Developer Guidelines

Some rules and advices for developers who want to contribute to these or their projects and keep them human friendly.

Git

Git is used as the version control system. Each developer must be familiar with the basic functionality of git before contributing to the project. If necessary, look at this guide.

Commit messages

Conventional Commits specification shall be used for commit messages. Read the specification carefully and use this compact list of conventional commit types to help you. You'll quickly get used to it!

Common types of commit messages:

Type	Meaning
docs:	Documentation only changes.
feat:	A new feature.
fix:	A bug fix.
refactor:	A code change that neither fixes a bug nor adds a feature.
perf:	A code change that improves performance.
style:	Changes that do not affect the meaning of the code.

Basic rules:

• Try to keep the first line under 72 characters.
• A blank line must separate the subject from the description.
• Use the imperative voice.

Branching rules

In the project, the following branch types are recommended:

Type	Branch	Meaning
Stable	stable	Accepts merges from Working and Hotfixes
Working	master	Accepts merges from Features/Issues and Hotfixes
Features/Issues	topic/*	Always branch off HEAD of Working
Hotfix	hotfix/*	Always branch of Stable

topic can be defined (but not limited to) as feat, fix and docs. Each commit to the stable branch must contain a tag with the following format: <version>-stable. See the article for detailed information.

Warning: branch naming rules from the article are NOT used in this project – only branching rules.

Updating the Stable branch

Sometimes it might be a little tricky to update the Stable branch.
It should be updated with the latest stable features.

1. Create a new branch from the Master (or from the latest stable commit on it, if there are already new features in development inside the master branch). Let's call it "chore/update-stable-branch".
2. Run git merge -s ours origin/stable.
3. Push the new branch to the cloud with git push.
4. Create a PR from chore/update-stable-branch to stable.
5. Check for any conflicts.
6. Complete the PR.
7. Done! :)

Hints

• Do not forget to remove the branch after a successful Pull Request to the main branch to prevent contamination of the repository.
• Do not make additional changes in a branch that is already merged with the main one.
• If the changes are small and there is no danger of conflicts, consider making a squash merge to keep the git history more compact and readable.
• To enrich your changes, include at least one colleague as a reviewer for your PR. On the other hand, if you're a reviewer, make comments and give tips on how to improve it.

Pre-commit, using black and flake8 linting when pushing new changes

It is recommended to have pre-commit installed and configured in order to keep the repository and its code organized.

pre-commit is a tool that runs some hooks (wait for it) before the commit, such as black, flake8 or any other hook you wish.

Usually it should be already inside the requirements-dev.txt file and therefore you could just run pip install -U -r requirements-dev.txt. However, if you want to manually install it, run pip install pre-commit.

After running either of the commands above, run pre-commit install, with or without --allow-missing-config. Terminal should return pre-commit installed at .git/hooks/pre-commit.

Optionally, you can run against all files by using pre-commit run --all-files. You will get a 'Failed' or 'Passed' status.
Black can be run manually by using python -m black ./
If there are weird errors appearing, you can try to pre-commit autoupdate

Note: You need to configure a .pre-commit-config.yaml before you can use pre-commit. Here you can define all tests and linters you would like to use.
Here's an example:

repos:
-   repo: https://github.com/psf/black
    rev: 21.9b0
    hooks:
    -   id: black
-   repo: https://gitlab.com/pycqa/flake8
    rev: 3.9.2
    hooks:
    - id: flake8
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.0.1
    hooks:
    -   id: check-added-large-files
    -   id: end-of-file-fixer
    -   id: trailing-whitespace

VERSIONING

For versioning of the packages Semantic Versioning (SemVer) is used. Read the specification carefully and take a look at the how-to guide to SemVer.

CODE

Imports

Try to follow the PEP8. In summary:

• Import order: Built-ins, Third-parties, Locals. First the import ... then the from ... import ...

• Prioritize Absolute Imports over Relative Imports (e.g., import pkg_a.utils)

• Use as to reduce the verbosity (e.g., import pkg_a.pkg_b.pkg_c.utils as pkg_utils)

• Prioritize import ... as ... for modules and packages

• Avoid from ... import .... But if needed, use it for importing specific functions/classes from a module/package

• Leave __init__.py empty unless needed (e.g., making a function from a module accessible from the package. Even on these cases, prioritize absolute imports)

Style

flake8 is used for style guide checking. Usually, CI build of the projects runs linting with flake8 and the build will not be succeeded without corresponding styling. Before committing the code, don't forget to check styling locally. Various python IDEs also support the integration of flake8. Standard flake8 configuration for this project is as follows:

[flake8]
# Matching the black line length (default 88)
max-line-length = 88
max-complexity = 10
extend-ignore =
    # See https://github.com/PyCQA/pycodestyle/issues/373
    E203,
    F811,
exclude =
    .flake8,
    .git,
    .venv*,
    .env*,
    .bkp*,
    __pycache__,
    # Add your folders to ignore here
    build/,
    output/,
    bin/,
    dist/,

Docstrings

In this project reStructuredText (reST) Docstring Format is used, according to proposal in PEP 287. See the example of such formatting here. A docstring for each function and class are recommended.

Readme

Each repository must have a README with at least:

• Short blurb about the service and what it does
• Describe how to install all development dependencies
• Instructions about how to run the service as well as the tests

Take a look at the READMEs of other repos if you need some inspiration! :D

Contributing

Each repository can have a CONTRIBUTING with the necessary information for new developers to be able to contribute with the Project.