Release Process
===============

This document describes the process for creating new releases.

1. **Increment the Python version:** Create a PR that increments the Python
   package version. See `this example`_.

2. **Download the Travis-built wheels:** Once Travis has completed the tests,
   the wheels from this commit can be downloaded from S3 to do testing, etc.
   The URL is structured like this:
   ``https://s3-us-west-2.amazonaws.com/ray-wheels/<hash>/<wheel-name>``
   where ``<hash>`` is replaced by the ID of the commit and the ``<version>``
   is the incremented version from the previous step. The ``<wheel-name>`` can
   be determined by looking at the OS/Version matrix in the documentation_.

3. **Create a release branch:** This branch should also have the same commit ID as the
   previous two steps. In order to create the branch, locally checkout the commit ID
   i.e. ``git checkout <hash>``. Then checkout a new branch of the format
   ``releases/<release_number>``. The release number must match the increment in
   the first step. Then push that branch to the ray repo:
   ``git push upstream releases/<release_number>``.

4. **Testing:** Before a release is created, significant testing should be done.
   Run the scripts `ci/stress_tests/run_stress_tests.sh`_ and
   `ci/stress_tests/run_application_stress_tests.sh`_ and make sure they
   pass. You **MUST** modify the autoscaler config file and replace
   ``<<RAY_RELEASE_HASH>>`` and ``<<RAY_RELEASE_VERSION>>`` with the appropriate
   values to test the correct wheels. This will use the autoscaler to start a bunch of
   machines and run some tests. Any new stress tests should be added to this
   script so that they will be run automatically for future release testing.

5. **Resolve release-blockers:** Should any release blocking issues arise,
   there are two ways these issues are resolved: A PR to patch the issue or a
   revert commit that removes the breaking change from the release. In the case
   of a PR, that PR should be created against master. Once it is merged, the
   release master should ``git cherry-pick`` the commit to the release branch.
   If the decision is to revert a commit that caused the release blocker, the
   release master should ``git revert`` the commit to be reverted on the
   release branch. Push these changes directly to the release branch.

6. **Download all the wheels:** Now the release is ready to begin final
   testing. The wheels are automatically uploaded to S3, even on the release
   branch. To test, ``pip install`` from the following URLs:

   .. code-block:: bash

       export RAY_HASH=...  # e.g., 618147f57fb40368448da3b2fb4fd213828fa12b
       export RAY_VERSION=...  # e.g., 0.7.0
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp27-cp27mu-manylinux1_x86_64.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp35-cp35m-manylinux1_x86_64.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp36-cp36m-manylinux1_x86_64.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp37-cp37m-manylinux1_x86_64.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp27-cp27m-macosx_10_6_intel.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp35-cp35m-macosx_10_6_intel.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp36-cp36m-macosx_10_6_intel.whl
       pip install -U https://s3-us-west-2.amazonaws.com/ray-wheels/$RAY_HASH/ray-$RAY_VERSION-cp37-cp37m-macosx_10_6_intel.whl

7. **Final Testing:** Send a link to the wheels to the other contributors and
   core members of the Ray project. Make sure the wheels are tested on Ubuntu,
   Mac OSX 10.12, and Mac OSX 10.13+. This testing should verify that the
   wheels are correct and that all release blockers have been resolved. Should
   a new release blocker be found, repeat steps 5-7.

8. **Upload to PyPI Test:** Upload the wheels to the PyPI test site using
   ``twine`` (ask Robert to add you as a maintainer to the PyPI project). You'll
   need to run a command like

   .. code-block:: bash

     twine upload --repository-url https://test.pypi.org/legacy/ray/.whl/*

   assuming that you've downloaded the wheels from the ``ray-wheels`` S3 bucket
   and put them in ``ray/.whl``, that you've installed ``twine`` through
   ``pip``, and that you've made PyPI accounts.

   Test that you can install the wheels with pip from the PyPI test repository
   with

   .. code-block:: bash

     pip install --index-url https://test.pypi.org/simple/ ray

   Then start Python, make sure you can ``import ray`` and run some simple Ray
   scripts. Make sure that it is finding the version of Ray that you just
   installed by checking ``ray.__version__`` and ``ray.__file__``.

   Do this at least for MacOS and for Linux, as well as for Python 2 and Python
   3. Also do this for different versions of MacOS.

9. **Upload to PyPI:** Now that you've tested the wheels on the PyPI test
   repository, they can be uploaded to the main PyPI repository. Be careful,
   **it will not be possible to modify wheels once you upload them**, so any
   mistake will require a new release. You can upload the wheels with a command
   like

   .. code-block:: bash

     twine upload --repository-url https://upload.pypi.org/legacy/ ray/.whl/*

   Verify that

   .. code-block:: bash

     pip install -U ray

   finds the correct Ray version, and successfully runs some simple scripts on
   both MacOS and Linux as well as Python 2 and Python 3.

10. **Create a GitHub release:** Create a GitHub release through the `GitHub website`_.
    The release should be created at the commit from the previous
    step. This should include **release notes**. Copy the style and formatting
    used by previous releases. Create a draft of the release notes containing
    information about substantial changes/updates/bugfixes and their PR number.
    Once you have a draft, make sure you solicit feedback from other Ray
    developers before publishing. Use the following to get started:

    .. code-block:: bash

      git pull origin master --tags
      git log $(git describe --tags --abbrev=0)..HEAD --pretty=format:"%s" | sort

11. **Bump version on Ray master branch:** Create a pull request to increment the
    version of the master branch. The format of the new version is as follows:

    New minor release (e.g., 0.7.0): Increment the minor version and append ``.dev0`` to
    the version. For example, if the version of the new release is 0.7.0, the master
    branch needs to be updated to 0.8.0.dev0. `Example PR for minor release`

    New micro release (e.g., 0.7.1): Increment the ``dev`` number, such that the number
    after ``dev`` equals the micro version. For example, if the version of the new
    release is 0.7.1, the master branch needs to be updated to 0.8.0.dev1.

12. **Update version numbers throughout codebase:** Suppose we just released 0.7.1. The
    previous release version number (in this case 0.7.0) and the previous dev version number
    (in this case 0.8.0.dev0) appear in many places throughout the code base including
    the installation documentation, the example autoscaler config files, and the testing
    scripts. Search for all of the occurrences of these version numbers and update them to
    use the new release and dev version numbers.

.. _documentation: https://ray.readthedocs.io/en/latest/installation.html#trying-snapshots-from-master
.. _`documentation for building wheels`: https://github.com/ray-project/ray/blob/master/python/README-building-wheels.md
.. _`ci/stress_tests/run_stress_tests.sh`: https://github.com/ray-project/ray/blob/master/ci/stress_tests/run_stress_tests.sh
.. _`ci/stress_tests/run_application_stress_tests.sh`: https://github.com/ray-project/ray/blob/master/ci/stress_tests/run_application_stress_tests.sh
.. _`this example`: https://github.com/ray-project/ray/pull/4226
.. _`GitHub website`: https://github.com/ray-project/ray/releases
.. _`Example PR for minor release`: https://github.com/ray-project/ray/pull/4845