function-template-python

A template for writing a composition function in Python.

To learn how to use this template:

• Learn about how composition functions work

If you just want to jump in and get started:

1. Replace function-template-python with your function's name in pyproject.toml and package/crossplane.yaml.
2. Add your logic to RunFunction in function/fn.py
3. Add tests for your logic in test/test_fn.py
4. Update this file, README.md, to be about your function!

This template uses Python, Docker, and the Crossplane CLI to build functions.

# Lint the code - see pyproject.toml
hatch run lint:check

# Run unit tests - see tests/test_fn.py
hatch run test:unit

# Build the function's runtime image - see Dockerfile
$ docker build . --tag=runtime

# Build a function package - see package/crossplane.yaml
$ crossplane xpkg build -f package --embed-runtime-image=runtime

Containerized Development

If you prefer to develop in a containerized environment, you can use the provided Dockerfile and docker-compose.yml files located in development to do so. You can either use devcontainers, docker or compose to develop in a containerized environment that reloads itself on changes.

VsCode: Devcontainers

• You can develop inside a devcontainer using the definition in .devcontainer.json.

Hot reload

• In the development folder you can find a docker-compose file that will mount the current folder into the container and reload the container on changes using its entrypoint.
• The entrypoint watches the function and test directories and the pyproject.toml file for changes and reloads the container on changes.
• By default it will run:
  • hatch run lint:check
  • hatch run test:unit
  • hatch run function --insecure --debug
• That enables you to quickly iterate on your function and test it locally using the crossplane cli.

Docker (Compose)

• In one terminal Build + run the dev container image:

  $ docker build -f development/Dockerfile -t crossplane-function-python-dev .
  $ docker run -p 9443:9443 -v .:/build --rm -it crossplane-function-python-dev
  

  or

  $ docker run -p 9443:9443 -v .:/build --rm -it $(docker build -f development/Dockerfile -q .)
  

  or

  $ cd development
  $ docker compose up --build
  

• In another terminal run the render command:

$ crossplane beta render xr.yaml composition.yaml functions.yaml