Add Site Health check for Full Page Cache usage

[manuelRod]

Summary

Fixes #220
Trac #54423

Relevant technical choices

As @westonruter proposed, I've adapted and migrated the full page caching Site Health test from AMP to the performance plugin.

Checklist

• PR has either [Focus] or Infrastructure label.
• PR has a [Type] label.
• PR has a milestone or the no milestone label.

[camaran]

please add
'x-aruba-cache' => $cache_hit_callback,
for new aruba hispeed cache service

[bethanylang]

@manuelRod Since I'm working on updating the language on the other Site Health reports, I took a look at the copy for this one as well and left some thoughts. Let me know if you have any questions!

[manuelRod]

Thanks for that @bethanylang, where I can find those thoughts?

[westonruter]

Overall looks good to me, but it looked good to me in the AMP plugin when I merged it, so I'm probably not the best to review for merging here.

[manuelRod]

please add 'x-aruba-cache' => $cache_hit_callback, for new aruba hispeed cache service

added

[felixarntz]

@manuelRod Overall the code here looks solid. I left a few minor things for some cleanup, particularly I'd suggest to remove two of the functions that are only used in one place and actually make the code more complex to follow rather than less because of splitting how the $result is generated.

[felixarntz]

@bethanylang Would be great to get your review here specifically on the copy in the Site Health check.

[felixarntz]

@manuelRod This looks solid and should be close to merge, I mostly have some nit-picks around documentation. Please make sure to update all version references for new code in this PR to n.e.x.t, per our guidelines.

Last but not least, based on #310, please refresh this PR against latest trunk and add the corresponding entries for this new module to the CODEOWNERS file, with at least yourself as the module owner.

[felixarntz]

@manuelRod @westonruter Given that this is an entirely new module and the 1.1.0 release is about to be finalized with the release coming next week, I think with the remaining iterations to make this won't give us enough time for testing prior to the release, so I think this would be better to include in the following 1.2.0 release. Let's make sure we finalize the PR soon so that it can be merged into trunk shortly after 1.1.0, to have time for testing and potential further iterations.

[akshitsethi]

I tested the module and so far it looks good to me. Multiple scenarios (looback request failed, without cache, with cache plugin) were tested and I've attached the screenshot for each below:

Loopback failure

Without cache

Cache enabled

I'll test some more scenarios and update it over here.

[felixarntz]

@manuelRod Looks good to me, great stuff!

I left a few minor points on documentation and indentation, please address these. None of these are too critical though, so I'm already going to mark this as approved from my end.

[felixarntz]

Great, thanks @manuelRod!

@bethanylang You previously requested changes regarding the copy. Can you please give this another pass and approve once it's good from your end?

[bethanylang]

Language LGTM!

[bethanylang]

@felixarntz @manuelRod Apologies if I was a blocker here; just approved on my side. Looks like this is good to go for 1.2.0! 🥳

[felixarntz]

Thanks @bethanylang!

[manuelRod]

awesome, thanks guys!