varnishd - Online in the Cloud

PROGRAM:

NAME

varnishd - HTTP accelerator daemon

SYNOPSIS

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

DESCRIPTION

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

OPTIONS

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

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

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

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

-F Do not fork, run in the foreground.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

-V Display the version number and exit.

-W waiter
Specifies the waiter type to use.

Hash Algorithm Options
The following hash algorithms are available:

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

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

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

Storage Backend Options
The following storage types are available:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The commands available are documented in varnish(7).

RUN TIME PARAMETERS

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

· experimental

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

· delayed

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

· restart

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

· reload

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

· experimental

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

· wizard

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

· only_root

Only works if varnishd is running as root.

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

· workspace_client: 16k

· thread_pool_workspace: 16k

· http_resp_size: 8k

· http_req_size: 12k

· gzip_stack_buffer: 4k

· thread_pool_stack: 64k

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

accept_filter
· Units: bool

· Default: off

· Flags: must_restart

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

acceptor_sleep_decay
· Default: 0.9

· Minimum: 0

· Maximum: 1

· Flags: experimental

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

acceptor_sleep_incr
· Units: seconds

· Default: 0.000

· Minimum: 0.000

· Maximum: 1.000

· Flags: experimental

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

acceptor_sleep_max
· Units: seconds

· Default: 0.050

· Minimum: 0.000

· Maximum: 10.000

· Flags: experimental

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

auto_restart
· Units: bool

· Default: on

Automatically restart the child/worker process if it dies.

backend_idle_timeout
· Units: seconds

· Default: 60.000

· Minimum: 1.000

Timeout before we close unused backend connections.

ban_dups
· Units: bool

· Default: on

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

ban_lurker_age
· Units: seconds

· Default: 60.000

· Minimum: 0.000

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

ban_lurker_batch
· Default: 1000

· Minimum: 1

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

ban_lurker_sleep
· Units: seconds

· Default: 0.010

· Minimum: 0.000

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

between_bytes_timeout
· Units: seconds

· Default: 60.000

· Minimum: 0.000

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

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

· Flags: must_reload

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

cli_buffer
· Units: bytes

· Default: 8k

· Minimum: 4k

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

cli_limit
· Units: bytes

· Default: 48k

· Minimum: 128b

· Maximum: 99999999b

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

cli_timeout
· Units: seconds

· Default: 60.000

· Minimum: 0.000

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

clock_skew
· Units: seconds

· Default: 10

· Minimum: 0

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

connect_timeout
· Units: seconds

· Default: 3.500

· Minimum: 0.000

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

critbit_cooloff
· Units: seconds

· Default: 180.000

· Minimum: 60.000

· Maximum: 254.000

· Flags: wizard

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

debug
· Default: none

Enable/Disable various kinds of debugging.

none Disable all debugging

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

req_state
VSL Request state engine

workspace
VSL Workspace operations

waiter VSL Waiter internals

waitinglist
VSL Waitinglist events

syncvsl
Make VSL synchronous

hashedge
Edge cases in Hash

vclrel Rapid VCL release

lurker VSL Ban lurker

esi_chop
Chop ESI fetch to bits

flush_head
Flush after http1 head

vtc_mode
Varnishtest Mode

witness
Emit WITNESS lock records

vsm_keep
Keep the VSM file on restart

default_grace
· Units: seconds

· Default: 10.000

· Minimum: 0.000

· Flags: obj_sticky

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

default_keep
· Units: seconds

· Default: 0.000

· Minimum: 0.000

· Flags: obj_sticky

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

default_ttl
· Units: seconds

· Default: 120.000

· Minimum: 0.000

· Flags: obj_sticky

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

feature
· Default: none

Enable/Disable various minor features.

none Disable all features.

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

short_panic
Short panic message.

wait_silo
Wait for persistent silo.

no_coredump
No coredumps.

esi_ignore_https
Treat HTTPS as HTTP in ESI:includes

esi_disable_xml_check
Don't check of body looks like XML

esi_ignore_other_elements
Ignore non-esi XML-elements

esi_remove_bom
Remove UTF-8 BOM

fetch_chunksize
· Units: bytes

· Default: 16k

· Minimum: 4k

· Flags: experimental

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

fetch_maxchunksize
· Units: bytes

· Default: 0.25G

· Minimum: 64k

· Flags: experimental

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

first_byte_timeout
· Units: seconds

· Default: 60.000

· Minimum: 0.000

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

gzip_buffer
· Units: bytes

· Default: 32k

· Minimum: 2k

· Flags: experimental

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

gzip_level
· Default: 6

· Minimum: 0

· Maximum: 9

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

gzip_memlevel
· Default: 8

· Minimum: 1

· Maximum: 9

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

http_gzip_support
· Units: bool

· Default: on

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

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

http_max_hdr
· Units: header lines

· Default: 64

· Minimum: 32

· Maximum: 65535

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

http_range_support
· Units: bool

· Default: on

Enable support for HTTP Range headers.

http_req_hdr_len
· Units: bytes

· Default: 8k

· Minimum: 40b

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

http_req_size
· Units: bytes

· Default: 32k

· Minimum: 0.25k

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

http_resp_hdr_len
· Units: bytes

· Default: 8k

· Minimum: 40b

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

http_resp_size
· Units: bytes

· Default: 32k

· Minimum: 0.25k

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

idle_send_timeout
· Units: seconds

· Default: 60.000

· Minimum: 0.000

· Flags: delayed

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

listen_depth
· Units: connections

· Default: 1024

· Minimum: 0

· Flags: must_restart

Listen queue depth.

lru_interval
· Units: seconds

· Default: 2.000

· Minimum: 0.000

· Flags: experimental

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

max_esi_depth
· Units: levels

· Default: 5

· Minimum: 0

Maximum depth of esi:include processing.

max_restarts
· Units: restarts

· Default: 4

· Minimum: 0

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

max_retries
· Units: retries

· Default: 4

· Minimum: 0

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

nuke_limit
· Units: allocations

· Default: 50

· Minimum: 0

· Flags: experimental

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

pcre_match_limit
· Default: 10000

· Minimum: 1

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

(See: PCRE_EXTRA_MATCH_LIMIT in pcre docs.)

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

pcre_match_limit_recursion
· Default: 20

· Minimum: 1

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

(See: PCRE_EXTRA_MATCH_LIMIT_RECURSION in pcre docs.)

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

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

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

Testcase r01576 can be useful when tuning this parameter.

ping_interval
· Units: seconds

· Default: 3

· Minimum: 0

· Flags: must_restart

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

pipe_timeout
· Units: seconds

· Default: 60.000

· Minimum: 0.000

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

pool_req
· Default: 10,100,10

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

min_pool
minimum size of free pool.

max_pool
maximum size of free pool.

max_age
max age of free element.

pool_sess
· Default: 10,100,10

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

min_pool
minimum size of free pool.

max_pool
maximum size of free pool.

max_age
max age of free element.

pool_vbo
· Default: 10,100,10

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

min_pool
minimum size of free pool.

max_pool
maximum size of free pool.

max_age
max age of free element.

prefer_ipv6
· Units: bool

· Default: off

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

rush_exponent
· Units: requests per request

· Default: 3

· Minimum: 2

· Flags: experimental

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

send_timeout
· Units: seconds

· Default: 600.000

· Minimum: 0.000

· Flags: delayed

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

session_max
· Units: sessions

· Default: 100000

· Minimum: 1000

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

shm_reclen
· Units: bytes

· Default: 255b

· Minimum: 16b

· Maximum: 4084

Old name for vsl_reclen, use that instead.

shortlived
· Units: seconds

· Default: 10.000

· Minimum: 0.000

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

sigsegv_handler
· Units: bool

· Default: on

· Flags: must_restart

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

syslog_cli_traffic
· Units: bool

· Default: on

Log all CLI traffic to syslog(LOG_INFO).

tcp_keepalive_intvl
· Units: seconds

· Default: 75.000

· Minimum: 1.000

· Maximum: 100.000

· Flags: experimental

The number of seconds between TCP keep-alive probes.

tcp_keepalive_probes
· Units: probes

· Default: 9

· Minimum: 1

· Maximum: 100

· Flags: experimental

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

tcp_keepalive_time
· Units: seconds

· Default: 7200.000

· Minimum: 1.000

· Maximum: 7200.000

· Flags: experimental

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

thread_pool_add_delay
· Units: seconds

· Default: 0.000

· Minimum: 0.000

· Flags: experimental

Wait at least this long after creating a thread.

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

Setting this too high results in insuffient worker threads.

thread_pool_destroy_delay
· Units: seconds

· Default: 1.000

· Minimum: 0.010

· Flags: delayed, experimental

Wait this long after destroying a thread.

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

thread_pool_fail_delay
· Units: seconds

· Default: 0.200

· Minimum: 0.010

· Flags: experimental

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

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

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

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

thread_pool_max
· Units: threads

· Default: 5000

· Minimum: 100

· Flags: delayed

The maximum number of worker threads in each pool.

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

thread_pool_min
· Units: threads

· Default: 100

· Maximum: 5000

· Flags: delayed

The minimum number of worker threads in each pool.

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

Minimum is 10 threads.

thread_pool_stack
· Units: bytes

· Default: 48k

· Minimum: 16k

· Flags: experimental

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

thread_pool_timeout
· Units: seconds

· Default: 300.000

· Minimum: 10.000

· Flags: delayed, experimental

Thread idle threshold.

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

thread_pools
· Units: pools

· Default: 2

· Minimum: 1

· Flags: delayed, experimental

Number of worker thread pools.

Increasing number of worker pools decreases lock contention.

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

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

thread_queue_limit
· Default: 20

· Minimum: 0

· Flags: experimental

Permitted queue length per thread-pool.

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

thread_stats_rate
· Units: requests

· Default: 10

· Minimum: 0

· Flags: experimental

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

timeout_idle
· Units: seconds

· Default: 5.000

· Minimum: 0.000

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

timeout_linger
· Units: seconds

· Default: 0.050

· Minimum: 0.000

· Flags: experimental

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

vcc_allow_inline_c
· Units: bool

· Default: off

Allow inline C code in VCL.

vcc_err_unref
· Units: bool

· Default: on

Unreferenced VCL objects result in error.

vcc_unsafe_path
· Units: bool

· Default: on

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

vcl_cooldown
· Units: seconds

· Default: 600.000

· Minimum: 0.000

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

vcl_dir
· Default: /etc/varnish

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

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

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

vsl_buffer
· Units: bytes

· Default: 4k

· Minimum: 267

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

The minimum tracks the vsl_reclen parameter + 12 bytes.

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

Mask individual VSL messages from being logged.

default
Set default value

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

vsl_reclen
· Units: bytes

· Default: 255b

· Minimum: 16b

· Maximum: 4084b

Maximum number of bytes in SHM log record.

The maximum tracks the vsl_buffer parameter - 12 bytes.

vsl_space
· Units: bytes

· Default: 80M

· Minimum: 1M

· Flags: must_restart

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

vsm_space
· Units: bytes

· Default: 1M

· Minimum: 1M

· Flags: must_restart

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

workspace_backend
· Units: bytes

· Default: 64k

· Minimum: 1k

· Flags: delayed

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

workspace_client
· Units: bytes

· Default: 64k

· Minimum: 9k

· Flags: delayed

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

workspace_session
· Units: bytes

· Default: 0.50k

· Minimum: 0.25k

· Flags: delayed

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

workspace_thread
· Units: bytes

· Default: 2k

· Minimum: 0.25k

· Maximum: 8k

· Flags: delayed

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

EXIT CODES

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

· 0 OK

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

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

The varnishd master process may also OR its exit code

· with 0x20 when the varnishd child process died,

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

· with 0x80 when a core was dumped.

Use varnishd online using onworks.net services