Enhanced PHP File Manager

⬆️ Go Up (..)

📊 Server Information

Server:

nginx/1.28.0

System:

Linux 6.8.0-90-generic

PHP Version:

8.4.15

User:

alqudsvolunteers

Directory:

/home/alqudsvolunteers/rootlink/proc/thread-self/root/usr/share/doc/varnish/html/users-guide

Free Space:

80.25 GB

🔧 Quick Actions

✏️ Editing: vcl-hashing.html

<!DOCTYPE html>

<title>Hashing &#8212; Varnish version 7.5.0 documentation</title>
    <link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=fa44fd50" />
    <link rel="stylesheet" type="text/css" href="../_static/classic.css?v=e2714048" />
    
    <script src="../_static/documentation_options.js?v=8214db13"></script>
    <script src="../_static/doctools.js?v=888ff710"></script>
    <script src="../_static/sphinx_highlight.js?v=dc90522c"></script>
    
    <link rel="index" title="Index" href="../genindex.html" />
    <link rel="search" title="Search" href="../search.html" />
    <link rel="next" title="Grace mode and keep" href="vcl-grace.html" />
    <link rel="prev" title="Backend servers" href="vcl-backends.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="vcl-grace.html" title="Grace mode and keep"
             accesskey="N">next</a> |</li>
        <li class="right" >
          <a href="vcl-backends.html" title="Backend servers"
             accesskey="P">previous</a> |</li>
        <li class="nav-item nav-item-0"><a href="../index.html">Varnish version 7.5.0 documentation</a> &#187;</li>
          <li class="nav-item nav-item-1"><a href="index.html" >The Varnish Users Guide</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="vcl.html" accesskey="U">VCL - Varnish Configuration Language</a> &#187;</li>
        <li class="nav-item nav-item-this"><a href="">Hashing</a></li> 
      </ul>
    </div>

<div class="document">
      <div class="documentwrapper">
        <div class="bodywrapper">
          <div class="body" role="main">
            
  <section id="hashing">
<h1>Hashing<a class="headerlink" href="#hashing" title="Link to this heading">¶</a></h1>
<p>Internally, when Varnish stores content in the cache indexed by a hash
key used to find the object again. In the default setup
this key is calculated based on <cite>URL</cite>, the <cite>Host:</cite> header, or
if there is none, the IP address of the server:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_hash</span> <span class="p">{</span>
    <span class="n">hash_data</span><span class="p">(</span><span class="n">req</span><span class="o">.</span><span class="n">url</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="p">)</span> <span class="p">{</span>
        <span class="n">hash_data</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="p">}</span> <span class="k">else</span> <span class="p">{</span>
        <span class="n">hash_data</span><span class="p">(</span><span class="n">server</span><span class="o">.</span><span class="n">ip</span><span class="p">);</span>
    <span class="p">}</span>
    <span class="k">return</span> <span class="p">(</span><span class="n">lookup</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>As you can see it first hashes <cite>req.url</cite> and then <cite>req.http.host</cite> if
it exists. It is worth pointing out that Varnish doesn’t lowercase the
hostname or the URL before hashing it so in theory having “Varnish.org/”
and “varnish.org/” would result in different cache entries. Browsers
however, tend to lowercase hostnames.</p>
<p>You can change what goes into the hash. This way you can make Varnish
serve up different content to different clients based on arbitrary
criteria.</p>
<p>Let’s say you want to serve pages in different languages to your users
based on where their IP address is located. You would need some Vmod to
get a country code and then put it into the hash. It might look like this.</p>
<p>In <cite>vcl_recv</cite>:</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">X</span><span class="o">-</span><span class="n">Country</span><span class="o">-</span><span class="n">Code</span> <span class="o">=</span> <span class="n">geoip</span><span class="o">.</span><span class="n">lookup</span><span class="p">(</span><span class="n">client</span><span class="o">.</span><span class="n">ip</span><span class="p">);</span>
</pre></div>
</div>
<p>And then add a <cite>vcl_hash</cite>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_hash</span> <span class="p">{</span>
    <span class="n">hash_data</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">X</span><span class="o">-</span><span class="n">Country</span><span class="o">-</span><span class="n">Code</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Because there is no <cite>return(lookup)</cite>, the builtin VCL will take care
of adding the URL, <cite>Host:</cite> or server IP# to the hash as usual.</p>
<p>If <cite>vcl_hash</cite> did return, ie:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sub</span> <span class="n">vcl_hash</span> <span class="p">{</span>
    <span class="n">hash_data</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">X</span><span class="o">-</span><span class="n">Country</span><span class="o">-</span><span class="n">Code</span><span class="p">);</span>
    <span class="k">return</span><span class="p">(</span><span class="n">lookup</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>then <em>only</em> the country-code would matter, and Varnish would return
seemingly random objects, ignoring the URL, (but they would always
have the correct <cite>X-Country-Code</cite>).</p>
</section>

<div class="clearer"></div>
          </div>
        </div>
      </div>
      <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
        <div class="sphinxsidebarwrapper">
  <div>
    <h4>Previous topic</h4>
    <p class="topless"><a href="vcl-backends.html"
                          title="previous chapter">Backend servers</a></p>
  </div>
  <div>
    <h4>Next topic</h4>
    <p class="topless"><a href="vcl-grace.html"
                          title="next chapter">Grace mode and keep</a></p>
  </div>
  <div role="note" aria-label="source link">
    <h3>This Page</h3>
    <ul class="this-page-menu">
      <li><a href="../_sources/users-guide/vcl-hashing.rst.txt"
            rel="nofollow">Show Source</a></li>
    </ul>
   </div>
<div id="searchbox" style="display: none" role="search">
  <h3 id="searchlabel">Quick search</h3>
    <div class="searchformwrapper">
    <form class="search" action="../search.html" method="get">
      <input type="text" name="q" aria-labelledby="searchlabel" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"/>
      <input type="submit" value="Go" />
    </form>
    </div>
</div>
<script>document.getElementById('searchbox').style.display = "block"</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="vcl-grace.html" title="Grace mode and keep"
             >next</a> |</li>
        <li class="right" >
          <a href="vcl-backends.html" title="Backend servers"
             >previous</a> |</li>
        <li class="nav-item nav-item-0"><a href="../index.html">Varnish version 7.5.0 documentation</a> &#187;</li>
          <li class="nav-item nav-item-1"><a href="index.html" >The Varnish Users Guide</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="vcl.html" >VCL - Varnish Configuration Language</a> &#187;</li>
        <li class="nav-item nav-item-this"><a href="">Hashing</a></li> 
      </ul>
    </div>
    <div class="footer" role="contentinfo">
    &#169; Copyright 2010-2014, Varnish Software AS.
      Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 7.2.6.
    </div>
  </body>
</html>

❌ Cancel

🗂️ Enhanced PHP File Manager

📊 Server Information

🔧 Quick Actions

✏️ Editing: vcl-hashing.html

📤 Upload File

📁 Create Folder

📄 Create File

✏️ Rename Item

🗑️ Delete Confirmation