software.
2001 This manual page was written by Dag-Erling Smørgrav with updates by
2003 Stig Sandbeck Mathisen <ssm@debian.org>, Nils Goroll and others.
2004
2006 This document is licensed under the same licence as Varnish itself. See
2007 LICENCE for details.
2008 • Copyright (c) 2007-2015 Varnish Software AS
2010 VARNISHD(1)