VARNISHD(1)VARNISHD(1)NAMEvarnishd - HTTP accelerator daemon
SYNOPSISvarnishd [-a address[:port]] [-b host[:port]] [-d] [-F] [-f config]
[-g group] [-h type[,options]] [-i identity] [-l shmlogsize] [-n
name] [-P file] [-p param=value] [-s type[,options]] [-T
address[:port]] [-t ttl] [-u user] [-V] [-w min[,max[,timeout]]]
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][,address[:port][...]
Listen for client requests on the specified address and port.
The address can be a host name (“localhost”), an IPv4 dot‐
ted-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, the default HTTP port as listed in /etc/services
is used. Multiple listening addresses and ports can be speci‐
fied as a whitespace- or comma-separated list.
-b host[:port]
Use the specified host as backend server. If port is not speci‐
fied, 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 fore‐
ground with a CLI connection on stdin/stdout, and the child
process must be started explicitly with a CLI command. Termi‐
nating the parent process will also terminate the child.
-F 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 no configu‐
ration is supplied varnishd will not start the cache process.
-g group
Specifies the name of an unprivileged group to which the child
process should switch before it starts accepting connections.
This is a shortcut for specifying the group run-time parameter.
-h type[,options]
Specifies the hash algorithm. See Hash Algorithms for a list of
supported algorithms.
-i identity
Specify the identity of the varnish server. This can be
accessed using server.identity from VCL
-l shmlogsize
Specify size of shmlog file. Scaling suffixes like 'k', 'm' can
be used up to (e)tabytes. Default is 80 Megabytes. Specifying
less than 8 Megabytes is unwise.
-n name
Specify a name for this instance. Amonst 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 process's PID to the specified file.
-p param=value
Set the parameter specified by param to the specified value.
See Run-Time Parameters for a list of parameters. This option
can be used multiple times to specify multiple parameters.
-S file
Path to a file containing a secret used for authorizing access
to the management port.
-s [name=]type[,options]
Use the specified storage backend. See Storage Types for a list
of supported storage types. This option can be used multiple
times to specify multiple storage files. You can name the dif‐
ferent backends. Varnish will then reference that backend with
the given name in logs, statistics, etc.
-T address[:port]
Offer a management interface on the specified address and port.
See Management Interface for a list of management commands.
-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.
-t ttl Specifies a hard minimum time to live for cached documents.
This is a shortcut for specifying the default_ttl run-time
parameter.
-u user
Specifies the name of an unprivileged user to which the child
process should switch before it starts accepting connections.
This is a shortcut for specifying the user run- time parameter.
If specifying both a user and a group, the user should be speci‐
fied first.
-V Display the version number and exit.
-w min[,max[,timeout]]
Start at least min but no more than max worker threads with the
specified idle timeout. This is a shortcut for specifying the
thread_pool_min, thread_pool_max and thread_pool_timeout run-time
parameters.
If only one number is specified, thread_pool_min and thread_pool_max
are both set to this number, and thread_pool_timeout has no effect.
Hash Algorithms
The following hash algorithms are available:
simple_list
A simple doubly-linked list. Not recommended for production
use.
classic[,buckets]
A standard hash table. This is the default. 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.
critbit
A self-scaling tree structure. The default hash algorithm in
2.1. In comparison to a more traditional B tree the critbit tree
is almost completely lockless.
Storage Types
The following storage types are available:
malloc[,size]
Storage for each object is allocated with malloc(3).
The size parameter specifies the maximum amount of memory var‐
nishd will allocate. The size is assumed to be in bytes, unless
followed by one of the following suffixes:
K, k The size is expressed in kibibytes.
M, m The size is expressed in mebibytes.
G, g The size is expressed in gibibytes.
T, t The size is expressed in tebibytes.
The default size is unlimited.
file[,path[,size[,granularity]]]
Storage for each object is allocated from an arena backed by a
file. This is the default.
The path parameter specifies either the path to the backing file
or the path to a directory in which varnishd will create the
backing file. The default is /tmp.
The size parameter specifies the size of the backing file. The
size is assumed to be in bytes, unless fol‐ lowed by one of the
following suffixes:
K, k The size is expressed in kibibytes.
M, m The size is expressed in mebibytes.
G, g The size is expressed in gibibytes.
T, t The size is expressed in tebibytes.
% The size is expressed as a percentage of the free space
on the file system where it resides.
The default size is 50%.
If the backing file already exists, it will be truncated or
expanded to the specified size.
Note that if varnishd has to create or expand the file, it will
not pre-allocate the added space, leading to fragmentation,
which may adversely impact performance. Pre-creating the stor‐
age file using dd(1) will reduce fragmentation to a minimum.
The granularity parameter specifies the granularity of alloca‐
tion. All allocations are rounded up to this size. The size is
assumed to be in bytes, unless followed by one of the suffixes
described for size except for %.
The default size is the VM page size. The size should be
reduced if you have many small objects.
persistent,path,size {experimental}
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 path parameter specifies the path to the backing file. If the
file doesn't exist Varnish will create it.
The size parameter specifies the size of the backing file. The size
is assumed to be in bytes, unless followed by one of the following
suffixes:
K, k The size is expressed in kibibytes.
M, m The size is expressed in mebibytes.
G, g The size is expressed in gibibytes.
T, t The size is expressed in tebibytes.
Varnish will split the file into logical silos and write to the
silos in the manner of a circular buffer. Only one silo will be kept
open at any given point in time. Full silos are sealed. When Varnish
starts after a shutdown it will discard the content of any silo that
isn't sealed.
Transient Storage
If you name any of your storage backend "Transient" it will be used
for transient (short lived) objects. By default Varnish would use an
unlimited malloc backend for this.
Management Interface
If the -T option was specified, varnishd will offer a command-line man‐
agement 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
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.
Here is a list of all parameters, current as of last time we remembered
to update the manual page. This text is produced from the same text
you will find in the CLI if you use the param.show command, so should
there be a new parameter which is not listed here, you can find the
description using the CLI commands.
Be aware that on 32 bit systems, certain default values, such as
sess_workspace (=16k) and thread_pool_stack (=64k) are reduced relative
to the values listed here, in order to conserve VM space.
acceptor_sleep_decay
· Default: 0.900
· Flags: experimental
If we run out of resources, such as file descriptors or worker
threads, the acceptor will sleep between accepts. This parame‐
ter (multiplicatively) reduce the sleep duration for each suc‐
cesfull accept. (ie: 0.9 = reduce by 10%)
acceptor_sleep_incr
· Units: s
· Default: 0.001
· Flags: experimental
If we run out of resources, such as file descriptors or worker
threads, the acceptor will sleep between accepts. This parame‐
ter control how much longer we sleep, each time we fail to
accept a new connection.
acceptor_sleep_max
· Units: s
· Default: 0.050
· Flags: experimental
If we run out of resources, such as file descriptors or worker
threads, the acceptor will sleep between accepts. This parame‐
ter limits how long it can sleep between attempts to accept new
connections.
auto_restart
· Units: bool
· Default: on
Restart child process automatically if it dies.
ban_dups
· Units: bool
· Default: on
Detect and eliminate duplicate bans.
ban_lurker_sleep
· Units: s
· Default: 0.01
How long time does the ban lurker thread sleeps between success‐
ful attempts to push the last item up the ban list. It always
sleeps a second when nothing can be done. A value of zero dis‐
ables the ban lurker.
between_bytes_timeout
· Units: s
· Default: 60
Default timeout between bytes when receiving data from backend.
We only wait for this many seconds between bytes before giving
up. A value of 0 means it will never time out. VCL can override
this default value for each backend request and backend request.
This parameter does not apply to pipe.
cc_command
· Default: exec gcc -std=gnu99 -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: 8192
Size of buffer for CLI 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_timeout
· Units: seconds
· Default: 10
Timeout for the childs replies to CLI requests from the master.
clock_skew
· Units: s
· Default: 10
How much clockskew we are willing to accept between the backend
and our own clock.
connect_timeout
· Units: s
· Default: 0.7
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: s
· Default: 180.0
· Flags:
How long time the critbit hasher keeps deleted objheads on the
cooloff list.
default_grace
· Units: seconds
· Default: 10
· Flags: delayed
Default grace period. We will deliver an object this long after
it has expired, provided another thread is attempting to get a
new copy. Objects already cached will not be affected by
changes made until they are fetched from the backend again.
default_keep
· Units: seconds
· Default: 0
· Flags: delayed
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
The TTL assigned to objects if neither the backend nor the VCL
code assigns one. Objects already cached will not be affected
by changes made until they are fetched from the backend again.
To force an immediate effect at the expense of a total flush of
the cache use "ban.url ."
diag_bitmap
· Units: bitmap
· Default: 0
Bitmap controlling diagnostics code:
0x00000001 - CNT_Session states.
0x00000002 - workspace debugging.
0x00000004 - kqueue debugging.
0x00000008 - mutex logging.
0x00000010 - mutex contests.
0x00000020 - waiting list.
0x00000040 - object workspace.
0x00001000 - do not core-dump child process.
0x00002000 - only short panic message.
0x00004000 - panic to stderr.
0x00010000 - synchronize shmlog.
0x00020000 - synchronous start of persistence.
0x00040000 - release VCL early.
0x80000000 - do edge-detection on digest.
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esi_syntax
· Units: bitmap
· Default: 0
Bitmap controlling ESI parsing code:
0x00000001 - Don't check if it looks like XML
0x00000002 - Ignore non-esi elements
0x00000004 - Emit parsing debug records
0x00000008 - Force-split parser input (debugging)
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expiry_sleep
· Units: seconds
· Default: 1
How long the expiry thread sleeps when there is nothing for it
to do.
fetch_chunksize
· Units: kilobytes
· Default: 128
· 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: kilobytes
· Default: 262144
· Flags: experimental
The maximum chunksize we attempt to allocate from storage. Mak‐
ing this too large may cause delays and storage fragmentation.
first_byte_timeout
· Units: s
· Default: 60
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 parame‐
ter does not apply to pipe.
group
· Default: magic
· Flags: must_restart
The unprivileged group to run as.
gzip_level
· Default: 6
Gzip compression level: 0=debug, 1=fast, 9=best
gzip_memlevel
· Default: 8
Gzip memory level 1=slow/least, 9=fast/most compression. Memory
impact is 1=1k, 2=2k, ... 9=256k.
gzip_stack_buffer
· Units: Bytes
· Default: 32768
· Flags: experimental
Size of stack buffer used for gzip processing. The stack buf‐
fers 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 prob‐
ably just a waste of memory.
gzip_tmp_space
· Default: 0
· Flags: experimental
Where temporary space for gzip/gunzip is allocated:
0 - malloc
1 - session workspace
2 - thread workspace
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If you have much gzip/gunzip activity, it may be an advantage to
use workspace for these allocations to reduce malloc activity.
Be aware that gzip needs 256+KB and gunzip needs 32+KB of
workspace (64+KB if ESI processing).
gzip_window
· Default: 15
Gzip window size 8=least, 15=most compression. Memory impact is
8=1k, 9=2k, ... 15=128k.
http_gzip_support
· Units: bool
· Default: on
· Flags: experimental
Enable gzip support. When enabled Varnish will compress uncom‐
pressed objects before they are stored in the cache. If a client
does not support gzip encoding Varnish will uncompress com‐
pressed objects on demand. Varnish will also rewrite the
Accept-Encoding header of clients indicating support for gzip
to:
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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
Maximum number of HTTP headers we will deal with in client
request or backend reponses. Note that the first line occupies
five header fields. This paramter does not influence storage
consumption, objects allocate exact space for the headers they
store.
http_range_support
· Units: bool
· Default: on
· Flags: experimental
Enable support for HTTP Range headers.
http_req_hdr_len
· Units: bytes
· Default: 4096
Maximum length of any HTTP client request header we will allow.
The limit is inclusive its continuation lines.
http_req_size
· Units: bytes
· Default: 32768
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 session workspace (param: sess_workspace) and
this parameter limits how much of that the request is allowed to
take up.
http_resp_hdr_len
· Units: bytes
· Default: 4096
Maximum length of any HTTP backend response header we will
allow. The limit is inclusive its continuation lines.
http_resp_size
· Units: bytes
· Default: 32768
Maximum number of bytes of HTTP backend resonse 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 worker workspace (param: sess_workspace) and
this parameter limits how much of that the request is allowed to
take up.
listen_address
· Default: :80
· Flags: must_restart
Whitespace separated list of network endpoints where Varnish
will accept requests. Possible formats: host, host:port, :port
listen_depth
· Units: connections
· Default: 1024
· Flags: must_restart
Listen queue depth.
log_hashstring
· Units: bool
· Default: on
Log the hash string components to shared memory log.
log_local_address
· Units: bool
· Default: off
Log the local address on the TCP connection in the SessionOpen
shared memory record.
lru_interval
· Units: seconds
· Default: 2
· 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
Maximum depth of esi:include processing.
max_restarts
· Units: restarts
· Default: 4
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.
nuke_limit
· Units: allocations
· Default: 10
· Flags: experimental
Maximum number of objects we attempt to nuke in orderto make
space for a object body.
ping_interval
· Units: seconds
· Default: 3
· 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
Idle timeout for PIPE sessions. If nothing have been received in
either direction for this many seconds, the session is closed.
prefer_ipv6
· Units: bool
· Default: off
Prefer IPv6 address when connecting to backends which have both
IPv4 and IPv6 addresses.
queue_max
· Units: %
· Default: 100
· Flags: experimental
Percentage permitted queue length.
This sets the ratio of queued requests to worker threads, above
which sessions will be dropped instead of queued.
rush_exponent
· Units: requests per request
· Default: 3
· 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.
saintmode_threshold
· Units: objects
· Default: 10
· Flags: experimental
The maximum number of objects held off by saint mode before no
further will be made to the backend until one times out. A
value of 0 disables saintmode.
send_timeout
· Units: seconds
· Default: 60
· 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.
sess_timeout
· Units: seconds
· Default: 5
Idle timeout for persistent sessions. If a HTTP request has not
been received in this many seconds, the session is closed.
sess_workspace
· Units: bytes
· Default: 65536
· Flags: delayed
Bytes of HTTP protocol workspace allocated for sessions. This
space must be big enough for the entire HTTP protocol header and
any edits done to it in the VCL code. Minimum is 1024 bytes.
session_linger
· Units: ms
· Default: 50
· Flags: experimental
How long time the workerthread lingers on the session to see if
a new request appears right away. If 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.
session_max
· Units: sessions
· Default: 100000
Maximum number of sessions we will allocate 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: 255
Maximum number of bytes in SHM log record. Maximum is 65535
bytes.
shm_workspace
· Units: bytes
· Default: 8192
· Flags: delayed
Bytes of shmlog workspace allocated for worker threads. If too
big, it wastes some ram, if too small it causes needless flushes
of the SHM workspace. These flushes show up in stats as "SHM
flushes due to overflow". Minimum is 4096 bytes.
shortlived
· Units: s
· Default: 10.0
Objects created with TTL shorter than this are always put in
transient storage.
syslog_cli_traffic
· Units: bool
· Default: on
Log all CLI traffic to syslog(LOG_INFO).
thread_pool_add_delay
· Units: milliseconds
· Default: 2
Wait at least this long between creating threads.
Setting this too long results in insuffient worker threads.
Setting this too short increases the risk of worker thread
pile-up.
thread_pool_add_threshold
· Units: requests
· Default: 2
· Flags: experimental
Overflow threshold for worker thread creation.
Setting this too low, will result in excess worker threads,
which is generally a bad idea.
Setting it too high results in insuffient worker threads.
thread_pool_fail_delay
· Units: milliseconds
· Default: 200
· 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 RAM resources for
thread stacks. This delay tries to not rush it 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: 500
· Flags: delayed, experimental
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: 5
· Flags: delayed, experimental
The minimum number of worker threads in each pool.
Increasing this may help ramp up faster from low load situations
where threads have expired.
Minimum is 2 threads.
thread_pool_purge_delay
· Units: milliseconds
· Default: 1000
· Flags: delayed, experimental
Wait this long between purging threads.
This controls the decay of thread pools when idle(-ish).
Minimum is 100 milliseconds.
thread_pool_stack
· Units: bytes
· Default: -1
· Flags: experimental
Worker thread stack size. On 32bit systems you may need to
tweak this down to fit many threads into the limited address
space.
thread_pool_timeout
· Units: seconds
· Default: 300
· Flags: delayed, experimental
Thread idle threshold.
Threads in excess of thread_pool_min, which have been idle for
at least this long are candidates for purging.
Minimum is 1 second.
thread_pool_workspace
· Units: bytes
· Default: 65536
· Flags: delayed
Bytes of HTTP protocol workspace allocated for worker threads.
This space must be big enough for the backend request and
responses, and response to the client plus any other memory
needs in the VCL code.Minimum is 1024 bytes.
thread_pools
· Units: pools
· Default: 2
· 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_stats_rate
· Units: requests
· Default: 10
· Flags: experimental
Worker threads accumulate statistics, and dump these into the
global stats counters if the lock is free when they finish a
request. This parameters defines the maximum number of requests
a worker thread may handle, before it is forced to dump its
accumulated stats into the global counters.
user
· Default: magic
· Flags: must_restart
The unprivileged user to run as. Setting this will also set
"group" to the specified user's primary group.
vcc_err_unref
· Units: bool
· Default: on
Unreferenced VCL objects result in error.
vcl_dir
· Default: /usr/local/etc/varnish
Directory from which relative VCL filenames (vcl.load and
include) are opened.
vcl_trace
· Units: bool
· Default: off
Trace VCL execution in the shmlog. Enabling this will allow you
to see the path each request has taken through the VCL program.
This generates a lot of logrecords so it is off by default.
vmod_dir
· Default: /usr/local/lib/varnish/vmods
Directory where VCL modules are to be found.
waiter
· Default: default
· Flags: must_restart, experimental
Select the waiter kernel interface.
SEE ALSO
· varnish-cli(7)
· varnishlog(1)
· varnishhist(1)
· varnishncsa(1)
· varnishstat(1)
· varnishtop(1)
· vcl(7)HISTORY
The varnishd daemon was developed by Poul-Henning Kamp in cooperation
with Verdens Gang AS, Varnish Software AS and Varnish Software.
This manual page was written by Dag-Erling Smørgrav with updates by
Stig Sandbeck Mathisen ⟨ssm@debian.org⟩
COPYRIGHT
This document is licensed under the same licence as Varnish itself. See
LICENCE for details.
· Copyright (c) 2007-2011 Varnish Software AS
AUTHOR
Dag-Erling Smørgrav, Stig Sandbeck Mathisen, Per Buer
1.0 2010-05-31 VARNISHD(1)
