File: //proc/self/root/proc/thread-self/root/usr/share/doc/varnish-6.0.3/html/reference/vcl.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>VCL — Varnish version 6.0.3 documentation</title>
<link rel="stylesheet" href="../_static/classic.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/underscore.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="next" title="Varnish Processing States" href="states.html" />
<link rel="prev" title="The Varnish Reference Manual" href="index.html" />
</head><body>
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="states.html" title="Varnish Processing States"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="index.html" title="The Varnish Reference Manual"
accesskey="P">previous</a> |</li>
<li class="nav-item nav-item-0"><a href="../index.html">Varnish version 6.0.3 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="index.html" accesskey="U">The Varnish Reference Manual</a> »</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="section" id="vcl">
<span id="vcl-7"></span><h1>VCL<a class="headerlink" href="#vcl" title="Permalink to this headline">¶</a></h1>
<div class="section" id="varnish-configuration-language">
<h2>Varnish Configuration Language<a class="headerlink" href="#varnish-configuration-language" title="Permalink to this headline">¶</a></h2>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Manual section:</th><td class="field-body">7</td>
</tr>
</tbody>
</table>
<div class="section" id="description">
<h3>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h3>
<p>The VCL language is a small domain-specific language designed to be
used to describe request handling and document caching policies for
Varnish Cache.</p>
<p>When a new configuration is loaded, the varnishd management process
translates the VCL code to C and compiles it to a shared object which
is then loaded into the server process.</p>
<p>This document focuses on the syntax of the VCL language. For a full
description of syntax and semantics, with ample examples, please see
the online documentation at <a class="reference external" href="https://www.varnish-cache.org/docs/">https://www.varnish-cache.org/docs/</a> .</p>
<p>Starting with Varnish 4.0, each VCL file must start by declaring its
version with <code class="docutils literal notranslate"><span class="pre">vcl</span></code> <em><major>.<minor></em><code class="docutils literal notranslate"><span class="pre">;</span></code> marker at the top of
the file. See more about this under Versioning below.</p>
<div class="section" id="operators">
<h4>Operators<a class="headerlink" href="#operators" title="Permalink to this headline">¶</a></h4>
<p>The following operators are available in VCL:</p>
<blockquote>
<div><dl class="docutils">
<dt><code class="docutils literal notranslate"><span class="pre">=</span></code></dt>
<dd>Assignment operator.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">==</span></code></dt>
<dd>Comparison.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">~</span></code></dt>
<dd>Match. Can either be used with regular expressions or ACLs.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">!</span></code></dt>
<dd>Negation.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">&&</span></code></dt>
<dd>Logical and.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">||</span></code></dt>
<dd>Logical or.</dd>
</dl>
</div></blockquote>
</div>
<div class="section" id="conditionals">
<h4>Conditionals<a class="headerlink" href="#conditionals" title="Permalink to this headline">¶</a></h4>
<p>VCL has <code class="docutils literal notranslate"><span class="pre">if</span></code> and <code class="docutils literal notranslate"><span class="pre">else</span></code> statements. Nested logic can be
implemented with the <code class="docutils literal notranslate"><span class="pre">elseif</span></code> statement (<code class="docutils literal notranslate"><span class="pre">elsif</span></code>/<code class="docutils literal notranslate"><span class="pre">elif</span></code>/<code class="docutils literal notranslate"><span class="pre">else</span> <span class="pre">if</span></code> are equivalent).</p>
<p>Note that there are no loops or iterators of any kind in VCL.</p>
</div>
<div class="section" id="strings-booleans-time-duration-integers-and-real-numbers">
<h4>Strings, booleans, time, duration, integers and real numbers<a class="headerlink" href="#strings-booleans-time-duration-integers-and-real-numbers" title="Permalink to this headline">¶</a></h4>
<p>These are the data types in Varnish. You can <code class="docutils literal notranslate"><span class="pre">set</span></code> or <code class="docutils literal notranslate"><span class="pre">unset</span></code> these.</p>
<p>Example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="nb">set</span> <span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">User</span><span class="o">-</span><span class="n">Agent</span> <span class="o">=</span> <span class="s2">"unknown"</span><span class="p">;</span>
<span class="n">unset</span> <span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">Range</span><span class="p">;</span>
</pre></div>
</div>
<div class="section" id="strings">
<h5>Strings<a class="headerlink" href="#strings" title="Permalink to this headline">¶</a></h5>
<p>Basic strings are enclosed in double quotes <code class="docutils literal notranslate"><span class="pre">"</span></code><em>…</em><code class="docutils literal notranslate"><span class="pre">"</span></code>, and
may not contain newlines. Long strings are enclosed in
<code class="docutils literal notranslate"><span class="pre">{"</span></code><em>…</em><code class="docutils literal notranslate"><span class="pre">"}</span></code>. They may contain any character including single
double quotes <code class="docutils literal notranslate"><span class="pre">"</span></code>, newline and other control characters except for the
<em>NUL</em> (0x00) character.</p>
</div>
<div class="section" id="booleans">
<h5>Booleans<a class="headerlink" href="#booleans" title="Permalink to this headline">¶</a></h5>
<p>Booleans can be either <code class="docutils literal notranslate"><span class="pre">true</span></code> or <code class="docutils literal notranslate"><span class="pre">false</span></code>. In addition, in a boolean
context some data types will evaluate to <code class="docutils literal notranslate"><span class="pre">true</span></code> or <code class="docutils literal notranslate"><span class="pre">false</span></code> depending on
their value.</p>
<p>String types will evaluate to <code class="docutils literal notranslate"><span class="pre">false</span></code> if they are not set; backend types
will evaluate to <code class="docutils literal notranslate"><span class="pre">false</span></code> if they don’t have a backend assigned; integer
types will evaluate to <code class="docutils literal notranslate"><span class="pre">false</span></code> if their value is zero; duration types
will evaluate to <code class="docutils literal notranslate"><span class="pre">false</span></code> if their value is equal or less than zero.</p>
</div>
<div class="section" id="time">
<h5>Time<a class="headerlink" href="#time" title="Permalink to this headline">¶</a></h5>
<p>VCL has time. A duration can be added to a time to make another time.
In string context they return a formatted string in RFC1123 format,
e.g. <code class="docutils literal notranslate"><span class="pre">Sun,</span> <span class="pre">06</span> <span class="pre">Nov</span> <span class="pre">1994</span> <span class="pre">08:49:37</span> <span class="pre">GMT</span></code>.</p>
<p>The keyword <code class="docutils literal notranslate"><span class="pre">now</span></code> returns a time representing the current time in seconds
since the Epoch.</p>
</div>
<div class="section" id="durations">
<h5>Durations<a class="headerlink" href="#durations" title="Permalink to this headline">¶</a></h5>
<p>Durations are defined by a number followed by a unit. The number can
include a fractional part, e.g. <code class="docutils literal notranslate"><span class="pre">1.5s</span></code>. The supported units are:</p>
<blockquote>
<div><dl class="docutils">
<dt><code class="docutils literal notranslate"><span class="pre">ms</span></code></dt>
<dd>milliseconds</dd>
<dt><code class="docutils literal notranslate"><span class="pre">s</span></code></dt>
<dd>seconds</dd>
<dt><code class="docutils literal notranslate"><span class="pre">m</span></code></dt>
<dd>minutes</dd>
<dt><code class="docutils literal notranslate"><span class="pre">h</span></code></dt>
<dd>hours</dd>
<dt><code class="docutils literal notranslate"><span class="pre">d</span></code></dt>
<dd>days</dd>
<dt><code class="docutils literal notranslate"><span class="pre">w</span></code></dt>
<dd>weeks</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y</span></code></dt>
<dd>years</dd>
</dl>
</div></blockquote>
<p>In string context they return a string with their value rounded to
3 decimal places and excluding the unit, e.g. <code class="docutils literal notranslate"><span class="pre">1.500</span></code>.</p>
</div>
<div class="section" id="integers">
<h5>Integers<a class="headerlink" href="#integers" title="Permalink to this headline">¶</a></h5>
<p>Certain fields are integers, used as expected. In string context they
return a string, e.g. <code class="docutils literal notranslate"><span class="pre">1234</span></code>.</p>
</div>
<div class="section" id="real-numbers">
<h5>Real numbers<a class="headerlink" href="#real-numbers" title="Permalink to this headline">¶</a></h5>
<p>VCL understands real numbers. In string context they return a string
with their value rounded to 3 decimal places, e.g. <code class="docutils literal notranslate"><span class="pre">3.142</span></code>.</p>
</div>
</div>
<div class="section" id="regular-expressions">
<h4>Regular Expressions<a class="headerlink" href="#regular-expressions" title="Permalink to this headline">¶</a></h4>
<p>Varnish uses Perl-compatible regular expressions (PCRE). For a
complete description please see the pcre(3) man page.</p>
<p>To send flags to the PCRE engine, such as to do case insensitive matching, add
the flag within parens following a question mark, like this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span># If host is NOT example dot com..
if (req.http.host !~ "(?i)example\.com$") {
...
}
</pre></div>
</div>
</div>
<div class="section" id="include-statement">
<h4>Include statement<a class="headerlink" href="#include-statement" title="Permalink to this headline">¶</a></h4>
<p>To include a VCL file in another file use the include keyword:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">include</span> <span class="s2">"foo.vcl"</span><span class="p">;</span>
</pre></div>
</div>
</div>
<div class="section" id="import-statement">
<h4>Import statement<a class="headerlink" href="#import-statement" title="Permalink to this headline">¶</a></h4>
<p>The <code class="docutils literal notranslate"><span class="pre">import</span></code> statement is used to load Varnish Modules (VMODs.)</p>
<p>Example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">std</span><span class="p">;</span>
<span class="n">sub</span> <span class="n">vcl_recv</span> <span class="p">{</span>
<span class="n">std</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="comments">
<h4>Comments<a class="headerlink" href="#comments" title="Permalink to this headline">¶</a></h4>
<p>Single lines of VCL can be commented out using <code class="docutils literal notranslate"><span class="pre">//</span></code> or
<code class="docutils literal notranslate"><span class="pre">#</span></code>. Multi-line blocks can be commented out with
<code class="docutils literal notranslate"><span class="pre">/*</span></code><em>block</em><code class="docutils literal notranslate"><span class="pre">*/</span></code>.</p>
<p>Example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_recv</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">Single</span> <span class="n">line</span> <span class="n">of</span> <span class="n">out</span><span class="o">-</span><span class="n">commented</span> <span class="n">VCL</span><span class="o">.</span>
<span class="c1"># Another way of commenting out a single line.</span>
<span class="o">/*</span>
<span class="n">Multi</span><span class="o">-</span><span class="n">line</span> <span class="n">block</span> <span class="n">of</span> <span class="n">commented</span><span class="o">-</span><span class="n">out</span> <span class="n">VCL</span><span class="o">.</span>
<span class="o">*/</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="backend-definition">
<span id="id1"></span><h4>Backend definition<a class="headerlink" href="#backend-definition" title="Permalink to this headline">¶</a></h4>
<p>A backend declaration creates and initialises a named backend object. A
declaration start with the keyword <code class="docutils literal notranslate"><span class="pre">backend</span></code> followed by the name of the
backend. The actual declaration is in curly brackets, in a key/value fashion.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">backend</span> <span class="n">name</span> <span class="p">{</span>
<span class="o">.</span><span class="n">attribute</span> <span class="o">=</span> <span class="s2">"value"</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>One of the attributes <code class="docutils literal notranslate"><span class="pre">.host</span></code> or <code class="docutils literal notranslate"><span class="pre">.path</span></code> is mandatory (but not
both). The attributes will inherit their defaults from the global
parameters. The following attributes are available:</p>
<blockquote>
<div><dl class="docutils">
<dt><code class="docutils literal notranslate"><span class="pre">.host</span></code></dt>
<dd>The host to be used. IP address or a hostname that resolves to a
single IP address. This attribute is mandatory, unless <code class="docutils literal notranslate"><span class="pre">.path</span></code>
is declared.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.path</span></code> (<code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code>)</dt>
<dd>The absolute path of a Unix domain socket at which a backend is
listening. The file at that path must exist and must be accessible
to Varnish at VCL load time, and it must be a socket. One of
<code class="docutils literal notranslate"><span class="pre">.path</span></code> or <code class="docutils literal notranslate"><span class="pre">.host</span></code> must be declared (but not both). <code class="docutils literal notranslate"><span class="pre">.path</span></code>
may only be used in VCL since version 4.1.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.port</span></code></dt>
<dd>The port on the backend that Varnish should connect to. Ignored if
a Unix domain socket is declared in <code class="docutils literal notranslate"><span class="pre">.path</span></code>.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.host_header</span></code></dt>
<dd>A host header to add to probes and regular backend requests if they have no
such header.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.connect_timeout</span></code></dt>
<dd><p class="first">Timeout for connections.</p>
<p class="last">Default: <code class="docutils literal notranslate"><span class="pre">connect_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.first_byte_timeout</span></code></dt>
<dd><p class="first">Timeout for first byte.</p>
<p class="last">Default: <code class="docutils literal notranslate"><span class="pre">first_byte_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.between_bytes_timeout</span></code></dt>
<dd><p class="first">Timeout between bytes.</p>
<p class="last">Default: <code class="docutils literal notranslate"><span class="pre">between_bytes_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.probe</span></code></dt>
<dd>Attach a probe to the backend. See <a class="reference internal" href="#probes">Probes</a></dd>
<dt><code class="docutils literal notranslate"><span class="pre">.proxy_header</span></code></dt>
<dd><p class="first">The PROXY protocol version Varnish should use when connecting to
this backend. Allowed values are <code class="docutils literal notranslate"><span class="pre">1</span></code> and <code class="docutils literal notranslate"><span class="pre">2</span></code>.</p>
<p><em>Notice</em> this setting will lead to backend connections being used
for a single request only (subject to future improvements). Thus,
extra care should be taken to avoid running into failing backend
connections with EADDRNOTAVAIL due to no local ports being
available. Possible options are:</p>
<ul class="last simple">
<li>Use additional backend connections to extra IP addresses or TCP
ports</li>
<li>Increase the number of available ports (Linux sysctl
<code class="docutils literal notranslate"><span class="pre">net.ipv4.ip_local_port_range</span></code>)</li>
<li>Reuse backend connection ports early (Linux sysctl
<code class="docutils literal notranslate"><span class="pre">net.ipv4.tcp_tw_reuse</span></code>)</li>
</ul>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.max_connections</span></code></dt>
<dd>Maximum number of open connections towards this backend. If
Varnish reaches the maximum Varnish it will start failing
connections.</dd>
</dl>
</div></blockquote>
<p>Backends can be used with <em>directors</em>. Please see the
<a class="reference internal" href="vmod_generated.html#vmod-directors-3"><span class="std std-ref">vmod_directors</span></a> man page for more information.</p>
</div>
<div class="section" id="probes">
<span id="reference-vcl-probes"></span><h4>Probes<a class="headerlink" href="#probes" title="Permalink to this headline">¶</a></h4>
<p>Probes will query the backend for status on a regular basis and mark
the backend as down it they fail. A probe is defined as this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">probe</span> <span class="n">name</span> <span class="p">{</span>
<span class="o">.</span><span class="n">attribute</span> <span class="o">=</span> <span class="s2">"value"</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The probe named <code class="docutils literal notranslate"><span class="pre">default</span></code> is special and will be used for all backends
which do not explicitly reference a probe.</p>
<p>There are no mandatory options. These are the options you can set:</p>
<blockquote>
<div><dl class="docutils">
<dt><code class="docutils literal notranslate"><span class="pre">.url</span></code></dt>
<dd>The URL to query. Defaults to <code class="docutils literal notranslate"><span class="pre">/</span></code>.
Mutually exclusive with <code class="docutils literal notranslate"><span class="pre">.request</span></code></dd>
<dt><code class="docutils literal notranslate"><span class="pre">.request</span></code></dt>
<dd><p class="first">Specify a full HTTP request using multiple strings. <code class="docutils literal notranslate"><span class="pre">.request</span></code> will
have <code class="docutils literal notranslate"><span class="pre">\r\n</span></code> automatically inserted after every string.
Mutually exclusive with <code class="docutils literal notranslate"><span class="pre">.url</span></code>.</p>
<p class="last"><em>Note</em> that probes require the backend to complete sending the
response and close the connection within the specified timeout, so
<code class="docutils literal notranslate"><span class="pre">.request</span></code> will, for <code class="docutils literal notranslate"><span class="pre">HTTP/1.1</span></code>, most likely need to contain a
<code class="docutils literal notranslate"><span class="pre">"Connection:</span> <span class="pre">close"</span></code> string.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.expected_response</span></code></dt>
<dd>The expected HTTP response code. Defaults to <code class="docutils literal notranslate"><span class="pre">200</span></code>.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.timeout</span></code></dt>
<dd>The timeout for the probe. Default is <code class="docutils literal notranslate"><span class="pre">2s</span></code>.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.interval</span></code></dt>
<dd>How often the probe is run. Default is <code class="docutils literal notranslate"><span class="pre">5s</span></code>.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.initial</span></code></dt>
<dd>How many of the polls in <code class="docutils literal notranslate"><span class="pre">.window</span></code> are considered good when Varnish
starts. Defaults to the value of <code class="docutils literal notranslate"><span class="pre">.threshold</span></code> - 1. In this case, the
backend starts as sick and requires one single poll to be
considered healthy.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.window</span></code></dt>
<dd>How many of the latest polls we examine to determine backend health.
Defaults to <code class="docutils literal notranslate"><span class="pre">8</span></code>.</dd>
<dt><code class="docutils literal notranslate"><span class="pre">.threshold</span></code></dt>
<dd>How many of the polls in <code class="docutils literal notranslate"><span class="pre">.window</span></code> must have succeeded to
consider the backend to be healthy.
Defaults to <code class="docutils literal notranslate"><span class="pre">3</span></code>.</dd>
</dl>
</div></blockquote>
</div>
<div class="section" id="access-control-list-acl">
<h4>Access Control List (ACL)<a class="headerlink" href="#access-control-list-acl" title="Permalink to this headline">¶</a></h4>
<p>An Access Control List (ACL) declaration creates and initialises a named access
control list which can later be used to match client addresses:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>acl localnetwork {
"localhost"; # myself
"192.0.2.0"/24; # and everyone on the local network
! "192.0.2.23"; # except for the dial-in router
}
</pre></div>
</div>
<p>If an ACL entry specifies a host name which Varnish is unable to
resolve, it will match any address it is compared to. Consequently,
if it is preceded by a negation mark, it will reject any address it is
compared to, which may not be what you intended. If the entry is
enclosed in parentheses, however, it will simply be ignored.</p>
<p>To match an IP address against an ACL, simply use the match operator:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">client</span><span class="o">.</span><span class="n">ip</span> <span class="o">~</span> <span class="n">localnetwork</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="p">(</span><span class="n">pipe</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="vcl-objects">
<h4>VCL objects<a class="headerlink" href="#vcl-objects" title="Permalink to this headline">¶</a></h4>
<p>A VCL object can be instantiated with the <code class="docutils literal notranslate"><span class="pre">new</span></code> keyword:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_init</span> <span class="p">{</span>
<span class="n">new</span> <span class="n">b</span> <span class="o">=</span> <span class="n">directors</span><span class="o">.</span><span class="n">round_robin</span><span class="p">()</span>
<span class="n">b</span><span class="o">.</span><span class="n">add_backend</span><span class="p">(</span><span class="n">node1</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>This is only available in <code class="docutils literal notranslate"><span class="pre">vcl_init</span></code>.</p>
</div>
<div class="section" id="subroutines">
<h4>Subroutines<a class="headerlink" href="#subroutines" title="Permalink to this headline">¶</a></h4>
<p>A subroutine is used to group code for legibility or reusability:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">pipe_if_local</span> <span class="p">{</span>
<span class="k">if</span> <span class="p">(</span><span class="n">client</span><span class="o">.</span><span class="n">ip</span> <span class="o">~</span> <span class="n">localnetwork</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="p">(</span><span class="n">pipe</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Subroutines in VCL do not take arguments, nor do they return
values. The built in subroutines all have names beginning with <code class="docutils literal notranslate"><span class="pre">vcl_</span></code>,
which is reserved.</p>
<p>To call a subroutine, use the <code class="docutils literal notranslate"><span class="pre">call</span></code> keyword followed by the
subroutine’s name:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_recv</span> <span class="p">{</span>
<span class="n">call</span> <span class="n">pipe_if_local</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="section" id="return-statements">
<h5>Return statements<a class="headerlink" href="#return-statements" title="Permalink to this headline">¶</a></h5>
<p>The ongoing <code class="docutils literal notranslate"><span class="pre">vcl_*</span></code> subroutine execution ends when a
<code class="docutils literal notranslate"><span class="pre">return(</span></code><em><action></em><code class="docutils literal notranslate"><span class="pre">)</span></code> statement is made.</p>
<p>The <em><action></em> specifies how execution should proceed. The context
defines which actions are available.</p>
</div>
<div class="section" id="multiple-subroutines">
<h5>Multiple subroutines<a class="headerlink" href="#multiple-subroutines" title="Permalink to this headline">¶</a></h5>
<p>If multiple subroutines with the name of one of the built-in ones are defined,
they are concatenated in the order in which they appear in the source.</p>
<p>The built-in VCL distributed with Varnish will be implicitly concatenated
when the VCL is compiled.</p>
</div>
</div>
<div class="section" id="vcl-variables">
<span id="id2"></span><h4>VCL Variables<a class="headerlink" href="#vcl-variables" title="Permalink to this headline">¶</a></h4>
<p>Variables provide read, write and delete access to almost all aspects
of the work at hand.</p>
<p>Reading a variable is done simply by using its name in VCL:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">client</span><span class="o">.</span><span class="n">ip</span> <span class="o">~</span> <span class="n">bad_guys</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="p">(</span><span class="n">synth</span><span class="p">(</span><span class="mi">400</span><span class="p">));</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Writing a variable, where this is possible, is done with a <cite>set</cite>
statement:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="nb">set</span> <span class="n">resp</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">never</span> <span class="o">=</span> <span class="s2">"Let You Down"</span><span class="p">;</span>
</pre></div>
</div>
<p>Similarly, deleting a variable, for the few variables where this is
possible, is done with a <cite>unset</cite> statement:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">unset</span> <span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">cookie</span><span class="p">;</span>
</pre></div>
</div>
<p>Which operations are possible on each variable is described below,
often with the shorthand “backend” which covers the <cite>vcl_backend_*</cite>
methods and “client” which covers the rest, except <cite>vcl_init</cite> and
<cite>vcl_fini</cite>.</p>
<p>When setting a variable, the right hand side of the equal sign
must have the variables type, you cannot assign a STRING to
a variable of type NUMBER, even if the string is <cite>“42”</cite>.
(Explicit conversion functions can be found in
<a class="reference internal" href="vmod_generated.html#vmod-std-3"><span class="std std-ref">vmod_std</span></a>).</p>
<div class="section" id="local-server-remote-and-client">
<h5>local, server, remote and client<a class="headerlink" href="#local-server-remote-and-client" title="Permalink to this headline">¶</a></h5>
<p>These variables describe the network connection between the
client and varnishd.</p>
<p>Without PROXY protocol:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span> <span class="n">client</span> <span class="n">server</span>
<span class="n">remote</span> <span class="n">local</span>
<span class="n">v</span> <span class="n">v</span>
<span class="n">CLIENT</span> <span class="o">------------</span> <span class="n">VARNISHD</span>
</pre></div>
</div>
<p>With PROXY protocol:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span> <span class="n">client</span> <span class="n">server</span> <span class="n">remote</span> <span class="n">local</span>
<span class="n">v</span> <span class="n">v</span> <span class="n">v</span> <span class="n">v</span>
<span class="n">CLIENT</span> <span class="o">------------</span> <span class="n">PROXY</span> <span class="o">------------</span> <span class="n">VARNISHD</span>
</pre></div>
</div>
<p>local.ip</p>
<blockquote>
<div><p>Type: IP</p>
<p>Readable from: client, backend</p>
<p>The IP address (and port number) of the local end of the
TCP connection, for instance <cite>192.168.1.1:81</cite></p>
<p>If the connection is a UNIX domain socket, the value
will be <cite>0.0.0.0:0</cite></p>
</div></blockquote>
<p>local.endpoint <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client, backend</p>
<p>The address of the ‘-a’ socket the session was accepted on.</p>
<p>If the argument was <cite>-a foo=:81</cite> this would be “:81”</p>
</div></blockquote>
<p>local.socket <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client, backend</p>
<p>The name of the ‘-a’ socket the session was accepted on.</p>
<p>If the argument was <cite>-a foo=:81</cite> this would be “foo”.</p>
<p>Note that all ‘-a’ gets a default name on the form <cite>a%d</cite>
if no name is provided.</p>
</div></blockquote>
<p>remote.ip</p>
<blockquote>
<div><p>Type: IP</p>
<p>Readable from: client, backend</p>
<p>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.</p>
<p>If the connection is a UNIX domain socket, the value
will be <cite>0.0.0.0:0</cite></p>
</div></blockquote>
<p>client.ip</p>
<blockquote>
<div><p>Type: IP</p>
<p>Readable from: client, backend</p>
<p>The client’s IP address, either the same as <cite>local.ip</cite>
or what the PROXY protocol told us.</p>
</div></blockquote>
<p>client.identity</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Identification of the client, used to load balance
in the client director. Defaults to <cite>client.ip</cite></p>
<p>This variable can be overwritten with more precise
information, for instance extracted from a <cite>Cookie:</cite>
header.</p>
</div></blockquote>
<p>server.ip</p>
<blockquote>
<div><p>Type: IP</p>
<p>Readable from: client, backend</p>
<p>The IP address of the socket on which the client
connection was received, either the same as <cite>server.ip</cite>
or what the PROXY protocol told us.</p>
</div></blockquote>
<p>server.hostname</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: all</p>
<p>The host name of the server, as returned by the
<cite>gethostname(3)</cite> system function.</p>
</div></blockquote>
<p>server.identity</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: all</p>
<p>The identity of the server, as set by the <cite>-i</cite> parameter.</p>
<p>If an <cite>-i</cite> parameter is not passed to varnishd, the return
value from <cite>gethostname(3)</cite> system function will be used.</p>
</div></blockquote>
</div>
<div class="section" id="req-and-req-top">
<h5>req and req_top<a class="headerlink" href="#req-and-req-top" title="Permalink to this headline">¶</a></h5>
<p>These variables describe the present request, and when ESI:include
requests are being processed, req_top points to the request received
from the client.</p>
<p>req</p>
<blockquote>
<div><p>Type: HTTP</p>
<p>Readable from: client</p>
<p>The entire request HTTP data structure.
Mostly useful for passing to VMODs.</p>
</div></blockquote>
<p>req.method</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>The request method (e.g. “GET”, “HEAD”, …)</p>
</div></blockquote>
<p>req.hash</p>
<blockquote>
<div><p>Type: BLOB</p>
<p>Readable from: vcl_hit, vcl_miss, vcl_pass, vcl_purge, vcl_deliver</p>
<p>The hash key of this request.
Mostly useful for passing to VMODs, but can also be useful
for debugging hit/miss status.</p>
</div></blockquote>
<p>req.url</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>The requested URL, for instance “/robots.txt”.</p>
</div></blockquote>
<p>req.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>The HTTP protocol version used by the client, usually “HTTP/1.1”
or “HTTP/2.0”.</p>
</div></blockquote>
<p>req.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>The HTTP protocol version used by the client, usually “HTTP/1.1”
or “HTTP/2.0”.</p>
</div></blockquote>
<p>req.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Unsetable from: client</p>
<p>The headers of request, things like <cite>req.http.date</cite>.</p>
<p>The RFCs allow multiple headers with the same name, and both
<cite>set</cite> and <cite>unset</cite> will remove <em>all</em> headers with the name given.</p>
</div></blockquote>
<p>req.restarts</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: client</p>
<p>A count of how many times this request has been restarted.</p>
</div></blockquote>
<p>req.storage</p>
<blockquote>
<div><p>Type: STEVEDORE</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>The storage backend to use to save this request body.</p>
</div></blockquote>
<p>req.esi_level</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: client</p>
<p>A count of how many levels of ESI requests we’re currently at.</p>
</div></blockquote>
<p>req.ttl</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Upper limit on the object age for cache lookups to return hit.</p>
</div></blockquote>
<p>req.grace</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Upper limit on the object grace.</p>
<p>During lookup the minimum of req.grace and the object’s stored
grace value will be used as the object’s grace.</p>
</div></blockquote>
<p>req.xid</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>Unique ID of this request.</p>
</div></blockquote>
<p>req.esi <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Set to <cite>false</cite> to disable ESI processing
regardless of any value in beresp.do_esi. Defaults
to <cite>true</cite>. This variable is replaced by <cite>resp.do_esi</cite>
in VCL 4.1.</p>
</div></blockquote>
<p>req.can_gzip</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>True if the client provided <cite>gzip</cite> or <cite>x-gzip</cite> in the
<cite>Accept-Encoding</cite> header.</p>
</div></blockquote>
<p>req.backend_hint</p>
<blockquote>
<div><p>Type: BACKEND</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>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.</p>
</div></blockquote>
<p>req.hash_ignore_busy</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Default: <cite>false</cite></p>
<p>Ignore any busy object during cache lookup.</p>
<p>You only want to do this when you have two server looking
up content sideways from each other to avoid deadlocks.</p>
</div></blockquote>
<p>req.hash_always_miss</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>Writable from: client</p>
<p>Default: <cite>false</cite></p>
<p>Force a cache miss for this request, even if perfectly
good matching objects are in the cache.</p>
<p>This is useful to force-update the cache without invalidating
existing entries in case the fetch fails.</p>
</div></blockquote>
<p>req.is_hitmiss</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>If this request resulted in a hitmiss</p>
</div></blockquote>
<p>req.is_hitpass</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client</p>
<p>If this request resulted in a hitpass</p>
</div></blockquote>
<p>req_top.method</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>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.</p>
</div></blockquote>
<p>req_top.url</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>The requested URL of the top-level request in a tree
of ESI requests.
Identical to req.url in non-ESI requests.</p>
</div></blockquote>
<p>req_top.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: client</p>
<p>HTTP headers of the top-level request in a tree of ESI requests.
Identical to req.http. in non-ESI requests.</p>
</div></blockquote>
<p>req_top.proto</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client</p>
<p>HTTP protocol version of the top-level request in a tree of
ESI requests.
Identical to req.proto in non-ESI requests.</p>
</div></blockquote>
</div>
<div class="section" id="bereq">
<h5>bereq<a class="headerlink" href="#bereq" title="Permalink to this headline">¶</a></h5>
<p>This is the request we send to the backend, it is built from the
clients <cite>req.*</cite> fields by filtering out “per-hop” fields which
should not be passed along (<cite>Connection:</cite>, <cite>Range:</cite> and similar).</p>
<p>Slightly more fields are allowed through for <cite>pass</cite> fetches
than for <cite>miss</cite> fetches, for instance <cite>Range</cite>.</p>
<p>bereq</p>
<blockquote>
<div><p>Type: HTTP</p>
<p>Readable from: backend</p>
<p>The entire backend request HTTP data structure.
Mostly useful as argument to VMODs.</p>
</div></blockquote>
<p>bereq.xid</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: backend</p>
<p>Unique ID of this request.</p>
</div></blockquote>
<p>bereq.retries</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: backend</p>
<p>A count of how many times this request has been retried.</p>
</div></blockquote>
<p>bereq.backend</p>
<blockquote>
<div><p>Type: BACKEND</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>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.</p>
</div></blockquote>
<p>bereq.body</p>
<blockquote>
<div><p>Type: BODY</p>
<p>Unsetable from: vcl_backend_fetch</p>
<p>The request body, only present on <cite>pass</cite> requests.</p>
<p>Unset will also remove <cite>bereq.http.Content-Length</cite>.</p>
</div></blockquote>
<p>bereq.hash</p>
<blockquote>
<div><p>Type: BLOB</p>
<p>Readable from: vcl_pipe, backend</p>
<p>The hash key of this request, a copy of <cite>req.hash</cite>.</p>
</div></blockquote>
<p>bereq.method</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>The request type (e.g. “GET”, “HEAD”).</p>
<p>Regular (non-pipe, non-pass) fetches are always “GET”</p>
</div></blockquote>
<p>bereq.url</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>The requested URL, copied from <cite>req.url</cite></p>
</div></blockquote>
<p>bereq.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>The HTTP protocol version, “HTTP/1.1” unless a pass or pipe
request has “HTTP/1.0” in <cite>req.proto</cite></p>
</div></blockquote>
<p>bereq.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_pipe, backend</p>
<p>The HTTP protocol version, “HTTP/1.1” unless a pass or pipe
request has “HTTP/1.0” in <cite>req.proto</cite></p>
</div></blockquote>
<p>bereq.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>Unsetable from: vcl_pipe, backend</p>
<p>The headers to be sent to the backend.</p>
</div></blockquote>
<p>bereq.uncacheable</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: backend</p>
<p>Indicates whether this request is uncacheable due to a
<cite>pass</cite> in the client side or a hit on an hit-for-pass object.</p>
</div></blockquote>
<p>bereq.connect_timeout</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_pipe, backend</p>
<p>Writable from: vcl_pipe, backend</p>
<p>Default: <code class="docutils literal notranslate"><span class="pre">.connect_timeout</span></code> attribute from the
<a class="reference internal" href="#backend-definition"><span class="std std-ref">Backend definition</span></a>, which defaults to the
<code class="docutils literal notranslate"><span class="pre">connect_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
<p>The time in seconds to wait for a backend connection to be
established.</p>
</div></blockquote>
<p>bereq.first_byte_timeout</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: backend</p>
<p>Writable from: backend</p>
<p>Default: <code class="docutils literal notranslate"><span class="pre">.first_byte_timeout</span></code> attribute from the
<a class="reference internal" href="#backend-definition"><span class="std std-ref">Backend definition</span></a>, which defaults to the
<code class="docutils literal notranslate"><span class="pre">first_byte_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
<p>The time in seconds to wait getting the first byte back
from the backend. Not available in pipe mode.</p>
</div></blockquote>
<p>bereq.between_bytes_timeout</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: backend</p>
<p>Writable from: backend</p>
<p>Default: <code class="docutils literal notranslate"><span class="pre">.between_bytes_timeout</span></code> attribute from the
<a class="reference internal" href="#backend-definition"><span class="std std-ref">Backend definition</span></a>, which defaults to the
<code class="docutils literal notranslate"><span class="pre">between_bytes_timeout</span></code> parameter, see <a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></p>
<p>The time in seconds to wait between each received byte from the
backend. Not available in pipe mode.</p>
</div></blockquote>
<p>bereq.is_bgfetch</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: backend</p>
<p>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.</p>
</div></blockquote>
</div>
<div class="section" id="beresp">
<h5>beresp<a class="headerlink" href="#beresp" title="Permalink to this headline">¶</a></h5>
<p>The response received from the backend, one cache misses, the
store object is built from <cite>beresp</cite>.</p>
<p>beresp</p>
<blockquote>
<div><p>Type: HTTP</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>The entire backend response HTTP data structure, useful as
argument to VMOD functions.</p>
</div></blockquote>
<p>beresp.body</p>
<blockquote>
<div><p>Type: BODY</p>
<p>Writable from: vcl_backend_error</p>
<p>For producing a synthetic body.</p>
</div></blockquote>
<p>beresp.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>The HTTP protocol version the backend replied with.</p>
</div></blockquote>
<p>beresp.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>The HTTP protocol version the backend replied with.</p>
</div></blockquote>
<p>beresp.status</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>The HTTP status code returned by the server.</p>
<p>Status codes on the form XXYZZ can be set where
XXYZZ is less than 65536 and Y is [1…9].
Only YZZ will be sent back to clients.</p>
<p>XX can be therefore be used to pass information
around inside VCL, for instance <cite>return(synth(22404))</cite>
from <cite>vcl_recv{}</cite> to <cite>vcl_synth{}</cite></p>
</div></blockquote>
<p>beresp.reason</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>The HTTP status message returned by the server.</p>
</div></blockquote>
<p>beresp.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Unsetable from: vcl_backend_response, vcl_backend_error</p>
<p>The HTTP headers returned from the server.</p>
</div></blockquote>
<p>beresp.do_esi</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Default: false</p>
<p>Set it to true to parse the object for ESI directives.
Will only be honored if req.esi is true.</p>
</div></blockquote>
<p>beresp.do_stream</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Default: true</p>
<p>Deliver the object to the client while fetching the whole
object into varnish.</p>
<p>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.</p>
<p>This variable has no effect if do_esi is true or when the
response body is empty.</p>
</div></blockquote>
<p>beresp.do_gzip</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Default: false</p>
<p>Set to <cite>true</cite> to gzip the object while storing it.</p>
<p>If <cite>http_gzip_support</cite> is disabled, setting this variable
has no effect.</p>
</div></blockquote>
<p>beresp.do_gunzip</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Default: false</p>
<p>Set to <cite>true</cite> to gunzip the object while storing it in the
cache.</p>
<p>If <cite>http_gzip_support</cite> is disabled, setting this variable
has no effect.</p>
</div></blockquote>
<p>beresp.was_304</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>When <cite>true</cite> this indicates that we got a 304 response
to our conditional fetch from the backend and turned
that into <cite>beresp.status = 200</cite></p>
</div></blockquote>
<p>beresp.uncacheable</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Inherited from bereq.uncacheable, see there.</p>
<p>Setting this variable makes the object uncacheable.</p>
<p>This may may produce a hit-for-miss object in the cache.</p>
<p>Clearing the variable has no effect and will log the warning
“Ignoring attempt to reset beresp.uncacheable”.</p>
</div></blockquote>
<p>beresp.ttl</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>The object’s remaining time to live, in seconds.</p>
</div></blockquote>
<p>beresp.age</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>The age of the object.</p>
</div></blockquote>
<p>beresp.grace</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Set to a period to enable grace.</p>
</div></blockquote>
<p>beresp.keep</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Set to a period to enable conditional backend requests.</p>
<p>The keep time is cache lifetime in addition to the ttl.</p>
<p>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.</p>
</div></blockquote>
<p>beresp.backend</p>
<blockquote>
<div><p>Type: BACKEND</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>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.</p>
</div></blockquote>
<p>beresp.backend.name</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Name of the backend this response was fetched from.
Same as beresp.backend.</p>
</div></blockquote>
<p>beresp.backend.ip <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: IP</p>
<p>Readable from: vcl_backend_response</p>
<p>IP of the backend this response was fetched from.</p>
</div></blockquote>
<p>beresp.storage</p>
<blockquote>
<div><p>Type: STEVEDORE</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>The storage backend to use to save this object.</p>
</div></blockquote>
<p>beresp.storage_hint <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_backend_response, vcl_backend_error</p>
<p>Writable from: vcl_backend_response, vcl_backend_error</p>
<p>Deprecated since varnish 5.1 and discontinued since VCL
4.1 (varnish 6.0). Use beresp.storage instead.</p>
<p>Hint to Varnish that you want to save this object to a
particular storage backend.</p>
</div></blockquote>
</div>
<div class="section" id="obj">
<h5>obj<a class="headerlink" href="#obj" title="Permalink to this headline">¶</a></h5>
<p>This is the object we found in cache. It cannot be modified.</p>
<p>obj.proto</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_hit</p>
<p>The HTTP protocol version stored in the object.</p>
</div></blockquote>
<p>obj.status</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: vcl_hit</p>
<p>The HTTP status code stored in the object.</p>
</div></blockquote>
<p>obj.reason</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_hit</p>
<p>The HTTP reason phrase stored in the object.</p>
</div></blockquote>
<p>obj.hits</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The count of cache-hits on this object.</p>
<p>In <cite>vcl_deliver</cite> a value of 0 indicates a cache miss.</p>
</div></blockquote>
<p>obj.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: vcl_hit</p>
<p>The HTTP headers stored in the object.</p>
</div></blockquote>
<p>obj.ttl</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The object’s remaining time to live, in seconds.</p>
</div></blockquote>
<p>obj.age</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The age of the object.</p>
</div></blockquote>
<p>obj.grace</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The object’s grace period in seconds.</p>
</div></blockquote>
<p>obj.keep</p>
<blockquote>
<div><p>Type: DURATION</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The object’s keep period in seconds.</p>
</div></blockquote>
<p>obj.uncacheable</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_deliver</p>
<p>Whether the object is uncacheable (pass, hit-for-pass or
hit-for-miss).</p>
</div></blockquote>
<p>obj.storage</p>
<blockquote>
<div><p>Type: STEVEDORE</p>
<p>Readable from: vcl_hit, vcl_deliver</p>
<p>The storage backend where this object is stored.</p>
</div></blockquote>
</div>
<div class="section" id="resp">
<h5>resp<a class="headerlink" href="#resp" title="Permalink to this headline">¶</a></h5>
<p>This is the response we send to the client, it is built from either
<cite>beresp</cite> (pass/miss), <cite>obj</cite> (hits) or created from whole cloth (synth).</p>
<p>With the exception of <cite>resp.body</cite> all <cite>resp.*</cite> variables available
in both <cite>vcl_deliver{}</cite> and <cite>vcl_synth{}</cite> as a matter of symmetry.</p>
<p>resp</p>
<blockquote>
<div><p>Type: HTTP</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>The entire response HTTP data structure, useful as argument
to VMODs.</p>
</div></blockquote>
<p>resp.body</p>
<blockquote>
<div><p>Type: BODY</p>
<p>Writable from: vcl_synth</p>
<p>To produce a synthetic response body, for instance for errors.</p>
</div></blockquote>
<p>resp.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre"><=</span> <span class="pre">4.0</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>The HTTP protocol version to use for the response.</p>
</div></blockquote>
<p>resp.proto <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>The HTTP protocol version to use for the response.</p>
</div></blockquote>
<p>resp.status</p>
<blockquote>
<div><p>Type: INT</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>The HTTP status code that will be returned.</p>
<p>Assigning a HTTP standardized code to resp.status will also
set resp.reason to the corresponding status message.</p>
<p>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.</p>
</div></blockquote>
<p>resp.reason</p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>The HTTP status message that will be returned.</p>
</div></blockquote>
<p>resp.http.*</p>
<blockquote>
<div><p>Type: HEADER</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>Unsetable from: vcl_deliver, vcl_synth</p>
<p>The HTTP headers that will be returned.</p>
</div></blockquote>
<p>resp.do_esi <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Writable from: vcl_deliver, vcl_synth</p>
<p>Default: Set if ESI parsing has happened.</p>
<p>This can be used to selectively disable ESI processing,
even though ESI parsing happened during fetch.
This is useful when Varnish caches peer with each other.</p>
</div></blockquote>
<p>resp.is_streaming</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: vcl_deliver, vcl_synth</p>
<p>Returns true when the response will be streamed
while being fetched from the backend.</p>
</div></blockquote>
</div>
<div class="section" id="special-variables">
<h5>Special variables<a class="headerlink" href="#special-variables" title="Permalink to this headline">¶</a></h5>
<p>now</p>
<blockquote>
<div><p>Type: TIME</p>
<p>Readable from: all</p>
<p>The current time, in seconds since the UNIX epoch.</p>
<p>When converted to STRING in expressions it returns
a formatted timestamp like <cite>Tue, 20 Feb 2018 09:30:31 GMT</cite></p>
</div></blockquote>
</div>
<div class="section" id="sess">
<h5>sess<a class="headerlink" href="#sess" title="Permalink to this headline">¶</a></h5>
<p>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.</p>
<p>sess.xid <code class="docutils literal notranslate"><span class="pre">VCL</span> <span class="pre">>=</span> <span class="pre">4.1</span></code></p>
<blockquote>
<div><p>Type: STRING</p>
<p>Readable from: client, backend</p>
<p>Unique ID of this session.</p>
</div></blockquote>
</div>
<div class="section" id="storage">
<h5>storage<a class="headerlink" href="#storage" title="Permalink to this headline">¶</a></h5>
<p>storage.<name>.free_space</p>
<blockquote>
<div><p>Type: BYTES</p>
<p>Readable from: client, backend</p>
<p>Free space available in the named stevedore. Only available for
the malloc stevedore.</p>
</div></blockquote>
<p>storage.<name>.used_space</p>
<blockquote>
<div><p>Type: BYTES</p>
<p>Readable from: client, backend</p>
<p>Used space in the named stevedore. Only available for the malloc
stevedore.</p>
</div></blockquote>
<p>storage.<name>.happy</p>
<blockquote>
<div><p>Type: BOOL</p>
<p>Readable from: client, backend</p>
<p>Health status for the named stevedore. Not available in any of the
current stevedores.</p>
</div></blockquote>
</div>
</div>
<div class="section" id="functions">
<h4>Functions<a class="headerlink" href="#functions" title="Permalink to this headline">¶</a></h4>
<p>The following built-in functions are available:</p>
<div class="section" id="ban-string">
<span id="vcl-7-ban"></span><h5>ban(STRING)<a class="headerlink" href="#ban-string" title="Permalink to this headline">¶</a></h5>
<blockquote>
<div><p>Invalidates all objects in cache that match the given expression with the
ban mechanism.</p>
<p>The format of <em>STRING</em> is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o"><</span><span class="n">field</span><span class="o">></span> <span class="o"><</span><span class="n">operator</span><span class="o">></span> <span class="o"><</span><span class="n">arg</span><span class="o">></span> <span class="p">[</span><span class="o">&&</span> <span class="o"><</span><span class="n">field</span><span class="o">></span> <span class="o"><</span><span class="n">oper</span><span class="o">></span> <span class="o"><</span><span class="n">arg</span><span class="o">></span> <span class="o">...</span><span class="p">]</span>
</pre></div>
</div>
<ul class="simple">
<li><em><field></em>:<ul>
<li><code class="docutils literal notranslate"><span class="pre">req.url</span></code>: The request url</li>
<li><code class="docutils literal notranslate"><span class="pre">req.http.*</span></code>: Any request header</li>
<li><code class="docutils literal notranslate"><span class="pre">obj.status</span></code>: The cache object status</li>
<li><code class="docutils literal notranslate"><span class="pre">obj.http.*</span></code>: Any cache object header</li>
</ul>
</li>
<li><em><operator></em>:<ul>
<li><code class="docutils literal notranslate"><span class="pre">==</span></code>: <em><field></em> and <em><arg></em> are equal strings (case sensitive)</li>
<li><code class="docutils literal notranslate"><span class="pre">!=</span></code>: <em><field></em> and <em><arg></em> are unequal strings (case sensitive)</li>
<li><code class="docutils literal notranslate"><span class="pre">~</span></code>: <em><field></em> matches the regular expression <em><arg></em></li>
<li><code class="docutils literal notranslate"><span class="pre">!~</span></code>:<em><field></em> does not match the regular expression <em><arg></em></li>
</ul>
</li>
<li><em><arg></em>: Either a literal string or a regular expression. Note
that <em><arg></em> does not use any of the string delimiters like <code class="docutils literal notranslate"><span class="pre">"</span></code>
or <code class="docutils literal notranslate"><span class="pre">{"</span></code><em>…</em><code class="docutils literal notranslate"><span class="pre">"}</span></code> used elsewhere in varnish. To match
against strings containing whitespace, regular expressions
containing <code class="docutils literal notranslate"><span class="pre">\s</span></code> can be used.</li>
</ul>
<p>Expressions can be chained using the <em>and</em> operator <code class="docutils literal notranslate"><span class="pre">&&</span></code>. For <em>or</em>
semantics, use several bans.</p>
<p>The unset <em><field></em> is not equal to any string, such that, for a
non-existing header, the operators <code class="docutils literal notranslate"><span class="pre">==</span></code> and <code class="docutils literal notranslate"><span class="pre">~</span></code> always evaluate
as false, while the operators <code class="docutils literal notranslate"><span class="pre">!=</span></code> and <code class="docutils literal notranslate"><span class="pre">!~</span></code> always evaluate as
true, respectively, for any value of <em><arg></em>.</p>
</div></blockquote>
</div>
<div class="section" id="hash-data-input">
<h5>hash_data(input)<a class="headerlink" href="#hash-data-input" title="Permalink to this headline">¶</a></h5>
<blockquote>
<div>Adds an input to the hash input. In the built-in VCL <code class="docutils literal notranslate"><span class="pre">hash_data()</span></code>
is called on the host and URL of the request. Available in <code class="docutils literal notranslate"><span class="pre">vcl_hash</span></code>.</div></blockquote>
</div>
<div class="section" id="synthetic-string">
<h5>synthetic(STRING)<a class="headerlink" href="#synthetic-string" title="Permalink to this headline">¶</a></h5>
<blockquote>
<div><p>Prepare a synthetic response body containing the <em>STRING</em>. Available
in <code class="docutils literal notranslate"><span class="pre">vcl_synth</span></code> and <code class="docutils literal notranslate"><span class="pre">vcl_backend_error</span></code>.</p>
<p>Identical to <code class="docutils literal notranslate"><span class="pre">set</span> <span class="pre">resp.body</span></code> / <code class="docutils literal notranslate"><span class="pre">set</span> <span class="pre">beresp.body</span></code>.</p>
</div></blockquote>
</div>
<div class="section" id="regsub-str-regex-sub">
<h5>regsub(str, regex, sub)<a class="headerlink" href="#regsub-str-regex-sub" title="Permalink to this headline">¶</a></h5>
<blockquote>
<div>Returns a copy of <em>str</em> with the first occurrence of the regular
expression <em>regex</em> replaced with <em>sub</em>. Within <em>sub</em>, <code class="docutils literal notranslate"><span class="pre">\0</span></code> (which
can also be spelled <code class="docutils literal notranslate"><span class="pre">\&</span></code>) is replaced with the entire matched
string, and <code class="docutils literal notranslate"><span class="pre">\</span></code><em>n</em> is replaced with the contents of subgroup <em>n</em>
in the matched string.</div></blockquote>
</div>
<div class="section" id="regsuball-str-regex-sub">
<h5>regsuball(str, regex, sub)<a class="headerlink" href="#regsuball-str-regex-sub" title="Permalink to this headline">¶</a></h5>
<blockquote>
<div>As <code class="docutils literal notranslate"><span class="pre">regsub()</span></code>, but this replaces all occurrences.</div></blockquote>
<p>For converting or casting VCL values between data types use the functions
available in the std VMOD.</p>
</div>
</div>
</div>
<div class="section" id="versioning">
<h3>Versioning<a class="headerlink" href="#versioning" title="Permalink to this headline">¶</a></h3>
<p>Multiple versions of the VCL syntax can coexist within certain
constraints.</p>
<p>The VCL syntax version at the start of VCL file specified with <code class="docutils literal notranslate"><span class="pre">-f</span></code>
sets the hard limit that cannot be exceeded anywhere, and it selects
the appropriate version of the builtin VCL.</p>
<p>That means that you can never include <code class="docutils literal notranslate"><span class="pre">vcl</span> <span class="pre">9.1;</span></code> from <code class="docutils literal notranslate"><span class="pre">vcl</span> <span class="pre">8.7;</span></code>,
but the opposite <em>may</em> be possible, to the extent the compiler
supports it.</p>
<p>Files pulled in via <code class="docutils literal notranslate"><span class="pre">include</span></code> do not need to have a
<code class="docutils literal notranslate"><span class="pre">vcl</span></code> <em>X.Y</em><code class="docutils literal notranslate"><span class="pre">;</span></code> but it may be a good idea to do it anyway, to
not have surprises in the future. The syntax version set in an
included file only applies to that file and any files it includes -
unless these set their own VCL syntax version.</p>
<p>The version of Varnish this file belongs to supports syntax 4.0 only.</p>
</div>
<div class="section" id="examples">
<h3>EXAMPLES<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h3>
<p>For examples, please see the online documentation.</p>
</div>
<div class="section" id="see-also">
<h3>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li><a class="reference internal" href="varnishd.html#varnishd-1"><span class="std std-ref">varnishd</span></a></li>
<li><a class="reference internal" href="vmod_generated.html#vmod-directors-3"><span class="std std-ref">vmod_directors</span></a></li>
<li><a class="reference internal" href="vmod_generated.html#vmod-std-3"><span class="std std-ref">vmod_std</span></a></li>
</ul>
</div>
<div class="section" id="history">
<h3>HISTORY<a class="headerlink" href="#history" title="Permalink to this headline">¶</a></h3>
<p>VCL was developed by Poul-Henning Kamp in cooperation with Verdens
Gang AS, Redpill Linpro and Varnish Software. This manual page is
written by Per Buer, Poul-Henning Kamp, Martin Blix Grydeland,
Kristian Lyngstøl, Lasse Karstensen and possibly others.</p>
</div>
<div class="section" id="copyright">
<h3>COPYRIGHT<a class="headerlink" href="#copyright" title="Permalink to this headline">¶</a></h3>
<p>This document is licensed under the same license as Varnish
itself. See LICENSE for details.</p>
<ul class="simple">
<li>Copyright (c) 2006 Verdens Gang AS</li>
<li>Copyright (c) 2006-2015 Varnish Software AS</li>
</ul>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<h3><a href="../index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">VCL</a><ul>
<li><a class="reference internal" href="#varnish-configuration-language">Varnish Configuration Language</a><ul>
<li><a class="reference internal" href="#description">DESCRIPTION</a><ul>
<li><a class="reference internal" href="#operators">Operators</a></li>
<li><a class="reference internal" href="#conditionals">Conditionals</a></li>
<li><a class="reference internal" href="#strings-booleans-time-duration-integers-and-real-numbers">Strings, booleans, time, duration, integers and real numbers</a><ul>
<li><a class="reference internal" href="#strings">Strings</a></li>
<li><a class="reference internal" href="#booleans">Booleans</a></li>
<li><a class="reference internal" href="#time">Time</a></li>
<li><a class="reference internal" href="#durations">Durations</a></li>
<li><a class="reference internal" href="#integers">Integers</a></li>
<li><a class="reference internal" href="#real-numbers">Real numbers</a></li>
</ul>
</li>
<li><a class="reference internal" href="#regular-expressions">Regular Expressions</a></li>
<li><a class="reference internal" href="#include-statement">Include statement</a></li>
<li><a class="reference internal" href="#import-statement">Import statement</a></li>
<li><a class="reference internal" href="#comments">Comments</a></li>
<li><a class="reference internal" href="#backend-definition">Backend definition</a></li>
<li><a class="reference internal" href="#probes">Probes</a></li>
<li><a class="reference internal" href="#access-control-list-acl">Access Control List (ACL)</a></li>
<li><a class="reference internal" href="#vcl-objects">VCL objects</a></li>
<li><a class="reference internal" href="#subroutines">Subroutines</a><ul>
<li><a class="reference internal" href="#return-statements">Return statements</a></li>
<li><a class="reference internal" href="#multiple-subroutines">Multiple subroutines</a></li>
</ul>
</li>
<li><a class="reference internal" href="#vcl-variables">VCL Variables</a><ul>
<li><a class="reference internal" href="#local-server-remote-and-client">local, server, remote and client</a></li>
<li><a class="reference internal" href="#req-and-req-top">req and req_top</a></li>
<li><a class="reference internal" href="#bereq">bereq</a></li>
<li><a class="reference internal" href="#beresp">beresp</a></li>
<li><a class="reference internal" href="#obj">obj</a></li>
<li><a class="reference internal" href="#resp">resp</a></li>
<li><a class="reference internal" href="#special-variables">Special variables</a></li>
<li><a class="reference internal" href="#sess">sess</a></li>
<li><a class="reference internal" href="#storage">storage</a></li>
</ul>
</li>
<li><a class="reference internal" href="#functions">Functions</a><ul>
<li><a class="reference internal" href="#ban-string">ban(STRING)</a></li>
<li><a class="reference internal" href="#hash-data-input">hash_data(input)</a></li>
<li><a class="reference internal" href="#synthetic-string">synthetic(STRING)</a></li>
<li><a class="reference internal" href="#regsub-str-regex-sub">regsub(str, regex, sub)</a></li>
<li><a class="reference internal" href="#regsuball-str-regex-sub">regsuball(str, regex, sub)</a></li>
</ul>
</li>
</ul>
</li>
<li><a class="reference internal" href="#versioning">Versioning</a></li>
<li><a class="reference internal" href="#examples">EXAMPLES</a></li>
<li><a class="reference internal" href="#see-also">SEE ALSO</a></li>
<li><a class="reference internal" href="#history">HISTORY</a></li>
<li><a class="reference internal" href="#copyright">COPYRIGHT</a></li>
</ul>
</li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="index.html"
title="previous chapter">The Varnish Reference Manual</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="states.html"
title="next chapter">Varnish Processing States</a></p>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../_sources/reference/vcl.rst.txt"
rel="nofollow">Show Source</a></li>
</ul>
</div>
<div id="searchbox" style="display: none" role="search">
<h3>Quick search</h3>
<div class="searchformwrapper">
<form class="search" action="../search.html" method="get">
<input type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="states.html" title="Varnish Processing States"
>next</a> |</li>
<li class="right" >
<a href="index.html" title="The Varnish Reference Manual"
>previous</a> |</li>
<li class="nav-item nav-item-0"><a href="../index.html">Varnish version 6.0.3 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="index.html" >The Varnish Reference Manual</a> »</li>
</ul>
</div>
<div class="footer" role="contentinfo">
© Copyright 2010-2014, Varnish Software AS.
Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.7.6.
</div>
</body>
</html>