Investigate changing docs preview workflow

[jsjoeio]

We recently added a docs preview to code-server (thank you @BrunoQuaresma ) but now have an issue. If someone forks code-server, submits a PR, the docs preview fails. My hunch says we can't fix this since m is private and there are some tokens/secrets we rely on.

https://github.com/cdr/code-server/blob/main/.github/workflows/docs-preview.yaml
https://github.com/cdr/code-server/pull/4020/checks?check_run_id=3413784650

We should investigate fixing this.

[jsjoeio]

@mterhar made a good suggestion

We could have it check if it's a fork and if so, deploy to github pages for that repo
if: github.repository == 'cdr/code-server' then run our preview app.
if: github.repository != 'cdr/code-server' then run a github pages deploy

[jsjoeio]

@jawnsy said to look here: https://docs.github.com/en/actions/reference/environments

#4020 (comment)

[jsjoeio]

Another option would be to skip this workflow if it's from a fork, but then we might not catch bugs 🤔

[jsjoeio]

@bpmct found a good solution to this:

However, it looks like we can allow forks to use the secrets from the upstream repo and even add approvals. https://dev.to/petrsvihlik/using-environment-protection-rules-to-secure-secrets-when-building-external-forks-with-pullrequesttarget-hci