Notify on Pull Requests when documentation is rendered in CI

[phlax]

description

when you make changes to documentation its rendered by CircleCI.

I think it would be useful for reviewers and contributors if the repo bot posted a message containing a link to the rendered docs.

I can imagine this working in one of 2 ways

posting the first time a change is noticed (and rendered)

im guessing the condition for this would be similar to the trigger used to notify api-shepherds etc when api changes happen - except for that it should wait until the docs have been rendered

posting every time docs changes happen (and are rendered)

i think this would be a bit more complex and would involve comparing commits in the PR or perhaps cached artefacts

in some ways this would be more useful - because you would have the most up-to-date link - but in other ways it would be a bit more of a thread-hog

refs

• docs: Update build instructions for docs #13268 (comment)
• https://384272-65214191-gh.circle-artifacts.com/0/generated/docs/index.html
• https://app.circleci.com/pipelines/github/envoyproxy/envoy/34403/workflows/33eaf7f9-214f-4991-aeff-620047b76ea0/jobs/384272

[phlax]

cc @itayd

[phlax]

if we were to go with the first option, i think it would also want to watch for changes in protocols etc - anything that would cause docs to change

[mattklein123]

Agreed this would be neat.

[phlax]

thinking more about implementation, i think it would be a pita if it emitted every time eg api/docs changed, if you were working on api and not interested in seeing the docs being rebuilt particularly

i reckon it should do the following:

• on a new PR, if it changes docs/api (or perhaps first time it touches those dirs in any PR) it emits
• add a /docs command to print the last build of the docs