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<div class="section" id="separate-vcl-files">
<span id="users-guide-separate-vcl"></span><h1>Separate VCL files<a class="headerlink" href="#separate-vcl-files" title="Permalink to this headline">¶</a></h1>
<p>Having multiple different vhosts in the same Varnish is a very
typical use-case, and from Varnish 5.0 it is possible to have
a separate VCL files for separate vhosts or any other distinct
subset of requests.</p>
<p>Assume that we want to handle <code class="docutils literal notranslate"><span class="pre">varnish.org</span></code> with one VCL file
and <code class="docutils literal notranslate"><span class="pre">varnish-cache.org</span></code> with another VCL file.</p>
<p>First load the two VCL files:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">vcl</span><span class="o">.</span><span class="n">load</span> <span class="n">vo_1</span> <span class="o">/</span><span class="n">somewhere</span><span class="o">/</span><span class="n">vo</span><span class="o">.</span><span class="n">vcl</span>
<span class="n">vcl</span><span class="o">.</span><span class="n">load</span> <span class="n">vc_1</span> <span class="o">/</span><span class="n">somewhere</span><span class="o">/</span><span class="n">vc</span><span class="o">.</span><span class="n">vcl</span>
</pre></div>
</div>
<p>These are 100% normal VCL files, as they would look if you ran
only that single domain on your varnish instance.</p>
<p>Next we need to point VCL labels to them:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">vcl</span><span class="o">.</span><span class="n">label</span> <span class="n">l_vo</span> <span class="n">vo_1</span>
<span class="n">vcl</span><span class="o">.</span><span class="n">label</span> <span class="n">l_vc</span> <span class="n">vc_1</span>
</pre></div>
</div>
<p>Next we write the top-level VCL program, which branches out
to the other two, depending on the Host: header in the
request:</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="c1"># We have to have a backend, even if we do not use it</span>
<span class="n">backend</span> <span class="n">default</span> <span class="p">{</span> <span class="o">.</span><span class="n">host</span> <span class="o">=</span> <span class="s2">"127.0.0.1"</span><span class="p">;</span> <span class="p">}</span>
<span class="n">sub</span> <span class="n">vcl_recv</span> <span class="p">{</span>
<span class="c1"># Normalize host header</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">host</span> <span class="o">=</span> <span class="n">std</span><span class="o">.</span><span class="n">tolower</span><span class="p">(</span><span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">host</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">host</span> <span class="o">~</span> <span class="s2">"\.?varnish\.org$"</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="p">(</span><span class="n">vcl</span><span class="p">(</span><span class="n">l_vo</span><span class="p">));</span>
<span class="p">}</span>
<span class="k">if</span> <span class="p">(</span><span class="n">req</span><span class="o">.</span><span class="n">http</span><span class="o">.</span><span class="n">host</span> <span class="o">~</span> <span class="s2">"\.?varnish-cache\.org$"</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="p">(</span><span class="n">vcl</span><span class="p">(</span><span class="n">l_vc</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">302</span><span class="p">,</span> <span class="s2">"http://varnish-cache.org"</span><span class="p">));</span>
<span class="p">}</span>
<span class="n">sub</span> <span class="n">vcl_synth</span> <span class="p">{</span>
<span class="k">if</span> <span class="p">(</span><span class="n">resp</span><span class="o">.</span><span class="n">status</span> <span class="o">==</span> <span class="mi">301</span> <span class="o">||</span> <span class="n">resp</span><span class="o">.</span><span class="n">status</span> <span class="o">==</span> <span class="mi">302</span><span class="p">)</span> <span class="p">{</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">location</span> <span class="o">=</span> <span class="n">resp</span><span class="o">.</span><span class="n">reason</span><span class="p">;</span>
<span class="nb">set</span> <span class="n">resp</span><span class="o">.</span><span class="n">reason</span> <span class="o">=</span> <span class="s2">"Moved"</span><span class="p">;</span>
<span class="k">return</span> <span class="p">(</span><span class="n">deliver</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Finally, we load the top level VCL and make it the
active VCL:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">vcl</span><span class="o">.</span><span class="n">load</span> <span class="n">top_1</span> <span class="o">/</span><span class="n">somewhere</span><span class="o">/</span><span class="n">top</span><span class="o">.</span><span class="n">vcl</span>
<span class="n">vcl</span><span class="o">.</span><span class="n">use</span> <span class="n">top_1</span>
</pre></div>
</div>
<p>If you want to update one of the separated VCLs, you load the new
one and change the label to point to it:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">vcl</span><span class="o">.</span><span class="n">load</span> <span class="n">vo_2</span> <span class="o">/</span><span class="n">somewhere</span><span class="o">/</span><span class="n">vo</span><span class="o">.</span><span class="n">vcl</span>
<span class="n">vcl</span><span class="o">.</span><span class="n">label</span> <span class="n">l_vo</span> <span class="n">vo_2</span>
</pre></div>
</div>
<p>If you want to change the top level VCL, do as you always did:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">vcl</span><span class="o">.</span><span class="n">load</span> <span class="n">top_2</span> <span class="o">/</span><span class="n">somewhere</span><span class="o">/</span><span class="n">top</span><span class="o">.</span><span class="n">vcl</span>
<span class="n">vcl</span><span class="o">.</span><span class="n">use</span> <span class="n">top_2</span>
</pre></div>
</div>
<div class="section" id="details-details-details">
<h2>Details, details, details:<a class="headerlink" href="#details-details-details" title="Permalink to this headline">¶</a></h2>
<ul class="simple">
<li>All requests <em>always</em> start in the active VCL - the one from <code class="docutils literal notranslate"><span class="pre">vcl.use</span></code></li>
<li>Only VCL labels can be used in <code class="docutils literal notranslate"><span class="pre">return(vcl(name))</span></code>. Without this
restriction the top level VCL would have to be reloaded every time
one of the separate VCLs were changed.</li>
<li>You can only switch VCLs from the active VCL. If you try it from one of
the separate VCLs, you will get a 503</li>
<li>You cannot remove VCL labels (with <code class="docutils literal notranslate"><span class="pre">vcl.discard</span></code>) if any VCL
contains <code class="docutils literal notranslate"><span class="pre">return(vcl(name_of_that_label))</span></code></li>
<li>You cannot remove VCLs which have a label attached to them.</li>
<li>This code is tested in testcase c00077</li>
<li>This is a very new feature, it may change</li>
<li>We would very much like feedback how this works for you</li>
</ul>
</div>
</div>
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<li><a class="reference internal" href="#">Separate VCL files</a><ul>
<li><a class="reference internal" href="#details-details-details">Details, details, details:</a></li>
</ul>
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