Running the Docs workflow via workflow_dispatch always fails

[AlexWaygood]

Our Docs workflow file allows people to manually trigger the workflow on arbitrary branches in their GitHub fork of CPython:

cpython/.github/workflows/doc.yml

Lines 1 to 4 in 6c4124d

	name: Docs
	on:
	workflow_dispatch:

This is a useful feature that I like to use in order to test possible changes prior to filing a PR. However, on latest main, while it is still possible to run the Docs workflow via the workflow_dispatch, it now always fails if you try to do so. Example failing run on my GitHub fork: https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105.

The error occurs in the "Get list of changed files" step here (added to the workflow in #102513):

cpython/.github/workflows/doc.yml

Lines 57 to 62 in 6c4124d

	# Add pull request annotations for Sphinx nitpicks (missing references)
	- name: 'Get list of changed files'
	id: changed_files
	uses: Ana06/get-changed-files@v2.2.0
	with:
	filter: "Doc/**"

The error message is:

Run Ana06/get-changed-files@v[2](https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105#step:8:2).2.0
  with:
    filter: Doc/**
    token: ***
    format: space-delimited
  env:
    pythonLocation: /opt/hostedtoolcache/Python/[3](https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105#step:8:3).11.3/x6[4](https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105#step:8:4)
    PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.11.3/x[6](https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105#step:8:6)4/lib/pkgconfig
    Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.[11](https://github.com/AlexWaygood/cpython/actions/runs/4803232831/jobs/8547528105#step:8:11).3/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.3/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.3/x64
    LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.11.3/x64/lib
Error: This action only supports pull requests and pushes, workflow_dispatch events are not supported. Please submit an issue on this action's GitHub repo if you believe this in correct.
Base commit: undefined
Head commit: undefined
Error: The base and head commits are missing from the payload for this workflow_dispatch event. Please submit an issue on this action's GitHub repo.
Error: Not Found

While this isn't a huge problem, it would be nice if we could continue to be able to run the Docs workflow via the workflow_dispatch trigger without it failing.

Cc. @hugovk, @ezio-melotti, @CAM-Gerlach

Linked PRs

• gh-103884: Docs CI: Only attempt nit-picky PR annotations for PRs #103889

[hugovk]

Yep, we can't get the list of files changed in a PR, when not running as a PR :)

Let's add some logic to skip this bit for non-PRs:

cpython/.github/workflows/doc.yml

Lines 57 to 70 in d45225b

	# Add pull request annotations for Sphinx nitpicks (missing references)
	- name: 'Get list of changed files'
	id: changed_files
	uses: Ana06/get-changed-files@v2.2.0
	with:
	filter: "Doc/**"
	- name: 'Build changed files in nit-picky mode'
	continue-on-error: true
	run: |
	# Mark files the pull request modified
	touch ${{ steps.changed_files.outputs.added_modified }}
	# Build docs with the '-n' (nit-picky) option; convert warnings to annotations
	make -C Doc/ PYTHON=../python SPHINXOPTS="-q -n --keep-going" html 2>&1 |
	python Doc/tools/warnings-to-gh-actions.py

[hugovk]

Fixed in #103889, thanks for the report!

[AlexWaygood]

Thanks for the lightning-quick fix!