Investigate: composite actions vs. re-usable workflows

[woutdenolf]

https://docs.github.com/en/actions/tutorials/create-actions/create-a-composite-action

We already have one

https://github.com/ewoks-kit/.github/blob/main/.github/actions/setup-python-package/action.yml

but maybe we can use it instead of the re-usable workflows?

[woutdenolf]

LLM:

Feature	Composite Action	Reusable Workflow
Level	Step	Job / Workflow
Can define jobs	❌	✅
Matrix support	❌	✅
Secrets handling	Limited	Full
Use case	Small reusable logic	Full CI/CD pipelines
Called via	uses: in steps	uses: in jobs

• If it fits inside a single job step → use a composite action
• If it involves multiple jobs or environments → use a reusable workflow

Keep as reusable workflow if it:

• Defines jobs (jobs:)
• Uses runs-on
• Has multiple jobs or dependencies
• Uses matrix builds
• Needs secrets or environments
• Represents a full pipeline step (CI, release, deploy)

👉 These cannot be composite actions by design

[loichuder]

Nice summary 👍