Using tox with the Jenkins Integration Server

Using Jenkins multi-configuration jobs

The Jenkins continuous integration server allows you to define “jobs” with “build steps” which can be test invocations. If you install tox on your default Python installation on each Jenkins agent, you can easily create a Jenkins multi-configuration job that will drive your tox runs from the CI-server side, using these steps:

  • install the Python plugin for Jenkins under “manage jenkins”

  • create a “multi-configuration” job, give it a name of your choice

  • configure your repository so that Jenkins can pull it

  • (optional) configure multiple nodes so that tox-runs are performed on multiple hosts

  • configure axes by using TOXENV as an axis name and as values provide space-separated test environment names you want Jenkins/tox to execute.

  • add a Python-build step with this content (see also next example):

    import tox

os.chdir(os.getenv("WORKSPACE"))
tox.cmdline()  # environment is selected by ``TOXENV`` env variable

  • check Publish JUnit test result report and enter **/junit-*.xml as the pattern so that Jenkins collects test results in the JUnit XML format.

The last point requires that your test command creates JunitXML files, for example with pytest it is done like this:

[testenv]
commands = pytest --junitxml=junit-{envname}.xml

zero-installation for agents

Note

This feature is broken currently because “toxbootstrap.py” has been removed. Please file an issue if you’d like to see it back.

If you manage many Jenkins agents and want to use the latest officially released tox (or latest development version) and want to skip manually installing tox then substitute the above Python build step code with this:

import urllib, os

url = "https://bitbucket.org/hpk42/tox/raw/default/toxbootstrap.py"
# os.environ['USETOXDEV']="1"  # use tox dev version
d = dict(__file__="toxbootstrap.py")
exec(urllib.urlopen(url).read(), globals=d)
d["cmdline"](["--recreate"])

The downloaded toxbootstrap.py file downloads all necessary files to install tox in a virtual sub environment. Notes:

  • uncomment the line containing USETOXDEV to use the latest development-release version of tox instead of the latest released version.

  • adapt the options in the last line as needed (the example code will cause tox to reinstall all virtual environments all the time which is often what one wants in CI server contexts)

Integrating “sphinx” documentation checks in a Jenkins job

If you are using a multi-configuration Jenkins job which collects JUnit Test results you will run into problems using the previous method of running the sphinx-build command because it will not generate JUnit results. To accommodate this issue one solution is to have pytest wrap the sphinx-checks and create a JUnit result file which wraps the result of calling sphinx-build. Here is an example:

  1. create a docs environment in your tox.ini file like this:

[testenv:docs]
basepython = python
# change to ``doc`` dir if that is where your sphinx-docs live
changedir = doc
deps = sphinx
       pytest
commands = pytest --tb=line -v --junitxml=junit-{envname}.xml check_sphinx.py

  1. create a doc/check_sphinx.py file like this:

import subprocess


def test_linkcheck(tmpdir):
    doctrees = tmpdir.join("doctrees")
    htmldir = tmpdir.join("html")
    subprocess.check_call(
        ["sphinx-build", "-W", "-blinkcheck", "-d", str(doctrees), ".", str(htmldir)]
    )


def test_build_docs(tmpdir):
    doctrees = tmpdir.join("doctrees")
    htmldir = tmpdir.join("html")
    subprocess.check_call(
        ["sphinx-build", "-W", "-bhtml", "-d", str(doctrees), ".", str(htmldir)]
    )

  1. run tox -e docs and then you may integrate this environment along with your other environments into Jenkins.

Note that pytest is only installed into the docs environment and does not need to be in use or installed with any other environment.

Access package artifacts between Jenkins jobs

In an extension to Access package artifacts between multiple tox-runs you can also configure Jenkins jobs to access each others artifacts. tox uses the distshare directory to access artifacts and in a Jenkins context (detected via existence of the environment variable HUDSON_URL); it defaults to to {toxworkdir}/distshare.

This means that each workspace will have its own distshare directory and we need to configure Jenkins to perform artifact copying. The recommend way to do this is to install the Jenkins Copy Artifact plugin and for each job which “receives” artifacts you add a Copy artifacts from another project build step using roughly this configuration:

Project-name: name of the other (tox-managed) job you want the artifact from
Artifacts to copy: .tox/dist/*.zip   # where tox jobs create artifacts
Target directory: .tox/distshare     # where we want it to appear for us
Flatten Directories: CHECK           # create no subdir-structure

You also need to configure the “other” job to archive artifacts; This is done by checking Archive the artifacts and entering:

Files to archive: .tox/dist/*.zip

So our “other” job will create an sdist-package artifact and the “copy-artifacts” plugin will copy it to our distshare area. Now everything proceeds as Access package artifacts between multiple tox-runs shows it.

So if you are using defaults you can re-use and debug exactly the same tox.ini file and make use of automatic sharing of your artifacts between runs or Jenkins jobs.

Avoiding the “path too long” error with long shebang lines

When using tox on a Jenkins instance, there may be a scenario where tox can not invoke pip because the shebang (Unix) line is too long. Some systems only support a limited amount of characters for an interpreter directive (e.x. Linux as a limit of 128). There are two methods to workaround this issue:

  1. Invoke tox with the --workdir option which tells tox to use a specific directory for its virtual environments. Using a unique and short path can prevent this issue.

  2. Use the environment variable TOX_LIMITED_SHEBANG to deal with environments with interpreter directive limitations (consult Handle interpreter directives with long lengths for more information).

Running tox environments in parallel

Jenkins has parallel stages allowing you to run commands in parallel, however tox package building it is not parallel safe. Use the --parallel--safe-build flag to enable parallel safe builds (this will generate unique folder names for distdir, distshare and log. Here’s a generic stage definition demonstrating how to use this inside Jenkins:

stage('run tox envs') {
  steps {
    script {
      def envs = sh(returnStdout: true, script: "tox -l").trim().split('\n')
      def cmds = envs.collectEntries({ tox_env ->
        [tox_env, {
          sh "tox --parallel--safe-build -vve $tox_env"
        }]
      })
      parallel(cmds)
    }
  }
}