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Packaging and Testing with Crossbow
===================================

The content of ``arrow/dev/tasks`` directory aims for automating the process of
Arrow packaging and integration testing.

Packages:
  - C++ and Python `conda-forge packages`_ for Linux, Mac and Windows
  - Python `Wheels`_ for Linux, Mac and Windows
  - C++ and GLib `Linux packages`_ for multiple distributions
  - Java for Gandiva

Integration tests:
  - Various docker tests
  - Pandas
  - Dask
  - Turbodbc
  - HDFS
  - Spark

Architecture
------------

Executors
~~~~~~~~~

Individual jobs are executed on public CI services, currently:

- Linux: TravisCI, CircleCI, Azure Pipelines
- Mac: TravisCI, Azure Pipelines
- Windows: AppVeyor, Azure Pipelines

Queue
~~~~~

Because of the nature of how the CI services work, the scheduling of
jobs happens through an additional git repository, which acts like a job
queue for the tasks. Anyone can host a ``queue`` repository which is usually
called as ``crossbow``.

A job is a git commit on a particular git branch, containing only the required
configuration file to run the requested build (like ``.travis.yml``,
``appveyor.yml`` or ``azure-pipelines.yml``).

Scheduler
~~~~~~~~~

`Crossbow.py`_ handles version generation, task rendering and
submission. The tasks are defined in ``tasks.yml``.

Install
-------

   The following guide depends on GitHub, but theoretically any git
   server can be used.

1. `Create the queue repository`_

2. Enable `TravisCI`_, `Appveyor`_, `Azure Pipelines_` and `CircleCI`_
   integrations on for the newly created queue repository.

   -  turn off Travis’ `auto cancellation`_ feature on branches

3. Clone the newly created repository next to the arrow repository:

   By default the scripts looks for ``crossbow`` next to arrow repository, but
   this can configured through command line arguments.

   .. code:: bash

      git clone https://github.com/<user>/crossbow crossbow

   **Important note:** Crossbow only supports GitHub token based
   authentication. Although it overwrites the repository urls provided with ssh
   protocol, it's advisable to use the HTTPS repository URLs.

4. `Create a Personal Access Token`_

5. Locally export the token as an environment variable:

   .. code:: bash

      export CROSSBOW_GITHUB_TOKEN=<token>

   ..

      or pass as an argument to the CLI script ``--github-token``

6. Export the previously created GitHub token on both CI services:

   Use ``CROSSBOW_GITHUB_TOKEN`` encrypted environment variable. You can
   set them at the following URLs, where ``ghuser`` is the GitHub
   username and ``ghrepo`` is the GitHub repository name (typically
   ``crossbow``):

   -  TravisCI: ``https://travis-ci.org/<ghuser>/<ghrepo>/settings``
   -  Appveyor:
      ``https://ci.appveyor.com/project/<ghuser>/<ghrepo>/settings/environment``
   -  CircleCI:
      ``https://circleci.com/gh/<ghuser>/<ghrepo>/edit#env-vars``

   On Appveyor check the ``skip branches without appveyor.yml`` checkbox
   on the web UI under crossbow repository’s settings.

7. Install Python (minimum supported version is 3.6):

   Miniconda is preferred, see installation instructions:
   https://conda.io/docs/user-guide/install/index.html

8. Install the python dependencies for the script:

   .. code:: bash

      conda install -c conda-forge -y --file arrow/ci/conda_env_crossbow.txt

   .. code:: bash

      # pygit2 requires libgit2: http://www.pygit2.org/install.html
      pip install \
          jinja2 \
          pygit2 \
          click \
          ruamel.yaml \
          setuptools_scm \
          github3.py \
          toolz \
          jira

9. Try running it:

   .. code:: bash

      $ python crossbow.py --help

Usage
-----

The script does the following:

1. Detects the current repository, thus supports forks. The following
   snippet will build kszucs’s fork instead of the upstream apache/arrow
   repository.

   .. code:: bash

      $ git clone https://github.com/kszucs/arrow
      $ git clone https://github.com/kszucs/crossbow

      $ cd arrow/dev/tasks
      $ python crossbow.py submit --help  # show the available options
      $ python crossbow.py submit conda-win conda-linux conda-osx

2. Gets the HEAD commit of the currently checked out branch and
   generates the version number based on `setuptools_scm`_. So to build
   a particular branch check out before running the script:

   .. code:: bash

      git checkout ARROW-<ticket number>
      python dev/tasks/crossbow.py submit --dry-run conda-linux conda-osx

   ..

      Note that the arrow branch must be pushed beforehand, because the
      script will clone the selected branch.

3. Reads and renders the required build configurations with the
   parameters substituted.

4. Create a branch per task, prefixed with the job id. For example to
   build conda recipes on linux it will create a new branch:
   ``crossbow@build-<id>-conda-linux``.

5. Pushes the modified branches to GitHub which triggers the builds. For
   authentication it uses GitHub OAuth tokens described in the install
   section.

Query the build status
~~~~~~~~~~~~~~~~~~~~~~

Build id (which has a corresponding branch in the queue repository) is returned
by the ``submit`` command.

.. code:: bash

   python crossbow.py status <build id / branch name>

Download the build artifacts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code:: bash

   python crossbow.py artifacts <build id / branch name>

Examples
~~~~~~~~

Submit command accepts a list of task names and/or a list of task-group names
to select which tasks to build.

Run multiple builds:

.. code:: bash

   $ python crossbow.py submit debian-stretch conda-linux-gcc-py37
   Repository: https://github.com/kszucs/arrow@tasks
   Commit SHA: 810a718836bb3a8cefc053055600bdcc440e6702
   Version: 0.9.1.dev48+g810a7188.d20180414
   Pushed branches:
    - debian-stretch
    - conda-linux-gcc-py37

Just render without applying or committing the changes:

.. code:: bash

   $ python crossbow.py submit --dry-run task_name

Run only ``conda`` package builds and a Linux one:

.. code:: bash

   $ python crossbow.py submit --group conda centos-7

Run ``wheel`` builds:

.. code:: bash

   $ python crossbow.py submit --group wheel

There are multiple task groups in the ``tasks.yml`` like docker, integration
and cpp-python for running docker based tests.

``python crossbow.py submit`` supports multiple options and arguments, for more
see its help page:

.. code:: bash

  $ python crossbow.py submit --help


.. _conda-forge packages: conda-recipes
.. _Wheels: python-wheels
.. _Linux packages: linux-packages
.. _Crossbow.py: crossbow.py
.. _Create the queue repository: https://help.github.com/articles/creating-a-new-repository
.. _TravisCI: https://travis-ci.org/getting_started
.. _Appveyor: https://www.appveyor.com/docs/
.. _CircleCI: https://circleci.com/docs/2.0/getting-started/
.. _Azure Pipelines: https://docs.microsoft.com/en-us/azure/devops/pipelines/get-started/pipelines-sign-up
.. _auto cancellation: https://docs.travis-ci.com/user/customizing-the-build/#Building-only-the-latest-commit
.. _Create a Personal Access Token: https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line/
.. _setuptools_scm: https://pypi.python.org/pypi/setuptools_scm