# How to Contribute

Everyone is welcome to contribute to PyTango project. If you don’t feel comfortable with writing core PyTango we are looking for contributors to documentation or/and tests.

## Workflow

A normal Git workflow is used. You can find how to automate your git branching workflow example. Good practices:

- There is no special policy regarding commit messages. They should be short (50 chars or less) and contain summary of all changes,

- A CONTRIBUTING file is required,

- Pull requests should be ALWAYS made to develop branch, not to a master branch.

## reStructuredText and Sphinx

Documentation is written in reStructuredText and built with Sphinx - it’s easy to contribute. It also uses autodoc importing docstrings from tango package. Theme is not important, a theme prepared for Tango Community can be also used.

To test the docs locally requires Python >= 3.5:

  - `$ python -m pip install sphinx sphinx_rtd_theme`

  - `$ python setup.py build_doc`

To test the docs locally in a Sphinx Docker container:

  - `(host) $ cd /path/to/pytango`

  - `(host) $ docker run --rm -ti -v $PWD:/docs sphinxdoc/sphinx bash`

  - `(container) $ python -m pip install six numpy sphinx_rtd_theme`

  - `(container) $ python -m sphinx doc build/sphinx`

After building, open the `build/doc/index.html` page in your browser.

## Source code standard

All code should be PEP8 compatible. We have set up checking code quality with Codacy which uses PyLint under the hood. You can see how well your code is rated on your PR’s page.

Note

The accepted policy is that your code cannot introduce more issues than it solves!

You can also use other tools for checking PEP8 compliance for your personal use. One good example of such a tool is Flake8 which combines PEP8 and PyFlakes. There are plugins for various IDEs so that you can use your favourite tool easily.

## Using Docker for development

Docker containers are useful for developing, testing and debugging PyTango. See the folder `.devcontainer` in the root of the source repo. It includes instructions for building the Docker images and using them for development.

For direct usage, rather than PyTango developement, a Docker image with PyTango already installed is available: https://hub.docker.com/r/tangocs/tango-pytango.

## Releasing a new version

From time to time a new version should be released. Anyone who wishes to see some features of the development branch released is free to make a new release. The basic steps required are as follows:

Pick a version number

  - Semantic version numbering is used: <major>.<minor>.<patch>

  - The major and minor version fields (9.3) track the TANGO C++ core version.

  - Small changes are done as patch releases. For these the version number should correspond the current development number since each release process finishes with a version bump.

  - Patch release example:

      - `9.3.3.devN` or `9.3.3aN` or `9.3.3bN` (current development branch)

      - changes to `9.3.3` (the actual release)

      - changes to `9.3.4.dev0` (bump the patch version at the end of the release process)

Create an issue in Github

  - This is to inform the community that a release is planned.

  - Use a checklist similar to the one below:

    Task list:
    - [ ] Read steps in the how-to-contribute docs for making a release
    - [ ] Pull request to update changelog and bump version
    - [ ] Merge PR (this is the last PR for the release)
    - [ ] Merge develop into stable
    - [ ] Make sure Travis and Appveyor are OK on stable branch
    - [ ] Make sure the documentation is updated for stable (readthedocs)
    - [ ] Create an annotated tag from stable branch
    - [ ] Make sure the documentation is updated for release (readthedocs)
    - [ ] Upload the new version to PyPI
    - [ ] Bump the version with “-dev” in the develop branch
    - [ ] Create and fill in the release description on GitHub
    - [ ] Build conda packages
    - [ ] Advertise the release on the mailing list
    - [ ] Close this issue

  - A check list in this form on github can be ticked off as the work progresses.

Make a branch from `develop` to prepare the release

  - Example branch name: `prepare-v9.3.3`.

  - Edit the changelog (in `docs/revision.rst`). Include all pull requests since the version was bumped after the previous release.

  - Bump the versions (`tango/release.py` and `appveyor.yml`). E.g. `version_info = (9, 3, 3)`, and `version: 9.3.3.{build}`

  - Create a pull request to get these changes reviewed before proceeding.

Merge `stable` into `develop`

  - Wait until the preparation branch pull request has been merged.

  - Merge `stable` into the latest `develop`. It is recommended to do a fast-forward merge in order to avoid a confusing merge commit. This can be done by simply pushing `develop` to `stable` using this command:

    > `$ git push origin develop:stable`

    This way the release tag corresponds to the actual release commit both on the `stable` and `develop` branches.

  - In general, the `stable` branch should point to the latest release.

Make sure Travis and AppVeyor are OK on `stable` branch

  - On Travis, all tests, on all versions of Python must be passing. If not, bad luck - you’ll have to fix it first, and go back a few steps…

  - On AppVeyor, all builds, on all versions of Python must be passing. If not, bad luck - you’ll have to fix it first, and go back a few steps…

Make sure the documentation is updated

  - Log in to https://readthedocs.org.

  - Get account permissions for https://readthedocs.org/projects/pytango from another contributor, if necessary.

  - Readthedocs should automatically build the docs for each:

      - push to develop (latest docs)

      - push to stable (stable docs)

      - new tags (e.g v9.3.3)

  - But, the webhooks are somehow broken, so it probably won’t work automatically!

      - Trigger the builds manually here: https://readthedocs.org/projects/pytango/builds/

      - Set the new version to “active” here: https://readthedocs.org/dashboard/pytango/versions/

Create an annotated tag for the release

  - Note: Github’s release page makes lightweight tags which we don’t want

  - Create tag:

      - `$ git checkout stable`

      - `$ git pull`

      - `$ git tag -a -m "tag v9.3.3" v9.3.3`

      - `$ git push -v origin refs/tags/v9.3.3`

Upload the new version to PyPI

  - Log in to https://pypi.org.

  - Get account permissions for PyTango from another contributor, if necessary.

  - If necessary, pip install twine: https://pypi.org/project/twine/)

  - Build release from the tagged commit:

      - `$ git clean -xfd # Warning - remove all non-versioned files and directories`

      - `$ git fetch`

      - `$ git checkout v9.3.3`

      - `$ python setup.py sdist`

  - Optional: Upload to https://test.pypi.org, and make sure all is well:

      - `$ twine upload -r testpypi dist/pytango-9.3.3.tar.gz`

  - Optional: Test installation (in a virtualenv):

      - `$ pip install -i https://test.pypi.org/simple/ pytango`

  - Upload the source tarball to the real PyPI:

      - `$ twine upload dist/pytango-9.3.3.tar.gz`

  - Run build for the tag on AppVeyor, download artifacts, and upload wheels:

      - `$ twine upload dist/pytango-9.3.3-cp27-cp27m-win32.whl`

      - `$ twine upload dist/pytango-9.3.3-cp27-cp27m-win_amd64.whl`

      - `$ twine upload dist/pytango-9.3.3-cp36-cp36m-win32.whl`

      - `$ twine upload dist/pytango-9.3.3-cp36-cp36m-win_amd64.whl`

      - `$ twine upload dist/pytango-9.3.3-cp37-cp37m-win32.whl`

      - `$ twine upload dist/pytango-9.3.3-cp37-cp37m-win_amd64.whl`

Bump the version with “-dev” in the develop branch

  - Make branch like `bump-dev-version` from head of `develop`.

  - Change all references to next version and next + 1. E.g. if releasing v9.3.3, then update v9.3.4 to v9.3.5 and v9.3.3 to v9.3.4.

  - This includes files like `README.rst`, `doc/howto.rst`, `doc/start.rst`, `doc/how-to-contribute.rst`.

  - In `tango/release.py`, change `version_info`, e.g. from `(9, 3, 3)` to `(9, 3, 4, 'dev', 0)`.

  - In `appveyor.yml`, change `version`, e.g. from `9.3.3.{build}` to `9.3.4.dev0.{build}`.

  - Create PR, merge to `develop`.

Create and fill in the release description on GitHub

  - Go to the Tags page: https://github.com/tango-controls/pytango/tags

  - Find the tag created above and click “Create release”.

  - Content must be the same as the details in the changelog. List all the pull requests since the previous version.

Build conda packages

  - This is tricky, so ask a contributor from the ESRF to do it.

Advertise the release on the mailing list

  - Post on the Python development list.

  - Example of a previous post: http://www.tango-controls.org/community/forum/c/development/python/pytango-921-release/

Close off release issue

  - All the items on the check list should be ticked off by now.

  - Close the issue.