experiment with less resource wasting

[maelle]

Fix #135

@krlmlr I have been thinking about wasting resources cf https://www.ryanfiller.com/blog/why-my-blog-stopped-using-deploy-previews

With this workflow, to get a preview one adds the "needs-preview" label. I'd like to merge this to then try again as currently I think the PR workflow from master applies? I see the label workflow works but I am not sure it posts the URL as commit status.

[maelle]

Ah I think it now really works (the regex in the pkgdown workflow was catching this branch 😅 )

[maelle]

@krlmlr I'm hoping it'd also work for forks.

[krlmlr]

Can we deploy automatically, but only if the documentation changes?

We're still running a huge build matrix...

[maelle]

Can we deploy automatically, but only if the documentation changes?

Do you mean pre-pkgdown building or do you mean post-pkgdown building? It's unclear to me where we'd store information on what the last deploy website and source were. 🤔

With this change we'd manually decide whether to label the PR as needs-preview so I assume less often than at each commit.

[krlmlr]

We'd assume that gh-pages contains the last deployed website, and deploy to Netlify only if the current state has changes? Of course this requires stable pkgdown builds, which isn't always given.

Let's put this on the backburner for now.