Poetry Cloud Native Buildpack

The Paketo Buildpack for Poetry is a Cloud Native Buildpack that installs Poetry into a layer and places it on the PATH.

The buildpack is published for consumption at paketobuildpacks/poetry.

Detection

• Detects when pyproject.toml exists.
• Provides poetry.
• Always requires cpython and pip.
• Optionally requires poetry when BP_POETRY_VERSION is set.

Build

• Contributes the poetry binary to a layer
• Prepends the poetry layer to the PYTHONPATH environment variable
• Adds the newly installed poetry location to the PATH environment variable

Configuration

Environment Variable	Description
$BP_POETRY_VERSION	Configure the version of Poetry to install. Buildpack releases (and the Poetry versions for each release) can be found here.

Integration

The Poetry CNB provides Poetry as a dependency. Downstream buildpacks can require the Poetry dependency by generating a Build Plan TOML file that looks like the following:

[[requires]]

  # The name of the Poetry dependency is "poetry". This value is considered
  # part of the public API for the buildpack and will not change without a plan
  # for deprecation.
  name = "poetry"

  # The Poetry buildpack supports some non-required metadata options.
  [requires.metadata]

    # Optional.
    # When not specified, the buildpack will select the latest supported version from buildpack.toml
    # This buildpack only supports exact version numbers.
    version = "21.0.1"

    # Set to true to ensure that `poetry` is avilable on both `$PATH` and `$PYTHONPATH` for subsequent buildpacks.
    build = true

    # Set to true to ensure that `poetry` is avilable on both `$PATH` and `$PYTHONPATH` for the launch container.
    launch = true

Usage

To package this buildpack for consumption:

$ ./scripts/package.sh --version x.x.x

This will create a buildpackage.cnb file under the build directory which you can use to build your app as follows:

pack build <app-name> \
  --path <path-to-app> \
  --buildpack build/buildpackage.cnb \
  --buildpack <other-buildpacks..>

To run the unit and integration tests for this buildpack:

$ ./scripts/unit.sh && ./scripts/integration.sh

Known issues and limitations

• This buildpack does not work in an offline/air-gapped environment; it requires internet access to install poetry. The impact of this limitation is mitigated by the fact that poetry itself does not support vendoring of dependencies, and so cannot function in an offline/air-gapped environment.