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<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Changes in Varnish 5.0 — Varnish version 7.1.1 documentation</title> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <link rel="stylesheet" href="../_static/classic.css" type="text/css" /> <script id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script src="../_static/jquery.js"></script> <script src="../_static/underscore.js"></script> <script 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="Upgrading to Varnish 5.0" href="upgrading-5.0.html" /> <link rel="prev" title="Varnish 5.0 Release Note" href="relnote-5.0.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="upgrading-5.0.html" title="Upgrading to Varnish 5.0" accesskey="N">next</a> |</li> <li class="right" > <a href="relnote-5.0.html" title="Varnish 5.0 Release Note" accesskey="P">previous</a> |</li> <li class="nav-item nav-item-0"><a href="../index.html">Varnish version 7.1.1 documentation</a> »</li> <li class="nav-item nav-item-1"><a href="index.html" accesskey="U">What’s new / Upgrading</a> »</li> <li class="nav-item nav-item-this"><a href="">Changes in Varnish 5.0</a></li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="changes-in-varnish-5-0"> <span id="whatsnew-changes-5-0"></span><h1>Changes in Varnish 5.0<a class="headerlink" href="#changes-in-varnish-5-0" title="Permalink to this headline">¶</a></h1> <p>Varnish 5.0 changes some (mostly) internal APIs and adds some major new features over Varnish 4.1.</p> <div class="section" id="separate-vcl-files-and-vcl-labels"> <h2>Separate VCL files and VCL labels<a class="headerlink" href="#separate-vcl-files-and-vcl-labels" title="Permalink to this headline">¶</a></h2> <p>Varnish 5.0 supports jumping from the active VCL’s <code class="docutils literal notranslate"><span class="pre">vcl_recv{}</span></code> to another VCL via a VCL label.</p> <p>The major use of this will probably be to have a separate VCL for each domain/vhost, in order to untangle complex VCL files, but it is not limited to this criteria, it would also be possible to send all POSTs, all JPEG images or all traffic from a certain IP range to a separate VCL file.</p> <p>VCL labels can also be used to give symbolic names to loaded VCL configurations, so that operations personnel only need to know about “normal”, “weekend” and “emergency”, and web developers can update these as usual, without having to tell ops what the new weekend VCL is called.</p> </div> <div class="section" id="very-experimental-http-2-support"> <h2>Very Experimental HTTP/2 support<a class="headerlink" href="#very-experimental-http-2-support" title="Permalink to this headline">¶</a></h2> <p>We are in the process of adding HTTP/2 support to Varnish, but the code is very green still - life happened.</p> <p>But you can actually get a bit of traffic though it already, and we hope to have it production ready for the next major release (2017-03-15).</p> <p>Varnish supports HTTP/1 -> 2 upgrade. For political reasons, no browsers support that, but tools like curl does.</p> <p>For encrypted HTTP/2 traffic, put a SSL proxy in front of Varnish.</p> <p>HTTP/2 support is disabled by default, to enable, set the <code class="docutils literal notranslate"><span class="pre">http2</span></code> feature bit.</p> </div> <div class="section" id="the-shard-director"> <h2>The Shard Director<a class="headerlink" href="#the-shard-director" title="Permalink to this headline">¶</a></h2> <p>We have added to the directors VMOD an overhauled version of a director which was available as an out-of-tree VMOD under the name VSLP for a couple of years: It’s basically a better hash director, which uses consistent hashing to provide improved stability of backend node selection when the configuration and/or health state of backends changes. There are several options to provide the shard key. The rampup feature allows to take just-gone-healthy backends in production smoothly, while the prewarm feature allows to prepare backends for traffic which they would see if the primary backend for a certain key went down.</p> <p>It can be reconfigured dynamically (outside <code class="docutils literal notranslate"><span class="pre">vcl_init{}</span></code>), but different to our other directors, configuration is transactional: Any series of backend changes must be concluded by a reconfigure call for activation.</p> </div> <div class="section" id="hit-for-pass-is-now-actually-hit-for-miss"> <h2>Hit-For-Pass is now actually Hit-For-Miss<a class="headerlink" href="#hit-for-pass-is-now-actually-hit-for-miss" title="Permalink to this headline">¶</a></h2> <p>Almost since the beginning of time (2008), varnish has hit-for-pass: It is basically a negative caching feature, putting into the cache objects as markers saying “when you hit this, your request should be a pass”. The purpose is to selectively avoid the request coalescing (waitinglist) feature, which is useful for cacheable content, but not for uncacheable objects. If we did not have hit-for-pass, without additional configuration in vcl_recv, requests to uncacheable content would be sent to the backend serialized (one after the other).</p> <p>As useful as this feature is, it has caused a lot of headaches to varnish administrators along the lines of “why the <em>beep</em> doesn’t Varnish cache this”: A hit-for-pass object stayed in cache for however long its ttl dictated and prevented caching whenever it got hit (“for that url” in most cases). In particular, as a pass object can not be turned into something cacheable retrospectively (<code class="docutils literal notranslate"><span class="pre">beresp.uncacheable</span></code> can be changed from <code class="docutils literal notranslate"><span class="pre">false</span></code> to <code class="docutils literal notranslate"><span class="pre">true</span></code>, but not the other way around), even responses which would have been cacheable were not cached. So, when a hit-for-pass object got into cache unintentionally, it had to be removed explicitly (using a ban or purge).</p> <p>We’ve changed this now:</p> <p>A hit-for-pass object (we still call it like this in the docs, logging and statistics) will now cause a cache-miss for all subsequent requests, so if any backend response qualifies for caching, it will get cached and subsequent requests will be hits.</p> <p>In short: We’ve changed from “the uncacheable case wins” to “the cacheable case wins” or from hit-for-pass to hit-for-miss.</p> <p>The primary consequence which we are aware of at the time of this release is caused be the fact that, to create cacheable objects, we need to make backend requests unconditional (that is, remove the <code class="docutils literal notranslate"><span class="pre">If-Modified-Since</span></code> and <code class="docutils literal notranslate"><span class="pre">If-None-Match</span> <span class="pre">headers</span></code>): For conditional client requests on hit-for-pass objects, Varnish will now issue an unconditional backend fetch and, for 200 responses, send a 304 or 200 response to the client as appropriate.</p> <p>As of the time of this release we cannot say if this will remain the final word on this topic, but we hope that it will mean an improvement for most users of Varnish.</p> </div> <div class="section" id="ban-lurker-improvements"> <h2>Ban Lurker Improvements<a class="headerlink" href="#ban-lurker-improvements" title="Permalink to this headline">¶</a></h2> <p>We have made the ban lurker even more efficient by example of some real live situations with tens of thousands of bans using inefficient regular expressions.</p> <p>The new parameter <code class="docutils literal notranslate"><span class="pre">ban_lurker_holdoff</span></code> tells the ban lurker for how long it should get out of the way when it could potentially slow down lookups due to lock contention. Previously this was the same as <code class="docutils literal notranslate"><span class="pre">ban_lurker_sleep</span></code>.</p> </div> <div class="section" id="request-body-sent-always-cacheable-post"> <span id="whatsnew-changes-5-0-reqbody"></span><h2>Request Body sent always / “cacheable POST”<a class="headerlink" href="#request-body-sent-always-cacheable-post" title="Permalink to this headline">¶</a></h2> <p>Previously, we would only send a request body for passed requests (and for pipe mode, but this is special anyway and should be avoided).</p> <p>Not so any more, but the default behaviour has not changed:</p> <p>Whenever a request has a body, it will get sent to the backend for a cache miss (and pass, as before). This can be prevented by an <code class="docutils literal notranslate"><span class="pre">unset</span> <span class="pre">bereq.body</span></code> and the <code class="docutils literal notranslate"><span class="pre">builtin.vcl</span></code> removes the body for GET requests because it is questionable if GET with a body is valid anyway (but some applications use it).</p> <p>So the often-requested ability to cache POST/PATCH/… is now available, but not out-of-the-box:</p> <ul class="simple"> <li><p>The <code class="docutils literal notranslate"><span class="pre">builtin.vcl</span></code> still contains a <code class="docutils literal notranslate"><span class="pre">return(pass)</span></code> for anything but a GET or HEAD because other HTTP methods, by definition, may cause state changes / side effects on backends. The application at hand should be understood well before caching of non-GET/non-HEAD is considered.</p></li> <li><p>For misses, core code still calls the equivalent of <code class="docutils literal notranslate"><span class="pre">set</span> <span class="pre">bereq.method</span> <span class="pre">=</span> <span class="pre">"GET"</span></code> before calling <code class="docutils literal notranslate"><span class="pre">vcl_backend_fetch</span></code>, so to make a backend request with the original request method, it needs to be saved in <code class="docutils literal notranslate"><span class="pre">vcl_recv</span></code> and restored in <code class="docutils literal notranslate"><span class="pre">vcl_backend_fetch</span></code>.</p></li> <li><p>Care should be taken to choose an appropriate cache key and/or Vary criteria. Adding the request body to the cache key is not possible with core varnish, but through a VMOD <a class="reference external" href="https://github.com/aondio/libvmod-bodyaccess">https://github.com/aondio/libvmod-bodyaccess</a></p></li> </ul> <p>To summarize: You should know what you are doing when caching anything but a GET or HEAD and without creating an appropriate cache key doing so is almost guaranteed to be wrong.</p> </div> <div class="section" id="esi-and-backend-request-coalescing-waitinglist-improvement"> <h2>ESI and Backend Request Coalescing (“waitinglist”) Improvement<a class="headerlink" href="#esi-and-backend-request-coalescing-waitinglist-improvement" title="Permalink to this headline">¶</a></h2> <p>Previously, ESI subrequests depending on objects being fetched from the backed used polling, which typically added some ~5ms of processing time to such subrequests and could lead to starvation effects in extreme corner cases.</p> <p>The waitinglist logic for ESI subrequests now uses condition variables to trigger immediate continuation of ESI processing when an object being waited for becomes available.</p> </div> <div class="section" id="backend-proxy-protocol-requests"> <h2>Backend PROXY protocol requests<a class="headerlink" href="#backend-proxy-protocol-requests" title="Permalink to this headline">¶</a></h2> <p>Are now supported through the <code class="docutils literal notranslate"><span class="pre">.proxy_header</span></code> attribute of the backend definition.</p> </div> <div class="section" id="default-vcl-search-path"> <h2>Default VCL search path<a class="headerlink" href="#default-vcl-search-path" title="Permalink to this headline">¶</a></h2> <p>For default builds, vcl files are now also being looked for under <code class="docutils literal notranslate"><span class="pre">/usr/share/varnish/vcl</span></code> if not found in <code class="docutils literal notranslate"><span class="pre">/etc/varnish</span></code>.</p> <p>For custom builds, the actual search path is <code class="docutils literal notranslate"><span class="pre">${varnishconfdir}:${datarootdir}/varnish/vcl</span></code></p> </div> <div class="section" id="devicedetect-vcl"> <h2>devicedetect.vcl<a class="headerlink" href="#devicedetect-vcl" title="Permalink to this headline">¶</a></h2> <p>The basic device detection vcl is now bundled with varnish.</p> </div> <div class="section" id="varnishtest"> <h2>varnishtest<a class="headerlink" href="#varnishtest" title="Permalink to this headline">¶</a></h2> <ul class="simple"> <li><p><code class="docutils literal notranslate"><span class="pre">resp.msg</span></code> renamed to <code class="docutils literal notranslate"><span class="pre">resp.reason</span></code> for consistency with vcl</p></li> <li><p>HTTP2 testing capabilities added</p></li> <li><p>default search path for executables and vmods added</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">sema</span></code> mechanism replaced by <code class="docutils literal notranslate"><span class="pre">barrier</span></code></p></li> <li><p>support for PROXY requests</p></li> </ul> </div> <div class="section" id="misc"> <h2>misc<a class="headerlink" href="#misc" title="Permalink to this headline">¶</a></h2> <p>Brief notes on other changes</p> <ul class="simple"> <li><p>Added separate thread for object expiry</p></li> <li><p>The ESI parser is now more tolerant to some syntactic corner cases</p></li> <li><p>Reduced needless rushing of requests on the waitinglist</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">varnishhist</span></code> can now process backend requests and offers a timebend function to control the processing speed</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">std.integer()</span></code> can now also parse real numbers and truncates them</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">std.log()</span></code> now also works correctly during <code class="docutils literal notranslate"><span class="pre">vcl_init{}</span></code></p></li> <li><p>further improved stability when handling workspace overflows</p></li> <li><p>numerous vcl compiler improvements</p></li> </ul> </div> <div class="section" id="news-for-vmod-authors"> <h2>News for VMOD authors<a class="headerlink" href="#news-for-vmod-authors" title="Permalink to this headline">¶</a></h2> <ul class="simple"> <li><p>It is now mandatory to have a description in the <code class="docutils literal notranslate"><span class="pre">$Module</span></code> line of a <code class="docutils literal notranslate"><span class="pre">vcc</span></code> file.</p></li> <li><p>vcl cli events (in particular, <code class="docutils literal notranslate"><span class="pre">vcl_init{}</span></code> /<code class="docutils literal notranslate"><span class="pre">vcl_fini{}</span></code>) now have a workspace and <code class="docutils literal notranslate"><span class="pre">PRIV_TASK</span></code> available for VMODs.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">PRIV_*</span></code> now also work for object methods with unchanged scope. In particular, they are per VMOD and <cite>not</cite> per object - e.g. the same <code class="docutils literal notranslate"><span class="pre">PRIV_TASK</span></code> gets passed to object methods as to functions during a VCL task.</p></li> <li><p>varnish now provides a random number api, see vrnd.h</p></li> <li><p>vbm (variable size bitmaps) improved</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">vmodtool.py</span></code> for translating vcc files has been largely rewritten, there may still exist regressions which remained unnoticed</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">vmodtool.py</span></code> now requires at least Python 2.6</p></li> <li><p>New autoconf macros are available, they should greatly simplify build systems of out-of-tree VMODs. They are implemented and documented in <code class="docutils literal notranslate"><span class="pre">varnish.m4</span></code>, and the previous macros now live in <code class="docutils literal notranslate"><span class="pre">varnish-legacy.m4</span></code> so existing VMODs should still build fine.</p></li> </ul> </div> </div> <div class="clearer"></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="#">Changes in Varnish 5.0</a><ul> <li><a class="reference internal" href="#separate-vcl-files-and-vcl-labels">Separate VCL files and VCL labels</a></li> <li><a class="reference internal" href="#very-experimental-http-2-support">Very Experimental HTTP/2 support</a></li> <li><a class="reference internal" href="#the-shard-director">The Shard Director</a></li> <li><a class="reference internal" href="#hit-for-pass-is-now-actually-hit-for-miss">Hit-For-Pass is now actually Hit-For-Miss</a></li> <li><a class="reference internal" href="#ban-lurker-improvements">Ban Lurker Improvements</a></li> <li><a class="reference internal" href="#request-body-sent-always-cacheable-post">Request Body sent always / “cacheable POST”</a></li> <li><a class="reference internal" href="#esi-and-backend-request-coalescing-waitinglist-improvement">ESI and Backend Request Coalescing (“waitinglist”) Improvement</a></li> <li><a class="reference internal" href="#backend-proxy-protocol-requests">Backend PROXY protocol requests</a></li> <li><a class="reference internal" href="#default-vcl-search-path">Default VCL search path</a></li> <li><a class="reference internal" href="#devicedetect-vcl">devicedetect.vcl</a></li> <li><a class="reference internal" href="#varnishtest">varnishtest</a></li> <li><a class="reference internal" href="#misc">misc</a></li> <li><a class="reference internal" href="#news-for-vmod-authors">News for VMOD authors</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="relnote-5.0.html" title="previous chapter">Varnish 5.0 Release Note</a></p> <h4>Next topic</h4> <p class="topless"><a href="upgrading-5.0.html" title="next chapter">Upgrading to Varnish 5.0</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../_sources/whats-new/changes-5.0.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" /> <input type="submit" value="Go" /> </form> </div> </div> <script>$('#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="upgrading-5.0.html" title="Upgrading to Varnish 5.0" >next</a> |</li> <li class="right" > <a href="relnote-5.0.html" title="Varnish 5.0 Release Note" >previous</a> |</li> <li class="nav-item nav-item-0"><a href="../index.html">Varnish version 7.1.1 documentation</a> »</li> <li class="nav-item nav-item-1"><a href="index.html" >What’s new / Upgrading</a> »</li> <li class="nav-item nav-item-this"><a href="">Changes in Varnish 5.0</a></li> </ul> </div> <div class="footer" role="contentinfo"> © Copyright 2010-2014, Varnish Software AS. 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