<!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="Content-Type" content="text/html; charset=utf-8" /> <title>Introduction — Buildbot 0.8.8 documentation</title> <link rel="stylesheet" href="../_static/agogo.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '0.8.8', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </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="shortcut icon" href="../_static/buildbot.ico"/> <link rel="top" title="Buildbot 0.8.8 documentation" href="../index.html" /> <link rel="up" title="Buildbot Manual" href="index.html" /> <link rel="next" title="Installation" href="installation.html" /> <link rel="prev" title="Buildbot Manual" href="index.html" /> </head> <body> <div class="header-wrapper"> <div class="header"> <p class="logo"><a href="../index.html"> <img class="logo" src="../_static/header-text-transparent.png" alt="Logo"/> </a></p> <div class="headertitle"><a href="../index.html">Buildbot 0.8.8 documentation</a></div> <div class="rel"> <a href="index.html" title="Buildbot Manual" accesskey="P">previous</a> | <a href="installation.html" title="Installation" accesskey="N">next</a> | <a href="../py-modindex.html" title="Python Module Index" >modules</a> | <a href="../genindex.html" title="General Index" accesskey="I">index</a> </div> </div> </div> <div class="content-wrapper"> <div class="content"> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="introduction"> <span id="id1"></span><h1>Introduction<a class="headerlink" href="#introduction" title="Permalink to this headline">¶</a></h1> <p>BuildBot is a system to automate the compile/test cycle required by most software projects to validate code changes. By automatically rebuilding and testing the tree each time something has changed, build problems are pinpointed quickly, before other developers are inconvenienced by the failure. The guilty developer can be identified and harassed without human intervention. By running the builds on a variety of platforms, developers who do not have the facilities to test their changes everywhere before checkin will at least know shortly afterwards whether they have broken the build or not. Warning counts, lint checks, image size, compile time, and other build parameters can be tracked over time, are more visible, and are therefore easier to improve.</p> <p>The overall goal is to reduce tree breakage and provide a platform to run tests or code-quality checks that are too annoying or pedantic for any human to waste their time with. Developers get immediate (and potentially public) feedback about their changes, encouraging them to be more careful about testing before checkin.</p> <p>Features:</p> <ul class="simple"> <li>run builds on a variety of slave platforms</li> <li>arbitrary build process: handles projects using C, Python, whatever</li> <li>minimal host requirements: Python and Twisted</li> <li>slaves can be behind a firewall if they can still do checkout</li> <li>status delivery through web page, email, IRC, other protocols</li> <li>track builds in progress, provide estimated completion time</li> <li>flexible configuration by subclassing generic build process classes</li> <li>debug tools to force a new build, submit fake <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s, query slave status</li> <li>released under the <a class="reference external" href="http://opensource.org/licenses/gpl-2.0.php">GPL</a></li> </ul> <div class="section" id="history-and-philosophy"> <span id="id2"></span><h2>History and Philosophy<a class="headerlink" href="#history-and-philosophy" title="Permalink to this headline">¶</a></h2> <p>The Buildbot was inspired by a similar project built for a development team writing a cross-platform embedded system. The various components of the project were supposed to compile and run on several flavors of unix (linux, solaris, BSD), but individual developers had their own preferences and tended to stick to a single platform. From time to time, incompatibilities would sneak in (some unix platforms want to use <tt class="file docutils literal"><span class="pre">string.h</span></tt>, some prefer <tt class="file docutils literal"><span class="pre">strings.h</span></tt>), and then the tree would compile for some developers but not others. The buildbot was written to automate the human process of walking into the office, updating a tree, compiling (and discovering the breakage), finding the developer at fault, and complaining to them about the problem they had introduced. With multiple platforms it was difficult for developers to do the right thing (compile their potential change on all platforms); the buildbot offered a way to help.</p> <p>Another problem was when programmers would change the behavior of a library without warning its users, or change internal aspects that other code was (unfortunately) depending upon. Adding unit tests to the codebase helps here: if an application's unit tests pass despite changes in the libraries it uses, you can have more confidence that the library changes haven't broken anything. Many developers complained that the unit tests were inconvenient or took too long to run: having the buildbot run them reduces the developer's workload to a minimum.</p> <p>In general, having more visibility into the project is always good, and automation makes it easier for developers to do the right thing. When everyone can see the status of the project, developers are encouraged to keep the tree in good working order. Unit tests that aren't run on a regular basis tend to suffer from bitrot just like code does: exercising them on a regular basis helps to keep them functioning and useful.</p> <p>The current version of the Buildbot is additionally targeted at distributed free-software projects, where resources and platforms are only available when provided by interested volunteers. The buildslaves are designed to require an absolute minimum of configuration, reducing the effort a potential volunteer needs to expend to be able to contribute a new test environment to the project. The goal is for anyone who wishes that a given project would run on their favorite platform should be able to offer that project a buildslave, running on that platform, where they can verify that their portability code works, and keeps working.</p> </div> <div class="section" id="system-architecture"> <span id="id3"></span><h2>System Architecture<a class="headerlink" href="#system-architecture" title="Permalink to this headline">¶</a></h2> <p>The Buildbot consists of a single <em>buildmaster</em> and one or more <em>buildslaves</em>, connected in a star topology. The buildmaster makes all decisions about what, when, and how to build. It sends commands to be run on the build slaves, which simply execute the commands and return the results. (certain steps involve more local decision making, where the overhead of sending a lot of commands back and forth would be inappropriate, but in general the buildmaster is responsible for everything).</p> <p>The buildmaster is usually fed <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s by some sort of version control system (<a class="reference internal" href="cfg-changesources.html#change-sources"><em>Change Sources</em></a>), which may cause builds to be run. As the builds are performed, various status messages are produced, which are then sent to any registered <a class="reference internal" href="cfg-statustargets.html#status-targets"><em>Status Targets</em></a>.</p> <img alt="Overview Diagram" src="../_images/overview.svg" /><p>The buildmaster is configured and maintained by the <em>buildmaster admin</em>, who is generally the project team member responsible for build process issues. Each buildslave is maintained by a <em>buildslave admin</em>, who do not need to be quite as involved. Generally slaves are run by anyone who has an interest in seeing the project work well on their favorite platform.</p> <div class="section" id="buildslave-connections"> <span id="id4"></span><h3>BuildSlave Connections<a class="headerlink" href="#buildslave-connections" title="Permalink to this headline">¶</a></h3> <p>The buildslaves are typically run on a variety of separate machines, at least one per platform of interest. These machines connect to the buildmaster over a TCP connection to a publically-visible port. As a result, the buildslaves can live behind a NAT box or similar firewalls, as long as they can get to buildmaster. The TCP connections are initiated by the buildslave and accepted by the buildmaster, but commands and results travel both ways within this connection. The buildmaster is always in charge, so all commands travel exclusively from the buildmaster to the buildslave.</p> <p>To perform builds, the buildslaves must typically obtain source code from a CVS/SVN/etc repository. Therefore they must also be able to reach the repository. The buildmaster provides instructions for performing builds, but does not provide the source code itself.</p> <img alt="BuildSlave Connections" src="../_images/slaves.svg" /></div> <div class="section" id="buildmaster-architecture"> <span id="id5"></span><h3>Buildmaster Architecture<a class="headerlink" href="#buildmaster-architecture" title="Permalink to this headline">¶</a></h3> <p>The buildmaster consists of several pieces:</p> <img alt="Buildmaster Architecture" src="../_images/master.svg" /><dl class="docutils"> <dt>Change Sources</dt> <dd>Which create a Change object each time something is modified in the VC repository. Most <tt class="xref py py-class docutils literal"><span class="pre">ChangeSource</span></tt>s listen for messages from a hook script of some sort. Some sources actively poll the repository on a regular basis. All <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s are fed to the <tt class="xref py py-class docutils literal"><span class="pre">Scheduler</span></tt>s.</dd> <dt>Schedulers</dt> <dd>Which decide when builds should be performed. They collect <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s into <tt class="xref py py-class docutils literal"><span class="pre">BuildRequest</span></tt>s, which are then queued for delivery to <tt class="xref py py-class docutils literal"><span class="pre">Builders</span></tt> until a buildslave is available.</dd> <dt>Builders</dt> <dd>Which control exactly <em>how</em> each build is performed (with a series of <tt class="xref py py-class docutils literal"><span class="pre">BuildStep</span></tt>s, configured in a <tt class="xref py py-class docutils literal"><span class="pre">BuildFactory</span></tt>). Each <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> is run on a single buildslave.</dd> <dt>Status plugins</dt> <dd>Which deliver information about the build results through protocols like HTTP, mail, and IRC.</dd> </dl> <p>Each <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt> is configured with a list of <tt class="xref py py-class docutils literal"><span class="pre">BuildSlave</span></tt>s that it will use for its builds. These buildslaves are expected to behave identically: the only reason to use multiple <tt class="xref py py-class docutils literal"><span class="pre">BuildSlave</span></tt>s for a single <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt> is to provide a measure of load-balancing.</p> <p>Within a single <tt class="xref py py-class docutils literal"><span class="pre">BuildSlave</span></tt>, each <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt> creates its own <tt class="xref py py-class docutils literal"><span class="pre">SlaveBuilder</span></tt> instance. These <tt class="xref py py-class docutils literal"><span class="pre">SlaveBuilder</span></tt>s operate independently from each other. Each gets its own base directory to work in. It is quite common to have many <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt>s sharing the same buildslave. For example, there might be two buildslaves: one for i386, and a second for PowerPC. There may then be a pair of <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt>s that do a full compile/test run, one for each architecture, and a lone <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt> that creates snapshot source tarballs if the full builders complete successfully. The full builders would each run on a single buildslave, whereas the tarball creation step might run on either buildslave (since the platform doesn't matter when creating source tarballs). In this case, the mapping would look like:</p> <div class="highlight-none"><div class="highlight"><pre>Builder(full-i386) -> BuildSlaves(slave-i386) Builder(full-ppc) -> BuildSlaves(slave-ppc) Builder(source-tarball) -> BuildSlaves(slave-i386, slave-ppc) </pre></div> </div> <p>and each <tt class="xref py py-class docutils literal"><span class="pre">BuildSlave</span></tt> would have two <tt class="xref py py-class docutils literal"><span class="pre">SlaveBuilders</span></tt> inside it, one for a full builder, and a second for the source-tarball builder.</p> <p>Once a <tt class="xref py py-class docutils literal"><span class="pre">SlaveBuilder</span></tt> is available, the <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt> pulls one or more <tt class="xref py py-class docutils literal"><span class="pre">BuildRequest</span></tt>s off its incoming queue. (It may pull more than one if it determines that it can merge the requests together; for example, there may be multiple requests to build the current <em>HEAD</em> revision). These requests are merged into a single <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> instance, which includes the <tt class="xref py py-class docutils literal"><span class="pre">SourceStamp</span></tt> that describes what exact version of the source code should be used for the build. The <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> is then randomly assigned to a free <tt class="xref py py-class docutils literal"><span class="pre">SlaveBuilder</span></tt> and the build begins.</p> <p>The behaviour when <tt class="xref py py-class docutils literal"><span class="pre">BuildRequest</span></tt>s are merged can be customized, <a class="reference internal" href="cfg-builders.html#merging-build-requests"><em>Merging Build Requests</em></a>.</p> </div> <div class="section" id="status-delivery-architecture"> <span id="id6"></span><h3>Status Delivery Architecture<a class="headerlink" href="#status-delivery-architecture" title="Permalink to this headline">¶</a></h3> <p>The buildmaster maintains a central <tt class="xref py py-class docutils literal"><span class="pre">Status</span></tt> object, to which various status plugins are connected. Through this <tt class="xref py py-class docutils literal"><span class="pre">Status</span></tt> object, a full hierarchy of build status objects can be obtained.</p> <img alt="Status Delivery" src="../_images/status.svg" /><p>The configuration file controls which status plugins are active. Each status plugin gets a reference to the top-level <tt class="xref py py-class docutils literal"><span class="pre">Status</span></tt> object. From there they can request information on each <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt>, <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>, <tt class="xref py py-class docutils literal"><span class="pre">Step</span></tt>, and <tt class="xref py py-class docutils literal"><span class="pre">LogFile</span></tt>. This query-on-demand interface is used by the <tt class="docutils literal"><span class="pre">html.Waterfall</span></tt> plugin to create the main status page each time a web browser hits the main URL.</p> <p>The status plugins can also subscribe to hear about new <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>s as they occur: this is used by the <tt class="xref py py-class docutils literal"><span class="pre">MailNotifier</span></tt> to create new email messages for each recently-completed <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>.</p> <p>The <tt class="xref py py-class docutils literal"><span class="pre">Status</span></tt> object records the status of old builds on disk in the buildmaster's base directory. This allows it to return information about historical builds.</p> <p>There are also status objects that correspond to <tt class="xref py py-class docutils literal"><span class="pre">Scheduler</span></tt>s and <tt class="xref py py-class docutils literal"><span class="pre">BuildSlave</span></tt>s. These allow status plugins to report information about upcoming builds, and the online/offline status of each buildslave.</p> </div> </div> <div class="section" id="control-flow"> <span id="id7"></span><h2>Control Flow<a class="headerlink" href="#control-flow" title="Permalink to this headline">¶</a></h2> <p>A day in the life of the buildbot:</p> <ul class="simple"> <li>A developer commits some source code changes to the repository. A hook script or commit trigger of some sort sends information about this change to the buildmaster through one of its configured Change Sources. This notification might arrive via email, or over a network connection (either initiated by the buildmaster as it <em>subscribes</em> to changes, or by the commit trigger as it pushes <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s towards the buildmaster). The <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt> contains information about who made the change, what files were modified, which revision contains the change, and any checkin comments.</li> <li>The buildmaster distributes this change to all of its configured <tt class="xref py py-class docutils literal"><span class="pre">Scheduler</span></tt>s. Any <tt class="docutils literal"><span class="pre">important</span></tt> changes cause the <tt class="docutils literal"><span class="pre">tree-stable-timer</span></tt> to be started, and the <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt> is added to a list of those that will go into a new <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>. When the timer expires, a <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> is started on each of a set of configured Builders, all compiling/testing the same source code. Unless configured otherwise, all <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>s run in parallel on the various buildslaves.</li> <li>The <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> consists of a series of <tt class="xref py py-class docutils literal"><span class="pre">Step</span></tt>s. Each <tt class="xref py py-class docutils literal"><span class="pre">Step</span></tt> causes some number of commands to be invoked on the remote buildslave associated with that <tt class="xref py py-class docutils literal"><span class="pre">Builder</span></tt>. The first step is almost always to perform a checkout of the appropriate revision from the same VC system that produced the <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>. The rest generally perform a compile and run unit tests. As each <tt class="xref py py-class docutils literal"><span class="pre">Step</span></tt> runs, the buildslave reports back command output and return status to the buildmaster.</li> <li>As the <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt> runs, status messages like "Build Started", "Step Started", "Build Finished", etc, are published to a collection of Status Targets. One of these targets is usually the HTML <tt class="docutils literal"><span class="pre">Waterfall</span></tt> display, which shows a chronological list of events, and summarizes the results of the most recent build at the top of each column. Developers can periodically check this page to see how their changes have fared. If they see red, they know that they've made a mistake and need to fix it. If they see green, they know that they've done their duty and don't need to worry about their change breaking anything.</li> <li>If a <tt class="xref py py-class docutils literal"><span class="pre">MailNotifier</span></tt> status target is active, the completion of a build will cause email to be sent to any developers whose <tt class="xref py py-class docutils literal"><span class="pre">Change</span></tt>s were incorporated into this <tt class="xref py py-class docutils literal"><span class="pre">Build</span></tt>. The <tt class="xref py py-class docutils literal"><span class="pre">MailNotifier</span></tt> can be configured to only send mail upon failing builds, or for builds which have just transitioned from passing to failing. Other status targets can provide similar real-time notification via different communication channels, like IRC.</li> </ul> </div> </div> </div> </div> </div> </div> <div class="sidebar"> <h3>Table Of Contents</h3> <ul class="current"> <li class="toctree-l1"><a class="reference internal" href="../tutorial/index.html">Buildbot Tutorial</a></li> <li class="toctree-l1 current"><a class="reference internal" href="index.html">Buildbot Manual</a><ul class="current"> <li class="toctree-l2 current"><a class="current reference internal" href="">Introduction</a><ul class="simple"> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="installation.html">Installation</a></li> <li class="toctree-l2"><a class="reference internal" href="concepts.html">Concepts</a></li> <li class="toctree-l2"><a class="reference internal" href="configuration.html">Configuration</a></li> <li class="toctree-l2"><a class="reference internal" href="customization.html">Customization</a></li> <li class="toctree-l2"><a class="reference internal" href="cmdline.html">Command-line Tool</a></li> <li class="toctree-l2"><a class="reference internal" href="resources.html">Resources</a></li> <li class="toctree-l2"><a class="reference internal" href="optimization.html">Optimization</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="../developer/index.html">Buildbot Development</a></li> <li class="toctree-l1"><a class="reference internal" href="../relnotes/index.html">Release Notes for Buildbot v0.8.8</a></li> </ul> <h3 style="margin-top: 1.5em;">Search</h3> <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> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <div class="clearer"></div> </div> </div> <div class="footer-wrapper"> <div class="footer"> <div class="left"> <a href="index.html" title="Buildbot Manual" >previous</a> | <a href="installation.html" title="Installation" >next</a> | <a href="../py-modindex.html" title="Python Module Index" >modules</a> | <a href="../genindex.html" title="General Index" >index</a> <br/> <a href="../_sources/manual/introduction.txt" rel="nofollow">Show Source</a> </div> <div class="right"> <div class="footer"> © Copyright Buildbot Team Members. 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