# Using tox with the Jenkins Integration Server

## Using Jenkins multi-configuration jobs

The Jenkins continuous integration server allows 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() in 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
>            py
>     commands = pytest --tb=line -v --junitxml=junit-{envname}.xml check_sphinx.py

2. create a `doc/check_sphinx.py` file like this:

>     import py
>     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)]
>         )

3. 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)
        }
      }
    }