Add flag to OCB to generate component config JSON schema

[pavolloffay]

Description

This PR adds collector component JSON schema generation to OCB

      --generate-schema    Experimental: Whether builder should generate JSON schemas for component configs (default false)

Example schema generation is here: open-telemetry/opentelemetry-collector-releases#1299

  The schema generator uses static analysis (not runtime reflection) to analyze Go component packages and generate JSON schemas for their configuration types.

  Architecture

  ┌─────────────────────────────────────────────────────────────────┐
  │                    GenerateAndCompile()                         │
  │                  internal/builder/main.go                       │
  └─────────────────────────┬───────────────────────────────────────┘
                            │ if cfg.GenerateSchema
                            ▼
  ┌─────────────────────────────────────────────────────────────────┐
  │                    GenerateSchemas()                            │
  │  - Creates PackageAnalyzer & SchemaGenerator                    │
  │  - Iterates over Extensions, Receivers, Processors, etc.        │
  │  - Calls generator.GenerateSchema() for each component          │
  └─────────────────────────┬───────────────────────────────────────┘
                            ▼
  ┌─────────────────────────────────────────────────────────────────┐
  │                internal/schemagen/                              │
  ├─────────────────────────────────────────────────────────────────┤
  │  analyzer.go    │ Loads packages, finds Config types via AST   │
  │  generator.go   │ Converts Go types → JSON Schema              │
  │  comments.go    │ Extracts doc comments for descriptions       │
  └─────────────────────────────────────────────────────────────────┘

#14288 is alternative solution which adds the schema generation to mdatagen

Link to tracking issue

Fixes #9769

Testing

• Unit tests
• Example schema generation Do not merge, JSON schemas examples opentelemetry-collector-releases#1299

Documentation

[codecov]

Codecov Report

❌ Patch coverage is 81.32075% with 99 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.01%. Comparing base (2e5bb6d) to head (73ebdfd).
⚠️ Report is 81 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/builder/internal/schemagen/generator.go	75.20%	44 Missing and 18 partials ⚠️
cmd/builder/internal/schemagen/analyzer.go	81.35%	11 Missing and 11 partials ⚠️
cmd/builder/internal/builder/main.go	65.90%	8 Missing and 7 partials ⚠️

❌ Your patch status has failed because the patch coverage (81.32%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14261      +/-   ##
==========================================
- Coverage   92.15%   92.01%   -0.15%     
==========================================
  Files         668      672       +4     
  Lines       41513    42045     +532     
==========================================
+ Hits        38257    38687     +430     
- Misses       2219     2284      +65     
- Partials     1037     1074      +37     

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[codspeed-hq]

CodSpeed Performance Report

Merging #14261 will not alter performance

_{Comparing pavolloffay:ocb-component-schema (73ebdfd) with main (b31ddb9)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 59 untouched
⏩ 20 skipped¹

Footnotes

1. 20 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[niwoerner]

Food for thought: We could think about capturing the default values of the config through calling the CreateDefaultConfig function and reflecting the values of it.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.