feat(otlp-proto): pre-compile proto files

[legendecas]

Which problem is this PR solving?

Precompile proto files to JS source code and get rid of runtime code generation. Also, this allows exporting traces and metrics in one process simultaneously by not caching the ExportRequestProto type.

This doesn't change how otlp-grpc-exporter loads proto files as https://github.com/grpc/grpc-node/tree/master/packages/proto-loader requires raw proto files to load service definitions.

Fixes #515

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

The existing tests should cover this change.

Checklist:

• Followed the style guidelines of this project

[codecov]

Codecov Report

Merging #3098 (6620fd8) into main (9ac9976) will decrease coverage by 0.96%.
The diff coverage is n/a.

❗ Current head 6620fd8 differs from pull request most recent head 8b98760. Consider uploading reports for the commit 8b98760 to get more accurate results

@@            Coverage Diff             @@
##             main    #3098      +/-   ##
==========================================
- Coverage   93.06%   92.09%   -0.97%     
==========================================
  Files         188       82     -106     
  Lines        6248     2405    -3843     
  Branches     1313      520     -793     
==========================================
- Hits         5815     2215    -3600     
+ Misses        433      190     -243     

Impacted Files	Coverage Δ
...s/opentelemetry-core/src/platform/node/sdk-info.ts	0.00% <0.00%> (-100.00%)	⬇️
...opentelemetry-core/src/platform/node/globalThis.ts	0.00% <0.00%> (-100.00%)	⬇️
...pentelemetry-core/src/platform/node/performance.ts	0.00% <0.00%> (-100.00%)	⬇️
...emetry-api-metrics/src/platform/node/globalThis.ts	0.00% <0.00%> (-100.00%)	⬇️
...lemetry-resources/src/detectors/ProcessDetector.ts	31.81% <0.00%> (-68.19%)	⬇️
...perimental/packages/otlp-exporter-base/src/util.ts	79.41% <0.00%> (-17.65%)	⬇️
...ckages/opentelemetry-exporter-zipkin/src/zipkin.ts	84.48% <0.00%> (-15.52%)	⬇️
...lemetry-resources/src/detectors/BrowserDetector.ts	93.33% <0.00%> (-6.67%)	⬇️
...emetry-sdk-metrics-base/src/export/MetricReader.ts
...sync-hooks/src/AbstractAsyncHooksContextManager.ts
... and 104 more

[dyladan]

Can you document how to regenerate the js when we need to update? A script would be even better.

[vmarchaud]

Can you document how to regenerate the js when we need to update? A script would be even better.

I believe the script is there: https://github.com/open-telemetry/opentelemetry-js/pull/3098/files#diff-90a1f9aebed9b5b6edbb022c2bb5afb203e3317af67429a27ac9f63fb75bcb13R1 and its run automatically when we run lerna run compile

[dyladan]

Can you document how to regenerate the js when we need to update? A script would be even better.

I believe the script is there: #3098 (files) and its run automatically when we run lerna run compile

Ahh i just missed it

[legendecas]

Yeah, the generation is automatic as registered in the package.json scripts and there is no need to manually run the script to compile it.

[dyladan]

Do we know how this affects final bundle size in browser?

[legendecas]

Do we know how this affects final bundle size in browser?

With a naïve comparison, code generated with this PR reduces the bundle size to ~300kb (bundled and minified with @vercel/ncc) from ~310kb (~220kb JS source code + ~90kb proto files).

[dyladan]

Wow both quite large. Ok thanks for the stats

[dyladan]

This seems ok to merge when you're happy with it.