WIP: Add a preview-build action for PRs

[mjahoda]

An attempt to add an automatically triggered action that provides a preview build for every new or re-opened pull request.

[rolfedh]

Hi Mirek,

I've reviewed the .github/workflows/preview-build.yml workflow, and it's looking great! It's well-structured and aligns perfectly with our goals for automating documentation previews. I have a few friendly suggestions that could further enhance its effectiveness:

• Comments for Clarity: Adding brief comments to complex steps or choices (like the Docker usage) could make the workflow more accessible to others, especially new contributors or those not familiar with specific tools.
• Error Handling: Consider incorporating steps for error handling, such as notifications for build failures. This could improve our response time for resolving any issues.
• Caching Dependencies: If the build process involves stable dependencies, implementing caching could significantly reduce build times and resource usage.
• Security Checks: Ensuring the Docker images and actions are from trusted and verified sources is crucial for maintaining the security of our workflow.
• Workflow Documentation: A short README explaining the purpose and workings of this workflow (and any others in .github/workflows) would be beneficial for maintainability and onboarding.

These are just enhancements to what is already a solid foundation. I'm looking forward to seeing this project evolve how it will improve our documentation process. Great work!

Best, Rolfe

[IanFrangs]

LGTM!

[mjahoda]

@rolfedh @IanFrangs @emmurphy1 Thank you for checking the PR, but it is far from to be finished. I tried to indicate this by WIP: in the title. Because it's based on the YAML file [1] we use for publishing our main deliverable, we can use Rolfe's suggestions also there.

I'm still struggling to realize what URL can I use for deploying preview builds. In the Github docs for deploying PR preview I've checked, I only found url: ${{ steps.deployment.outputs.page_url }} we already use for the latest published mod-docs guide.

After the upcoming RHEL Beta releases are out, I'll try to follow guidance on [2]. And probably on some copy of this repository first.

[1] https://github.com/redhat-documentation/modular-docs/blob/main/.github/workflows/deploy-site.yml

[2] https://medium.com/@vegaobed/how-to-enable-pull-request-previews-in-github-pages-dc3a94fa969b