doc/sphinx/reference/vcl_var.rst
.. Copyright (c) 2018-2021 Varnish Software AS SPDX-License-Identifier: BSD-2-Clause See LICENSE file for full text of license
.. NOTE: please maintain lexicographic order of foo.* variable names
.. _vcl_variables:
These variables describe the network connection between the client and varnishd.
Without PROXY protocol::
client server
remote local
v v
CLIENT ------------ VARNISHD
With PROXY protocol::
client server remote local
v v v v
CLIENT ------------ PROXY ------------ VARNISHD
.. _client.identity:
client.identity
Type: STRING
Readable from: client, backend
Writable from: client
Identification of the client, used to load balance
in the client director. Defaults to ``client.ip``
This variable can be overwritten with more precise
information, for instance extracted from a ``Cookie:``
header.
.. _client.ip:
client.ip
Type: IP
Readable from: client, backend
The client's IP address, either the same as ``remote.ip``
or what the PROXY protocol told us.
.. _server.hostname:
server.hostname
Type: STRING
Readable from: all
The host name of the server, as returned by the
`gethostname(3)` system function.
.. _server.identity:
server.identity
Type: STRING
Readable from: all
The identity of the server, as set by the ``-i`` parameter.
If an ``-i`` parameter is not passed to varnishd, the return
value from `gethostname(3)` system function will be used.
.. _server.ip:
server.ip
Type: IP
Readable from: client, backend
The IP address of the socket on which the client
connection was received, either the same as ``local.ip``
or what the PROXY protocol told us.
.. _remote.ip:
remote.ip
Type: IP
Readable from: client, backend
The IP address of the other end of the TCP connection.
This can either be the clients IP, or the outgoing IP
of a proxy server.
If the connection is a UNIX domain socket, the value
will be ``0.0.0.0:0``
.. _local.endpoint:
local.endpoint VCL >= 4.1
Type: STRING
Readable from: client, backend
The address of the '-a' socket the session was accepted on.
If the argument was ``-a foo=:81`` this would be ":81"
.. _local.ip:
local.ip
Type: IP
Readable from: client, backend
The IP address (and port number) of the local end of the
TCP connection, for instance ``192.168.1.1:81``
If the connection is a UNIX domain socket, the value
will be ``0.0.0.0:0``
.. _local.socket:
local.socket VCL >= 4.1
Type: STRING
Readable from: client, backend
The name of the '-a' socket the session was accepted on.
If the argument was ``-a foo=:81`` this would be "foo".
Note that all '-a' gets a default name on the form ``a%d``
if no name is provided.
These variables describe the present request, and when ESI:include requests are being processed, req_top points to the request received from the client.
.. _req:
req
Type: HTTP
Readable from: client
The entire request HTTP data structure.
Mostly useful for passing to VMODs.
.. _req.backend_hint:
req.backend_hint
Type: BACKEND
Readable from: client
Writable from: client
Set bereq.backend to this if we attempt to fetch.
When set to a director, reading this variable returns
an actual backend if the director has resolved immediately,
or the director otherwise.
When used in string context, returns the name of the director
or backend, respectively.
.. _req.can_gzip:
req.can_gzip
Type: BOOL
Readable from: client
True if the client provided ``gzip`` or ``x-gzip`` in the
``Accept-Encoding`` header.
req.esi VCL <= 4.0
Type: BOOL
Readable from: client
Writable from: client
Set to ``false`` to disable ESI processing
regardless of any value in beresp.do_esi. Defaults
to ``true``. This variable is replaced by ``resp.do_esi``
in VCL 4.1.
.. _req.esi_level:
req.esi_level
Type: INT
Readable from: client
A count of how many levels of ESI requests we're currently at.
.. _req.filters:
req.filters
Type: STRING
Readable from: vcl_recv
Writable from: vcl_recv
List of Varnish Fetch Processor (VFP) filters the req.body
will be pulled through. The order left to right signifies
processing from client to cache, iow the leftmost filter is
run first on the body as received from the client after
decoding of any transfer encodings.
VFP Filters change the body before potentially being cached
(e.g. using ``std.cache_req.body()``) and/or being handled by
the backend side, where it may get processed again by
bereq.filters.
Trying to set req.filters after processing the request body
(again, for example with ``std.cache_req.body()``) triggers a
VCL error.
.. _req.grace:
req.grace
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Upper limit on the object grace.
During lookup the minimum of req.grace and the object's stored
grace value will be used as the object's grace.
When reading the unset value, it is returned as -1.
.. _req.hash:
req.hash
Type: BLOB
Readable from: vcl_hit, vcl_miss, vcl_pass, vcl_purge, vcl_deliver, vcl_synth, vcl_pipe
The hash key of this request.
Mostly useful for passing to VMODs, but can also be useful
for debugging hit/miss status.
.. _req.hash_always_miss:
req.hash_always_miss
Type: BOOL
Readable from: client
Writable from: client
Default: ``false``.
Force a cache miss for this request, even if perfectly
good matching objects are in the cache.
This is useful to force-update the cache without invalidating
existing entries in case the fetch fails.
.. _req.hash_ignore_busy:
req.hash_ignore_busy
Type: BOOL
Readable from: client
Writable from: client
Default: ``false``.
Ignore any busy object during cache lookup.
You only want to do this when you have two server looking
up content sideways from each other to avoid deadlocks.
.. _req.hash_ignore_vary:
req.hash_ignore_vary
Type: BOOL
Readable from: client
Writable from: client
Default: ``false``.
Ignore objects vary headers during cache lookup.
This returns the very first match regardless of the object
compatibility with the client request. This is useful when
variants are irrelevant to certain clients, and differences
in the way the resource is presented don't change how the
client will interpret it.
Use with caution.
.. _req.http:
req.http.*
Type: HEADER
Readable from: client
Writable from: client
Unsettable from: client
The headers of request, things like ``req.http.date``.
The RFCs allow multiple headers with the same name, and both
``set`` and ``unset`` will remove *all* headers with the name
given.
The header name ``*`` is a VCL symbol and as such cannot, for
example, start with a numeral. To work with valid header that
can't be represented as VCL symbols it is possible to quote the
name, like ``req.http."grammatically.valid"``. None of the HTTP
headers present in IANA registries need to be quoted, so the
quoted syntax is discouraged but available for interoperability.
Some headers that cannot be tampered with for proper HTTP fetch
or delivery are read-only.
req.http.content-length
Type: HEADER
Readable from: client
The content-length header field is protected, see protected_headers_.
req.http.transfer-encoding
Type: HEADER
Readable from: client
The transfer-encoding header field is protected, see protected_headers_.
.. _req.is_hitmiss:
req.is_hitmiss
Type: BOOL
Readable from: vcl_miss, vcl_deliver, vcl_pass, vcl_synth
If this request resulted in a hitmiss
.. _req.is_hitpass:
req.is_hitpass
Type: BOOL
Readable from: vcl_pass, vcl_deliver, vcl_synth
If this request resulted in a hitpass
.. _req.method:
req.method
Type: STRING
Readable from: client
Writable from: client
The request method (e.g. "GET", "HEAD", ...)
req.proto VCL <= 4.0
Type: STRING
Readable from: client
Writable from: client
The HTTP protocol version used by the client, usually "HTTP/1.1"
or "HTTP/2.0".
.. _req.proto:
req.proto VCL >= 4.1
Type: STRING
Readable from: client
The HTTP protocol version used by the client, usually "HTTP/1.1"
or "HTTP/2.0".
.. _req.restarts:
req.restarts
Type: INT
Readable from: client
A count of how many times this request has been restarted.
.. _req.storage:
req.storage
Type: STEVEDORE
Readable from: client
Writable from: client
The storage backend to use to save this request body.
.. _req.time:
req.time
Type: TIME
Readable from: client
The time when the request was fully received, remains constant
across restarts.
.. _req.trace:
req.trace
Type: BOOL
Readable from: client
Writable from: client
Controls if ``VCL_trace`` VSL records are emitted for the current
request, see :ref:`vsl(7)`.
Defaults to the setting of the ``feature trace`` parameter,
see :ref:`varnishd(1)`. Does not get reset by a rollback.
.. _req.transport:
req.transport
Type: STRING
Readable from: client
The transport protocol which brought this request.
.. _req.max_age:
req.max_age
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Upper limit on the object age for cache lookups to return hit. Matches
``Cache-Control: max-age`` request header semantics.
When reading the unset value, it is returned as -1.
.. _req.ttl:
req.ttl
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Deprecated alias of ``req.max-age``, which will be removed in a future
version of Vinyl-Cache.
.. _req.url:
req.url
Type: STRING
Readable from: client
Writable from: client
The requested URL, for instance "/robots.txt".
.. _req.xid:
req.xid
Type: INT
Readable from: client
Unique ID of this request.
.. _req_top.http:
req_top.http.*
Type: HEADER
Readable from: client
HTTP headers of the top-level request in a tree of ESI requests.
Identical to req.http. in non-ESI requests.
See req.http_ for general notes.
.. _req_top.method:
req_top.method
Type: STRING
Readable from: client
The request method of the top-level request in a tree
of ESI requests. (e.g. "GET", "HEAD").
Identical to req.method in non-ESI requests.
.. _req_top.proto:
req_top.proto
Type: STRING
Readable from: client
HTTP protocol version of the top-level request in a tree of
ESI requests.
Identical to req.proto in non-ESI requests.
.. _req_top.time:
req_top.time
Type: TIME
Readable from: client
The time when the top-level request was fully received,
remains constant across restarts.
.. _req_top.url:
req_top.url
Type: STRING
Readable from: client
The requested URL of the top-level request in a tree
of ESI requests.
Identical to req.url in non-ESI requests.
This is the request we send to the backend, it is built from the
clients req.* fields by filtering out "per-hop" fields which
should not be passed along (Connection:, Range: and similar).
Slightly more fields are allowed through for pass` fetches than for `miss` fetches, for instance Range``.
bereq
Type: HTTP
Readable from: backend
The entire backend request HTTP data structure.
Mostly useful as argument to VMODs.
.. _bereq.backend:
bereq.backend
Type: BACKEND
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
This is the backend or director we attempt to fetch from.
When set to a director, reading this variable returns
an actual backend if the director has resolved immediately,
or the director otherwise.
When used in string context, returns the name of the director
or backend, respectively.
.. _bereq.between_bytes_timeout:
bereq.between_bytes_timeout
Type: DURATION
Readable from: backend
Writable from: backend
Unsettable from: vcl_pipe, backend
Default: ``.between_bytes_timeout`` attribute from the
:ref:`backend_definition`, which defaults to the
``between_bytes_timeout`` parameter, see :ref:`varnishd(1)`.
The time in seconds to wait between each received byte from the
backend. Not available in pipe mode.
.. _bereq.body:
bereq.body
Type: BODY
Unsettable from: vcl_backend_fetch
The request body.
Unset will also remove bereq.http.content-length_.
.. _bereq.connect_timeout:
bereq.connect_timeout
Type: DURATION
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
Unsettable from: vcl_pipe, backend
Default: ``.connect_timeout`` attribute from the
:ref:`backend_definition`, which defaults to the
``connect_timeout`` parameter, see :ref:`varnishd(1)`.
The time in seconds to wait for a backend connection to be
established.
.. _bereq.filters:
bereq.filters
Type: STRING
Readable from: vcl_backend_fetch
Writable from: vcl_backend_fetch
List of VDP filters the bereq.body will be pushed through when
sending the body to the backend.
.. _bereq.first_byte_timeout:
bereq.first_byte_timeout
Type: DURATION
Readable from: backend
Writable from: backend
Unsettable from: vcl_pipe, backend
Default: ``.first_byte_timeout`` attribute from the
:ref:`backend_definition`, which defaults to the
``first_byte_timeout`` parameter, see :ref:`varnishd(1)`.
The time in seconds to wait getting the first byte back
from the backend. Not available in pipe mode.
.. _bereq.hash:
bereq.hash
Type: BLOB
Readable from: vcl_pipe, backend
The hash key of this request, a copy of ``req.hash``.
.. _bereq.http:
bereq.http.*
Type: HEADER
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
Unsettable from: vcl_pipe, backend
The headers to be sent to the backend.
See req.http_ for general notes.
.. _bereq.http.content-length:
bereq.http.content-length
Type: HEADER
Readable from: backend
The content-length header field is protected, see protected_headers_.
bereq.http.transfer-encoding
Type: HEADER
Readable from: backend
The transfer-encoding header field is protected, see protected_headers_.
.. _bereq.is_bgfetch:
bereq.is_bgfetch
Type: BOOL
Readable from: backend
True for fetches where the client got a hit on an object in
grace, and this fetch was kicked of in the background to get
a fresh copy.
.. _bereq.is_hitmiss:
bereq.is_hitmiss
Type: BOOL
Readable from: backend
If this backend request was caused by a hitmiss.
.. _bereq.is_hitpass:
bereq.is_hitpass
Type: BOOL
Readable from: backend
If this backend request was caused by a hitpass.
.. _bereq.method:
bereq.method
Type: STRING
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
The request type (e.g. "GET", "HEAD").
Regular (non-pipe, non-pass) fetches are always "GET"
bereq.proto VCL <= 4.0
Type: STRING
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
The HTTP protocol version, "HTTP/1.1" unless a pass or pipe
request has "HTTP/1.0" in ``req.proto``
.. _bereq.proto:
bereq.proto VCL >= 4.1
Type: STRING
Readable from: vcl_pipe, backend
The HTTP protocol version, "HTTP/1.1" unless a pass or pipe
request has "HTTP/1.0" in ``req.proto``
.. _bereq.retries:
bereq.retries
Type: INT
Readable from: backend
A count of how many times this request has been retried.
.. _bereq.retry_connect:
bereq.retry_connect
Type: BOOL
Readable from: backend
Writable from: backend
Default: ``true``.
Controls whether Varnish will make a second attempt to connect to the
backend if a first connection reuse attempt failed. Setting to ``false``
means that no retries will be made. However, setting this to ``true``
does not guarantee that a retry will always be attempted, as there are
other factors involved in the decision (ex: a request body not being
cached).
Note that this only controls automatic retries due to connection
failures, and does not affect retries initiated from VCL using
``return(retry);``.
.. _bereq.task_deadline:
bereq.task_deadline
Type: DURATION
Readable from: vcl_pipe
Writable from: vcl_pipe
Unsettable from: vcl_pipe
Deadline for pipe sessions, defaults ``0s``, which falls back to the
``pipe_task_deadline`` parameter, see :ref:`varnishd(1)`
.. _bereq.time:
bereq.time
Type: TIME
Readable from: vcl_pipe, backend
The time when we started preparing the first backend request,
remains constant across retries.
.. _bereq.trace:
bereq.trace
Type: BOOL
Readable from: backend
Writable from: backend
Controls if ``VCL_trace`` VSL records are emitted for the current
request, see :ref:`vsl(7)`.
Inherits the value of ``req.trace`` when the backend request
is created. Does not get reset by a rollback.
.. _bereq.uncacheable:
bereq.uncacheable
Type: BOOL
Readable from: backend
Indicates whether this request is uncacheable due to a
`pass` in the client side or a hit on an hit-for-pass object.
.. _bereq.url:
bereq.url
Type: STRING
Readable from: vcl_pipe, backend
Writable from: vcl_pipe, backend
The requested URL, copied from ``req.url``
.. _bereq.xid:
bereq.xid
Type: INT
Readable from: vcl_pipe, backend
Unique ID of this request.
The response received from the backend, one cache misses, the
store object is built from beresp.
beresp
Type: HTTP
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The entire backend response HTTP data structure, useful as
argument to VMOD functions.
.. _beresp.age:
beresp.age
Type: DURATION
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: Age header, or zero.
The age of the object.
.. _beresp.backend:
beresp.backend
Type: BACKEND
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
This is the backend we fetched from. If bereq.backend
was set to a director, this will be the backend selected
by the director.
When used in string context, returns its name.
beresp.backend.ip VCL <= 4.0
Type: IP
Readable from: vcl_backend_response
IP of the backend this response was fetched from.
.. _beresp.backend.name:
beresp.backend.name
Type: STRING
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Name of the backend this response was fetched from.
Same as beresp.backend.
.. _beresp.body:
beresp.body
Type: BODY
Writable from: vcl_backend_error
For producing a synthetic body.
.. _beresp.do_esi:
beresp.do_esi
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: ``false``.
Set it to true to parse the object for ESI directives. This is
necessary for later ESI processing on the client side. If
beresp.do_esi is false when an object enters the cache, client
side ESI processing will not be possible (obj.can_esi will be
false).
It is a VCL error to use beresp.do_esi after setting beresp.filters.
.. _beresp.do_gunzip:
beresp.do_gunzip
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: ``false``.
Set to ``true`` to gunzip the object while storing it in the
cache.
If ``http_gzip_support`` is disabled, setting this variable
has no effect.
It is a VCL error to use beresp.do_gunzip after setting beresp.filters.
.. _beresp.do_gzip:
beresp.do_gzip
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: ``false``.
Set to ``true`` to gzip the object while storing it.
If ``http_gzip_support`` is disabled, setting this variable
has no effect.
It is a VCL error to use beresp.do_gzip after setting beresp.filters.
.. _beresp.do_stream:
beresp.do_stream
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: ``true``.
Deliver the object to the client while fetching the whole
object into varnish.
For uncacheable objects, storage for parts of the body which
have been sent to the client may get freed early, depending
on the storage engine used.
This variable has no effect if beresp.do_esi is true or when
the response body is empty.
.. _beresp.filters:
beresp.filters
Type: STRING
Readable from: vcl_backend_response
Writable from: vcl_backend_response
List of Varnish Fetch Processor (VFP) filters the beresp.body
will be pulled through. The order left to right signifies
processing from backend to cache, iow the leftmost filter is
run first on the body as received from the backend after
decoding of any transfer encodings.
VFP Filters change the body before going into the cache and/or
being handed to the client side, where it may get processed
again by resp.filters.
The following VFP filters exist in varnish-cache:
* ``gzip``: compress a body using gzip
* ``testgunzip``: Test if a body is valid gzip and refuse it
otherwise
* ``gunzip``: Uncompress gzip content
* ``esi``: ESI-process plain text content
* ``esi_gzip``: Save gzipped snippets for efficient
ESI-processing
This filter enables stitching together ESI from individually
gzipped fragments, saving processing power for
re-compression on the client side at the expense of some
compression efficiency.
Additional VFP filters are available from VMODs.
By default, beresp.filters is constructed as follows:
* ``gunzip`` gets added for gzipped content if
``beresp.do_gunzip`` or ``beresp.do_esi`` are true.
* ``esi_gzip`` gets added if ``beresp.do_esi`` is true
together with ``beresp.do_gzip`` or content is already
compressed.
* ``esi`` gets added if ``beresp.do_esi`` is true
* ``gzip`` gets added for uncompressed content if
``beresp.do_gzip`` is true
* ``testgunzip`` gets added for compressed content if
``beresp.do_gunzip`` is false.
After beresp.filters is set, using any of the beforementioned
``beresp.do_*`` switches is a VCL error.
.. _beresp.grace:
beresp.grace
Type: DURATION
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: Cache-Control ``stale-while-revalidate`` directive,
or ``default_grace`` parameter.
Set to a period to enable grace.
.. _beresp.http:
beresp.http.*
Type: HEADER
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Unsettable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The HTTP headers returned from the server.
See req.http_ for general notes.
beresp.http.content-length
Type: HEADER
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The content-length header field is protected, see protected_headers_.
beresp.http.transfer-encoding
Type: HEADER
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The transfer-encoding header field is protected, see protected_headers_.
.. _beresp.keep:
beresp.keep
Type: DURATION
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: ``default_keep`` parameter.
Set to a period to enable conditional backend requests.
The keep time is cache lifetime in addition to the ttl.
Objects with ttl expired but with keep time left may be used
to issue conditional (If-Modified-Since / If-None-Match)
requests to the backend to refresh them.
beresp.proto VCL <= 4.0
Type: STRING
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The HTTP protocol version the backend replied with.
.. _beresp.proto:
beresp.proto VCL >= 4.1
Type: STRING
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The HTTP protocol version the backend replied with.
.. _beresp.reason:
beresp.reason
Type: STRING
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The HTTP status message returned by the server.
.. _beresp.status:
beresp.status
Type: INT
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The HTTP status code returned by the server.
More information in the `HTTP response status`_ section.
.. _beresp.storage:
beresp.storage
Type: STEVEDORE
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
The storage backend to use to save this object. If
none is set, Varnish will pick a storage backend in a
round-robin fashion, or the `Transient` backend if
the object is short-lived.
beresp.storage_hint VCL <= 4.0
Type: STRING
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Deprecated since varnish 5.1 and discontinued since VCL
4.1 (varnish 6.0). Use beresp.storage instead.
Hint to Varnish that you want to save this object to a
particular storage backend.
.. _beresp.time:
beresp.time
Type: TIME
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
When the backend headers were fully received just before
``vcl_backend_response {}`` was entered, or when
``vcl_backend_error {}`` was entered.
.. _beresp.transit_buffer:
beresp.transit_buffer
Type: BYTES
Readable from: vcl_backend_response
Writable from: vcl_backend_response
Default: ``transit_buffer`` parameter, see :ref:`varnishd(1)`.
The maximum number of bytes the client can be ahead of the
backend during a streaming pass if ``beresp`` is
uncacheable. See also ``transit_buffer`` parameter
documentation in :ref:`varnishd(1)`.
.. _beresp.ttl:
beresp.ttl
Type: DURATION
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Default: Cache-Control ``s-maxage`` or ``max-age`` directives,
or a value computed from the Expires header's deadline, or the
``default_ttl`` parameter.
The object's remaining time to live, in seconds.
.. _beresp.uncacheable:
beresp.uncacheable
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Writable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
Inherited from bereq.uncacheable, see there.
Setting this variable makes the object uncacheable.
This may produce a hit-for-miss object in the cache.
Clearing the variable has no effect and will log the warning
"Ignoring attempt to reset beresp.uncacheable".
.. _beresp.was_304:
beresp.was_304
Type: BOOL
Readable from: vcl_backend_response, vcl_backend_error, vcl_backend_refresh
When ``true`` this indicates that we got a 304 response
to our conditional fetch from the backend and turned
that into ``beresp.status = 200``
This is the stale object we had in cache. It cannot be modified.
.. _obj_stale.age:
obj_stale.age
Type: DURATION
Readable from: vcl_backend_refresh
The age of the stale object.
.. _obj_stale.can_esi:
obj_stale.can_esi
Type: BOOL
Readable from: vcl_backend_refresh
If the stale object can be ESI processed, that is if setting
``resp.do_esi`` or adding ``esi`` to ``resp.filters`` in
``vcl_deliver {}`` would cause the response body to be ESI
processed.
.. _obj_stale.grace:
obj_stale.grace
Type: DURATION
Readable from: vcl_backend_refresh
The stale object's grace period in seconds.
.. _obj_stale.hits:
obj_stale.hits
Type: INT
Readable from: vcl_backend_refresh
The count of cache-hits on this stale object.
In `vcl_deliver` a value of 0 indicates a cache miss.
.. _obj_stale.http:
obj_stale.http.*
Type: HEADER
Readable from: vcl_backend_refresh
The HTTP headers stored in the stale object.
See req.http_ for general notes.
.. _obj_stale.keep:
obj_stale.keep
Type: DURATION
Readable from: vcl_backend_refresh
The stale object's keep period in seconds.
.. _obj_stale.proto:
obj_stale.proto
Type: STRING
Readable from: vcl_backend_refresh
The HTTP protocol version stored in the stale object.
.. _obj_stale.reason:
obj_stale.reason
Type: STRING
Readable from: vcl_backend_refresh
The HTTP reason phrase stored in the stale object.
.. _obj_stale.status:
obj_stale.status
Type: INT
Readable from: vcl_backend_refresh
The HTTP status code stored in the stale object.
More information in the `HTTP response status`_ section.
.. _obj_stale.storage:
obj_stale.storage
Type: STEVEDORE
Readable from: vcl_backend_refresh
The storage backend where this stale object is stored.
.. _obj_stale.time:
obj_stale.time
Type: TIME
Readable from: vcl_backend_refresh
The time the stale object was created from the perspective of the
server which generated it. This will roughly be equivalent to
``now`` - ``obj.age``.
.. _obj_stale.ttl:
obj_stale.ttl
Type: DURATION
Readable from: vcl_backend_refresh
The stale object's time to live, in seconds.
.. _obj_stale.uncacheable:
obj_stale.uncacheable
Type: BOOL
Readable from: vcl_backend_refresh
Whether the stale object is uncacheable (pass, hit-for-pass or
hit-for-miss).
.. _obj_stale.is_valid:
obj_stale.is_valid
Type: BOOL
Readable from: vcl_backend_refresh
Whether the stale object is still valid.
This is the object we found in cache. It cannot be modified.
.. _obj.age:
obj.age
Type: DURATION
Readable from: vcl_hit, vcl_deliver
The age of the object.
.. _obj.can_esi:
obj.can_esi
Type: BOOL
Readable from: vcl_hit, vcl_deliver
If the object can be ESI processed, that is if setting
``resp.do_esi`` or adding ``esi`` to ``resp.filters`` in
``vcl_deliver {}`` would cause the response body to be ESI
processed.
.. _obj.grace:
obj.grace
Type: DURATION
Readable from: vcl_hit, vcl_deliver
The object's grace period in seconds.
.. _obj.hits:
obj.hits
Type: INT
Readable from: vcl_hit, vcl_deliver
The count of cache-hits on this object.
In `vcl_deliver` a value of 0 indicates a cache miss.
.. _obj.http:
obj.http.*
Type: HEADER
Readable from: vcl_hit
The HTTP headers stored in the object.
See req.http_ for general notes.
.. _obj.keep:
obj.keep
Type: DURATION
Readable from: vcl_hit, vcl_deliver
The object's keep period in seconds.
.. _obj.proto:
obj.proto
Type: STRING
Readable from: vcl_hit
The HTTP protocol version stored in the object.
.. _obj.reason:
obj.reason
Type: STRING
Readable from: vcl_hit
The HTTP reason phrase stored in the object.
.. _obj.status:
obj.status
Type: INT
Readable from: vcl_hit
The HTTP status code stored in the object.
More information in the `HTTP response status`_ section.
.. _obj.storage:
obj.storage
Type: STEVEDORE
Readable from: vcl_hit, vcl_deliver
The storage backend where this object is stored.
.. _obj.time:
obj.time
Type: TIME
Readable from: vcl_hit, vcl_deliver
The time the object was created from the perspective of the
server which generated it. This will roughly be equivalent to
``now`` - ``obj.age``.
.. _obj.ttl:
obj.ttl
Type: DURATION
Readable from: vcl_hit, vcl_deliver
The object's remaining time to live, in seconds.
.. _obj.uncacheable:
obj.uncacheable
Type: BOOL
Readable from: vcl_deliver
Whether the object is uncacheable (pass, hit-for-pass or
hit-for-miss).
This is the response we send to the client, it is built from either
beresp (pass/miss), obj (hits) or created from whole cloth (synth).
With the exception of resp.body all resp.* variables available
in both vcl_deliver{} and vcl_synth{} as a matter of symmetry.
resp
Type: HTTP
Readable from: vcl_deliver, vcl_synth
The entire response HTTP data structure, useful as argument
to VMODs.
.. _resp.body:
resp.body
Type: BODY
Writable from: vcl_synth
To produce a synthetic response body, for instance for errors.
.. _resp.do_esi:
resp.do_esi VCL >= 4.1
Type: BOOL
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
Default: obj.can_esi
This can be used to selectively disable ESI processing, even
though ESI parsing happened during fetch (see beresp.do_esi).
This is useful when Varnish caches peer with each other.
It is a VCL error to use resp.do_esi after setting resp.filters.
.. _resp.filters:
resp.filters
Type: STRING
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
List of VDP filters the resp.body will be pushed through.
Before resp.filters is set, the value read will be the default
filter list as determined by varnish based on resp.do_esi and
request headers.
After resp.filters is set, changing any of the conditions
which otherwise determine the filter selection will have no
effect. Using resp.do_esi is an error once resp.filters is
set.
.. _resp.http:
resp.http.*
Type: HEADER
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
Unsettable from: vcl_deliver, vcl_synth
The HTTP headers that will be returned.
See req.http_ for general notes.
resp.http.content-length
Type: HEADER
Readable from: vcl_deliver, vcl_synth
The content-length header field is protected, see protected_headers_.
resp.http.transfer-encoding
Type: HEADER
Readable from: vcl_deliver, vcl_synth
The transfer-encoding header field is protected, see protected_headers_.
.. _resp.is_streaming:
resp.is_streaming
Type: BOOL
Readable from: vcl_deliver, vcl_synth
Returns true when the response will be streamed
while being fetched from the backend.
resp.proto VCL <= 4.0
Type: STRING
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
The HTTP protocol version to use for the response.
.. _resp.proto:
resp.proto VCL >= 4.1
Type: STRING
Readable from: vcl_deliver, vcl_synth
The HTTP protocol version to use for the response.
.. _resp.reason:
resp.reason
Type: STRING
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
The HTTP status message that will be returned.
.. _resp.status:
resp.status
Type: INT
Readable from: vcl_deliver, vcl_synth
Writable from: vcl_deliver, vcl_synth
The HTTP status code that will be returned.
More information in the `HTTP response status`_ section.
resp.status 200 will get changed into 304 by core code after
a return(deliver) from vcl_deliver for conditional requests
to cached content if validation succeeds.
For the validation, first ``req.http.If-None-Match`` is
compared against ``resp.http.Etag``. If they compare equal
according to the rules for weak validation (see RFC7232), a
304 is sent.
Secondly, ``req.http.If-Modified-Since`` is compared against
``resp.http.Last-Modified`` or, if it is unset or weak, against
the point in time when the object was last modified based on the
``Date`` and ``Age`` headers received with the backend
response which created the object. If the object has not been
modified based on that comparison, a 304 is sent.
.. _resp.time:
resp.time
Type: TIME
Readable from: vcl_deliver, vcl_synth
The time when we started preparing the response, just before
entering ``vcl_synth {}`` or ``vcl_deliver {}``.
.. _now:
now
Type: TIME
Readable from: all
The current time, in seconds since the UNIX epoch.
When converted to STRING in expressions it returns
a formatted timestamp like ``Tue, 20 Feb 2018 09:30:31 GMT``
``now`` remains stable for the duration of any built-in VCL
subroutine to make time-based calculations predictable and
avoid edge cases.
In other words, even if considerable amounts of time are spent
in VCL, ``now`` will always represent the point in time when
the respective built-in VCL subroutine was entered. ``now`` is
thus not suitable for any kind of time measurements. See
:ref:`std.timestamp()`, :ref:`std.now()` and
:ref:`std.timed_call()` in :ref:`vmod_std(3)`.
A session corresponds to the "conversation" that Varnish has with a single client connection, over which one or more request/response transactions may take place. It may comprise the traffic over an HTTP/1 keep-alive connection, or the multiplexed traffic over an HTTP/2 connection.
.. _sess.idle_send_timeout:
sess.idle_send_timeout
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Send timeout for individual pieces of data on client
connections, defaults to the ``idle_send_timeout`` parameter,
see :ref:`varnishd(1)`
.. _sess.send_timeout:
sess.send_timeout
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Total timeout for ordinary HTTP1 responses, defaults to the
``send_timeout`` parameter, see :ref:`varnishd(1)`
.. _sess.timeout_idle:
sess.timeout_idle
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Idle timeout for this session, defaults to the
``timeout_idle`` parameter, see :ref:`varnishd(1)`
.. _sess.timeout_linger:
sess.timeout_linger
Type: DURATION
Readable from: client
Writable from: client
Unsettable from: client
Linger timeout for this session, defaults to the
``timeout_linger`` parameter, see :ref:`varnishd(1)`
.. _sess.xid:
sess.xid VCL >= 4.1
Type: INT
Readable from: client, backend
Unique ID of this session.
.. XXX all of these are actually defined in generate.py
.. _storage.free_space:
storage.<name>.free_space
Type: BYTES
Readable from: client, backend
Default: 0
Free space available in the named stevedore. Only available for
the malloc stevedore.
.. _storage.happy:
storage.<name>.happy
Type: BOOL
Readable from: client, backend
Default: true
Health status for the named stevedore. Not available in any of the
current stevedores.
.. _storage.used_space:
storage.<name>.used_space
Type: BYTES
Readable from: client, backend
Default: 0
Used space in the named stevedore. Only available for the malloc
stevedore.
Some of the global runtime parameters related to VCL transactions are readable anywhere in VCL. The value of a parameter can change between accesses, it is not cached for the duration of a VCL task.
param.backend_idle_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_backend_idle_timeout`.
param.backend_wait_limit
Type: INT
Readable from: all
Global parameter :ref:`ref_param_backend_wait_limit`.
param.backend_wait_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_backend_wait_timeout`.
param.between_bytes_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_between_bytes_timeout`.
param.connect_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_connect_timeout`.
param.default_grace
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_default_grace`.
param.default_keep
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_default_keep`.
param.default_ttl
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_default_ttl`.
param.first_byte_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_first_byte_timeout`.
param.idle_send_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_idle_send_timeout`.
param.max_esi_depth
Type: INT
Readable from: all
Global parameter :ref:`ref_param_max_esi_depth`.
param.max_restarts
Type: INT
Readable from: all
Global parameter :ref:`ref_param_max_restarts`.
param.max_retries
Type: INT
Readable from: all
Global parameter :ref:`ref_param_max_retries`.
param.pipe_task_deadline
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_pipe_task_deadline`.
param.pipe_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_pipe_timeout`.
param.send_timeout
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_send_timeout`.
param.shortlived
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_shortlived`.
param.timeout_idle
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_timeout_idle`.
param.transit_buffer
Type: BYTES
Readable from: all
Global parameter :ref:`ref_param_transit_buffer`.
param.uncacheable_ttl
Type: DURATION
Readable from: all
Global parameter :ref:`ref_param_uncacheable_ttl`.