scripts/decode-resp: decode flamebearer response for debugging

[iOliverNguyen]

This PR adds scripts/decode-resp for decoding response.

Decode response from pyroscope, for debugging

Usage: decode-resp -file <response.json>
  where <response.json> is the body response from /render API
  example: http://localhost:4040/render?from=now-1h&until=now&name=pyroscope.server.alloc_objects{}&max-nodes=1024&format=json

Flags:
  -file string
    	path to response file (required)
  -out string
    	name of output file (default to NAME.out.EXT)

[petethepig]

Please use ginkgo + gomega for testing stuff, here's an example: https://github.com/pyroscope-io/pyroscope/blob/main/pkg/storage/storage_test.go#L228

[iOliverNguyen]

I see. Will change that.

[iOliverNguyen]

I updated the test with ginkgo + gomega.

[petethepig]

This looks good. My only question is why do we need it. Can you explain the usescase?

[iOliverNguyen]

As a new contributor, I need to understand the response structure (especially levels with delta encoding), so I created this script:

• This will help other new contributors when joining the project, to easily decoding/understanding the response (with delta encoding).
• Also, when we add new data or modify the structure, as discussed in implementing the diff view, this will help to debug.

[codecov]

Codecov Report

Merging #284 (0994fe7) into main (fada901) will decrease coverage by 0.21%.
The diff coverage is 32.66%.

@@            Coverage Diff             @@
##             main     #284      +/-   ##
==========================================
- Coverage   54.21%   54.01%   -0.20%     
==========================================
  Files          89       91       +2     
  Lines        3638     3687      +49     
==========================================
+ Hits         1972     1991      +19     
- Misses       1466     1496      +30     
  Partials      200      200              

Impacted Files	Coverage Δ
scripts/decode-resp/main.go	0.00% <0.00%> (ø)
scripts/decode-resp/decode.go	100.00% <100.00%> (ø)
pkg/agent/session.go	66.40% <0.00%> (+2.46%)	⬆️

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