Add sampler profiling

[ivergara]

This PR leverages pyinstrument to provide sampling profiling to all endpoints exposed by quetz.

For this to happen, the enable_sampling configuration of the section profiling must be set to True and then addingprofiling=true (or any value that evaluates to True) as a query parameter. Once this is done, the response will not be the expected one, but an HTML view of the profiling done by pyinstrument.

[AndreasAlbertQC]

@ivergara could you add some documentation on the new config setting here?

[janjagusch]

Thanks for this PR!

Something about your changes seems to break CI (it was running successfully on the default branch this morning). Could you please take a look?

[ivergara]

@janjagusch @AndreasAlbertQC a few options

1. should I add the option to activate profiling in the dev configuration?
2. How do you recommend testing this? Or is enough manual QA since this is basically for dev purposes?

[janjagusch]

1. should I add the option to activate profiling in the dev configuration?

You mean in this file? I don't have a strong preference. What about adding the section but setting it to false?

2. How do you recommend testing this? Or is enough manual QA since this is basically for dev purposes?

I'm unsure how easily we could integrate this in the current testing suite. If it's too much work, then I suggest we leave it untested for now. Let's do a manual demonstration together, so I can see that it's working.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.84 ⚠️

Comparison is base (1f29a9c) 82.28% compared to head (025ccd7) 81.45%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #623      +/-   ##
==========================================
- Coverage   82.28%   81.45%   -0.84%     
==========================================
  Files          78       78              
  Lines        6124     6135      +11     
==========================================
- Hits         5039     4997      -42     
- Misses       1085     1138      +53     

Impacted Files	Coverage Δ
quetz/config.py	90.20% <ø> (ø)
quetz/main.py	86.46% <100.00%> (+0.20%)	⬆️
quetz/testing/fixtures.py	95.67% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[ivergara]

1. should I add the option to activate profiling in the dev configuration?

You mean in this file? I don't have a strong preference. What about adding the section but setting it to false?

Indeed that file. Sure, I can change it to false.

2. How do you recommend testing this? Or is enough manual QA since this is basically for dev purposes?

I'm unsure how easily we could integrate this in the current testing suite. If it's too much work, then I suggest we leave it untested for now. Let's do a manual demonstration together, so I can see that it's working.

That's why I suggested just going for manual QA only. I could see how to write a test that if profiling is enabled and the query parameter is given, the response is an HTML page instead of a JSON answer (probably via the content-type of the response). But this sounds like a very weak test.

[AndreasAlbertQC]

But this sounds like a very weak test.

True, but still better than no test, though. At least it will break if something in the setup changes (e.g. some unexpected breaking change in pyinstrument).

[janjagusch]

But this sounds like a very weak test.

True, but still better than no test, though. At least it will break if something in the setup changes (e.g. some unexpected breaking change in pyinstrument).

I'm also in favor of this smoke test. After that, we should be good to merge.