rfc:jenkins

Request for Comments: Continuous Integration via Jenkins

Introduction

The purpose of this RFC is to introduce the idea of using Jenkins for Continuous Integration in the PHP project supported with a Proof of concept implementation.

What is CI

Continuous Integration is a software development practice where members of a team integrate their work frequently, usually each person integrates at least daily - leading to multiple integrations per day. Each integration is verified by an automated build (including test) to detect integration errors as quickly as possible. Many teams find that this approach leads to significantly reduced integration problems and allows a team to develop cohesive software more rapidly. http://martinfowler.com/articles/continuousIntegration.html http://en.wikipedia.org/wiki/Continuous_integration

Why do we need CI?

  • Runs the build and the tests automatically, doesn't require human interaction to spot build and test failures.
  • Provides a solid baseline for others to check that they are seeing a problem or it is just some configuration problem on their end.
  • Provides an easy way to check the build status and the test results for different platform/environments (different cpu architectures, OS, etc.).
  • Allows us to follow the build trends and history, we can see the common defects, etc.

gcov.php.net

  • gcov.php.net is an in-house php application : http://svn.php.net/viewvc/web/php-gcov/trunk/
  • gcov.php.net does a thorough analysis (building the supported php versions and executing the testsuite with gcov, lcov and Valgrind for test coverage and memory leaks, and does some code checking.
  • gcov.php.net does a thorough analysis, but having to wait more than 2 days for a build result defeats the purpose of CI.
  • gcov.php.net only tests the code against one specific environment.
  • the development of gcov.php.net and the related work seems slowed/halted in the absence of Nuno Lopes.

Jenkins

Why Jenkins

  • It is a truly open source, no catch(MIT License https://github.com/jenkinsci/jenkins/blob/master/LICENSE.txt).
  • It has a active, open and committed community behind it.
  • It has an easy to extend architecture and there is a whole bunch of plugins (https://wiki.jenkins-ci.org/display/JENKINS/Plugins).
  • Supports distributed builds out of the box(https://wiki.jenkins-ci.org/display/JENKINS/Distributed+builds).
  • Supports both SVN, git and mercurial (and almost every other SCM), so the DVCS migration shouldn't cause any problem.
  • It is java based, so it is available on most platform without a major PITA.
  • Provides a web interface for both the administration/configuration and checking the build results.
  • Sebastian Bergmann prefers it over everything else. :)
  • Which means that currently it is one (if not the) most used CI tools in the php community.
  • The PEAR group also migrated to Jenkins (the migration was an independent project from this, but we are discussing to migrate the PEAR setup to ci.qa.php.net).

ci.qa.php.net

We have a demo/Proof of concept interface at http://ci.qa.php.net/

  • We have 4 virtual machines: 2 Linux(Debian Squeeze i386 and amd64) and 2 bsd(FreeBSD 8.2 i386 and amd64), the debian amd64 runs the jenkins master instance, and every vm(including the debian amd64) runs a jenkins slave.
  • We have 6 “matrix” job:
    • Two for each branch(5.3, 5.4, trunk):
      • the “build” job for building the binaries (./buildconf && ./configure –enable-debug && make)
      • the “test” job for running the testsuite against that branch
  • Each “build” job polls the svn repository periodically, triggers the build if any SCM changes occur for that branch and parses the build output for gcc warnings.
  • If the “build” job is successful, it will trigger the “test” job for that branch.
    • For showcasing the capabilities of running other php projects' testsuites against our builds, I created a job for Symfony2:
  • The “test” job will use the binary from the “build” job and execute the testsuite(which will generate the junit style test result), this job will fail if run-tests.php returns with a non-zero exit code(REPORT_EXIT_STATUS=1)
  • Both the “build” and the “test” job is a “matrix” job, also known as multi-configuration job:
    • The jenkins nodes can have labels, and the jobs can be attached to label(s), so they will only build on nodes having that label(s).
    • The multi configuration job means that the job will be executed multiple times, with slight variations in the build configuration.
    • Those variation could be many thing, but in our case, the axes of our matrix jobs are the labels: our builds will be executed on all four nodes.
    • By default, a matrix job is only considered successful, if all of the configuration jobs for that job succeeds.
    • Jenkins supports aggregating the test results from the configuration jobs, more on that later.
  • run-tests.php was patched to be able to generate ant junit compatible xml report which is supported by Jenkins(https://github.com/Tyrael/ci.qa.php.net/blob/master/run-tests.php).
    • This means that Jenkins can do advanced stuff with our test results, like
      • aggregating the results
      • showing the execution time for each test
      • groupping the test by status (passed, failed, error, skipped)
      • it can spot if a new test failure is introduced, etc.
  • I also created an ant build.xml for our jobs (https://github.com/Tyrael/ci.qa.php.net/blob/master/build.xml), so we can execute our build steps in more platform independent way.
  • There is an irc channel on freenode: #php.qa and we also set up an irc integration with jenkins (https://wiki.jenkins-ci.org/display/JENKINS/IRC+Plugin), so the build status can be followed/checked through irc.
  • Of course reporting via email is also supported and will be set up when needed.

Tutorial

  • http://ci.qa.php.net/ is the dashboard
    • it lists the projects and a quick summary about the status
      • S: status, the blue bubble means that the last execution for that particular job was a success, the red ball means failure(the yellow means unstable).
      • W: weather, the weather icons show a quick summary of the health of that job, sunny/cloudy/rain/thunder shows the frequency of build failures.
      • Job: job name
      • Last Success: Date of the last successful execution (and a link for that build)
      • Date of the last failed execution (and a link for that build)
      • Length of the last executon
      • Schedule a build (only accessible for authenticated users having the php-dev group membership, it doesn't use the svn user db or the karma system yet. :()
      • Cron Trigger: showing the scheduling for that particular job.
    • on the left there is the navigation:
      • Status: the status of the job, with the project matrix and some trends.
      • Changes: show which job execution was built from which scm revision.
      • Workspace: the current workspace (on the master node).
      • Schedule a build: same as on the dashboard.
      • Subversion polling log: output of the last scm poll.
    • and the Build history:
      • trend, see below
      • Status
      • Build number
      • Build date, and a link to that particular job execution.
      • Size of the build artifacts(the files created via the build)
    • you can see some nice trend graphs about the build history
    • on the left you can see:
      • Status: status of that particular build
        • who triggered it
        • from which SCM revision
        • Compiler warnings
          • The warnings plugin has a bunch of rulesets, which is used to extract the gcc compiler/linker warnings from the build output.
        • Configuration matrix
          • you can see the eligible matrix combinations and the status of each configuration job (blue: success, yellow: unstable, red: failure, blinking: in progress)
      • Changes: the changes SCM changes since the previous build
      • Console output: the output of the build process
      • Previous build: guess what
    • This is the actual build page, as the matrix job only triggers the configuration jobs on the slaves
    • On the left you can see basically the same links as for the matrix job, except that the Consol output now show a whole bunch of info: the output of our actual build execution.
  • http://ci.qa.php.net/job/php-src-5.3-matrix-tests/25/testReport/? aggregated test results for a specific build number
    • you can see the failed tests grouped by configuration and a summary of the executed tests.
    • you can see all tests, or all tests for a specific configuration, or all tests.
    • you can see the history for each invidual tests.
    • you can see the diff for the failed tests.

Current problems

  • JUnit doesn't provide anything similar in concept to XFAIL(http://zoomsplatter.blogspot.com/2008/06/why-xfail.html), so for now failing XFAIL is a passing test, passing XFAIL is a test failure, but we can swap that if needed, or handle both case as test failure.
  • It is a problem that we have failing tests, it would be much harder (albeit possible) to set up notification which would allow us to have failing tests but still be able to send out notification on new test failures but not on the known test failures (of course we could mark all of the known failures as xfail, which would make them to pass), so it would be cool if we could make all tests passing.
  • The FreeBSD VMs have a bad IO performance (the hoster is looking into this, but it can be that KVM + FreeBSD guest doesn't mix well), so the builds on those nodes are running with SKIP_SLOW_TESTS=1, and they are still 4-5 times slower than the same build on linux.
  • branches/PHP_5_3/ext/spl/tests/bug60082.phpt made the whole build hang on FreeBSD, I created a bugreport for it(https://bugs.php.net/bug.php?id=60186), but for now, we just skip that test on FreeBSD.
  • The Symfony2 job now runs inefficiently, as every branch will be built on every change: so if you have a commit which modifies each branch, it will trigger a php-src build for each project(3 matrix build) which in turn will trigger 3 builds of the php-symfony2 build, which means that it will run the testsuite three times against each binary. It would be easy to create 3 separate builds, and only trigger for the matching branch, but I think that it is nice that we can see the testresults for each version on one page, it is easier to spot if the test results are diverging between the php versions.

Other alternatives

  • rmtools: Pierre and Dan is working on a distributed build environment.
  • buildbot was planned to be set up, but it went MIA, and the current Jenkins setup uses the VMs mentioned there.
  • the PEAR group was using PHPUnderControl (before migrating to Jenkins) which is a patchset on top of CruiseControl(another java based CI tool). CruiseControl could also be used for building php-src, but it doesn't really have anything over Jenkins and the development seems halted: the last version is more than a year old.
  • other CI tools (there is a whole bunch)

Future plans

  • Enable every extension and feature for the builds(–enable-* and –with-* for configure).
  • Adding more nodes (Windows, other linux distros, Mac OS X, other BSD variants, etc. ).
  • Adding other machines would be necessary to add more nodes (we maxed out our capacity on the server with this 4 VMs).
  • We could consider using the test machines for handing out shell accounts for developers/testers if they don't have an environment to debug/reproduce a bug/test failure.
  • Integrate testsuites of other php projects similar to the Symfony2 demo.
  • Implement custom authentication through master.php.net. (implemented after the initial announcement)
  • The phpdoc building could also be added to jenkins.
  • The pecl extensions could be also built in Jenkins regularly.
  • Jenkins could be also used for our php based projects (web/* for example).
  • It is also possible to replace the current functionality of gcov.php.net with Jenkins if needed, there is also a plugin for Coverity integration.
  • It is also possible to implement some parts of the RELEASE_PROCESS through Jenkins.

Changelog

0.1 2011-10-20 Initial version 1.0 2011-10-28 Complete in content

rfc/jenkins.txt · Last modified: 2014/04/09 00:53 by levim