Always run GitHub action jobs, even on documentation-only jobs

[vstinner]

BPO	40548
Nosy	@vstinner, @jstasiak, @miss-islington, @FFY00
PRs	bpo-40548: Always run GitHub action, even on doc PRs #19981 bpo-40548: skip build/tests on documentation changes #19983 bpo-40548: github actions: pass the changes check on no source changes #20097 [3.8] bpo-40548: GitHub Action workflow: skip jobs on doc only PRs #20100 [3.7] [3.8] bpo-40548: GitHub Action workflow: skip jobs on doc only PRs (GH-20100) #20101 bpo-40548: Github Actions: update actions/checkout to v2 #20164 [3.7] bpo-40548: Github Actions: update actions/checkout to v2 (GH-20164) #20178 [3.8] bpo-40548: Github Actions: update actions/checkout to v2 (GH-20164) #20179 bpo-40548: test for https://github.com/python/core-workflow/issues/368 #20740 bpo-40548: Fix "Check for source changes (pull_request)" GH Action job #21806 bpo-40548: [WIP] Documentation only PR #21812 [3.8] bpo-40548: Fix "Check for source changes (pull_request)" GH Action job (GH-21806) #21813 [3.9] bpo-40548: Fix "Check for source changes (pull_request)" GH Action job (GH-21806) #21814

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-05-18.14:18:46.803>
created_at = <Date 2020-05-07.17:39:37.087>
labels = ['build', '3.9']
title = 'Always run GitHub action jobs, even on documentation-only jobs'
updated_at = <Date 2020-08-10.17:09:45.684>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2020-08-10.17:09:45.684>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2020-05-18.14:18:46.803>
closer = 'vstinner'
components = ['Build']
creation = <Date 2020-05-07.17:39:37.087>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 40548
keywords = ['patch']
message_count = 17.0
messages = ['368357', '368359', '368361', '368366', '368372', '368384', '368870', '368915', '368922', '368924', '369210', '369225', '369226', '369230', '375129', '375131', '375132']
nosy_count = 4.0
nosy_names = ['vstinner', 'jstasiak', 'miss-islington', 'FFY00']
pr_nums = ['19981', '19983', '20097', '20100', '20101', '20164', '20178', '20179', '20740', '21806', '21812', '21813', '21814']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue40548'
versions = ['Python 3.9']

[vstinner]

bpo-39837 made Azure Pipelines CI non-mandatory. Travis CI was made mandatory to have at least one mandatory job: python/core-workflow#365

I would prefer to have at least one mandatory Windows CI running on Python pull requests. Before we had pre-commit checks, it was too common to break Windows. I would prefer to not regress on that aspect.

--

Currently, GitHub action jobs ignore "documentation-only" changes. Extract of .github/workflows/build.yml:

on:
push:
branches:
- master
- 3.8
- 3.7
paths-ignore:
- 'Doc/'
- 'Misc/'
- '**/.md'
- '**/.rst'

If a job is marked as mandatory but the GitHub action is skipped because of paths-ignore, the PR cannot be merged :-( It seems to be a known GitHub limitation which is not going to be fixed soon:
https://discuss.python.org/t/make-one-windows-ci-job-mandatory/4047/6

To workaround is to always run GitHub action jobs, even on documentation-only jobs.

I propose to always run GitHub actions and then make the Windows (64 bit) job mandatory.

--

Sadly, it will waste resources for documentation-only jobs. To avoid that, the Windows job can be modified later to be skipped if it detects that the PR is a documentation-only change.

Steve Dower wrote:
"That workaround looks roughly like what is in the Azure Pipelines files. Someone just needs the time to go and migrate it."
https://discuss.python.org/t/make-one-windows-ci-job-mandatory/4047/6

Note: the Travis CI job (.travis.yml) uses the following check:

  # Pull requests are slightly complicated because $TRAVIS_COMMIT_RANGE
  # may include more changes than desired if the history is convoluted.
  # Instead, explicitly fetch the base branch and compare against the
  # merge-base commit.
  git fetch -q origin +refs/heads/$TRAVIS_BRANCH
  changes=$(git diff --name-only HEAD $(git merge-base HEAD FETCH_HEAD))
  echo "Files changed:"
  echo "$changes"
  if ! echo "$changes" | grep -qvE '(\.rst$)|(^Doc)|(^Misc)'
  then
    echo "Only docs were updated, stopping build process."
    exit
  fi

--

More background on these CI issues:

• https://bugs.python.org/issue39837
• Make Travis CI (and Windows x64 ?) mandatory core-workflow#365
• https://discuss.python.org/t/make-one-windows-ci-job-mandatory/4047

[FFY00]

The workaround presented at https://github.community/t5/GitHub-Actions/Feature-request-conditional-required-checks/m-p/51344/highlight/true#M8157 seems pretty reasonable. And it seems like travis is alerady doing the same thing as it doesn't have native support to skip runs based on path changes.

I can open a PR if you want.

[vstinner]

The workaround presented at https://github.community/t5/GitHub-Actions/Feature-request-conditional-required-checks/m-p/51344/highlight/true#M8157 seems pretty reasonable. And it seems like travis is alerady doing the same thing as it doesn't have native support to skip runs based on path changes.

I suppose that Steve Dower mentioned the following part of .azure-pipelines/prebuild-checks.yml:
----------------

• script: |
  if ! git diff --name-only $(diffTarget) | grep -qvE '(\.rst$|^Doc|^Misc)'
  then
  echo "Only docs were updated: tests.run=false"
  echo "##vso[task.setvariable variable=run;isOutput=true]false"
  else
  echo "Code was updated: tests.run=true"
  echo "##vso[task.setvariable variable=run;isOutput=true]true"
  fi
  displayName: Detect source changes
  name: tests
  ----------------

I understood that he proposed to port it inside the Windows job of GitHub actions (.github/workflows/build.yml).

I propose the following plan:

• Always run GitHub Action jobs
• Make Windows 64-bit job mandatory
• And only then try to skip documentation-only changes

[FFY00]

• And only then try to skip documentation-only changes

Done :)

[vstinner]

New changeset 4e36376 by Victor Stinner in branch 'master':
bpo-40548: Always run GitHub action, even on doc PRs (GH-19981)
4e36376

[vstinner]

I propose the following plan:

• Always run GitHub Action jobs

Done.

• Make Windows 64-bit job mandatory

My request: python/core-workflow#368

[vstinner]

New changeset 75d7257 by Filipe Laíns in branch 'master':
bpo-40548: GitHub Action workflow: skip jobs on doc only PRs (GH-19983)
75d7257

[vstinner]

New changeset 6a78589 by Filipe Laíns in branch 'master':
bpo-40548: github actions: pass the changes check on no source changes (GH-20097)
6a78589

[vstinner]

New changeset 07bd5cf by Victor Stinner in branch '3.8':
[3.8] bpo-40548: GitHub Action workflow: skip jobs on doc only PRs (GH-20100)
07bd5cf

[miss-islington]

New changeset 6ad51a1 by Miss Islington (bot) in branch '3.7':
[3.8] bpo-40548: GitHub Action workflow: skip jobs on doc only PRs (GH-20100)
6ad51a1

[vstinner]

New changeset c444108 by Filipe Laíns in branch 'master':
bpo-40548: Github Actions: update actions/checkout to v2 (GH-20164)
c444108