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Python development setup#

  • Fork and clone the repository

  • Create a new Python environment with your favourite environment manager, e.g. virtualenv or conda

  • Install repository in editable mode with development dependencies:

    cd python
    pip install -e ".[dev]"
  • Install pre-commit and then activate its hooks. pre-commit is a framework for managing and maintaining multi-language pre-commit hooks. The Feature Store uses pre-commit to ensure code-style and code formatting through black and flake8:

    cd python
    pip install --user pre-commit
    pre-commit install

Afterwards, pre-commit will run whenever you commit.

  • To run formatting and code-style separately, you can configure your IDE, such as VSCode, to use black and flake8, or run them via the command line:

    cd python
    flake8 hopsworks
    black hopsworks

Python documentation#

We follow a few best practices for writing the Python documentation:

  1. Use the google docstring style:

    """[One Line Summary]
    [Extended Summary]
    [!!! example
        import xyz
    # Arguments
        arg1: Type[, optional]. Description[, defaults to `default`]
        arg2: Type[, optional]. Description[, defaults to `default`]
    # Returns
        Type. Description.
    # Raises
        Exception. Description.

    If Python 3 type annotations are used, they are inserted automatically.

  2. Feature store entity engine methods (e.g. FeatureGroupEngine etc.) only require a single line docstring.

  3. REST Api implementations (e.g. FeatureGroupApi etc.) should be fully documented with docstrings without defaults.
  4. Public Api such as metadata objects should be fully documented with defaults.

Setup and Build Documentation#

We use mkdocs to build the documentation and a plugin called keras-autodoc to auto generate Python API documentation from docstrings.

  1. Currently we are using our own version of keras-autodoc

    pip install git+
  2. Install HSFS with docs extras:

    pip install -e .[dev,docs]
  3. To build the docs, first run the auto doc script:

    cd ..
  4. Either build the docs, or serve them dynamically:

    mkdocs build
    # or
    mkdocs serve

Adding new API documentation#

To add new documentation for APIs, you need to add information about the method/class to document to the script:

    "": [
    "": [

Now you can add a template markdown file to the docs/templates directory with the name you specified in the auto-doc script. The file should contain a tag to identify the place at which the API documentation should be inserted:

## The XYZ package


Some extra content here.

!!! example
    import xyz


Finally, run the script, as decribed above, to update the documentation.

For information about Markdown syntax and possible Admonitions/Highlighting etc. see the Material for Mkdocs themes reference documentation.