feat: config validation improvements, wire DebugLogInterceptor

[ankurs]

Summary

Config validation (ROADMAP 4.1):

• TLS file existence check via os.Stat when both cert and key are set
• OTLP endpoint host:port format validation via net.SplitHostPort
• Log level validation against known levels (error, warn, warning, info, debug)
• Timeout vs shutdown duration sanity warning

DebugLogInterceptor wiring:

• Add DisableDebugLogInterceptor bool and DebugLogHeaderName string config fields
• Wire to interceptors in processConfig()
• Update getCustomHeaderMatcher to variadic headers — forwards debug log header from HTTP to gRPC metadata alongside trace header

Goroutine leak detection:

• Add goleak.VerifyTestMain with documented ignores for third-party singletons

Depends on: go-coldbrew/interceptors#38 (DebugLogInterceptor)

Test plan

• 4 new config validation tests (TLS files, OTLP format, log level, timeout sanity)
• All existing core tests pass
• make test and make lint clean (tested with local replace directive for interceptors)

Summary by CodeRabbit

Release Notes

• New Features

  • Added configuration options to disable debug logging and customize the debug log header name.
  • Enhanced startup validation with warnings for missing TLS files, invalid OTLP endpoint format, unrecognized log levels, and timeout conflicts.

• Improvements

  • Improved HTTP to gRPC header forwarding to support multiple custom headers.

• Dependencies

  • Updated core dependencies to latest versions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8253bf4e-92a6-440c-aa6f-e3cc336df329

📥 Commits

Reviewing files that changed from the base of the PR and between 22416eb and 01f2c6a.

⛔ Files ignored due to path filters (1)

• go.sum is excluded by !**/*.sum

📒 Files selected for processing (6)

• config/config.go
• config/config_test.go
• core.go
• core_test.go
• go.mod
• goleak_test.go

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📝 Walkthrough

Walkthrough

This PR extends the configuration system with new interceptor and logging controls, adds comprehensive startup validation for TLS files, OTLP endpoint format, log levels, and gRPC timeout settings. It updates header matching logic to support multiple headers and adds goleak dependency for goroutine leak detection in tests.

Changes

Cohort / File(s)	Summary
Configuration Fields & Validation config/config.go, config/config_test.go	Added DisableDebugLogInterceptor and DebugLogHeaderName config fields; extended Validate() to check TLS file existence via os.Stat, validate OTLP endpoint format using net.SplitHostPort, verify log level against recognized values, and warn when gRPC server timeout exceeds shutdown duration. Comprehensive test coverage added for all new validation paths.
Core Interceptor & Header Matching core.go, core_test.go	Updated HTTP→gRPC header matcher to support variadic headers and exact-match multiple header names; configured debug log interceptor initialization based on new config fields; added test coverage for multi-header matching behavior.
Dependencies & Test Infrastructure go.mod, goleak_test.go	Updated minor/patch versions for go-coldbrew packages (errors, interceptors, log, tracing) and added new direct dependency go.uber.org/goleak v1.3.0; added TestMain in core package to configure goroutine leak detection with ignores for known background goroutines from gRPC, OpenTelemetry, Sentry, and rollbar-go.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• feat: native stats/opentelemetry + OTEL metrics + OpenTracing removal #71: Modifies the same config.Config struct and extends Validate() with startup warnings.
• perf: configurable HTTP compression, NR auto-disable, response time log config #58: Both PRs alter Config struct for interceptor/logging controls and update interceptor wiring with additional configuration parameters.
• feat: wire GRPC_SERVER_DEFAULT_TIMEOUT_IN_SECONDS config #73: Both PRs add GRPCServerDefaultTimeoutInSeconds config field and wire it into interceptor/server behavior with validation logic.

Suggested reviewers

• vestor
• fajran
• kevinjom
• svetha-cvl

Poem

🐰 twitches whiskers with delight
Headers multiply, validation shines bright,
Debug logs leap where they should go,
Goleak watches goroutines flow—
Config wisdom flows just right! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the two main objectives: configuration validation improvements and DebugLogInterceptor wiring, matching the primary changes across config and core files.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/config-validation-debug-interceptor

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[Copilot]

Pull request overview

This PR improves startup-time configuration validation, wires the new DebugLogInterceptor controls into the core interceptor setup, and adds goroutine leak detection for the core package test suite.

Changes:

• Added additional Config.Validate() checks (TLS file existence, OTLP host:port formatting, log level validation, and timeout vs shutdown sanity warning) plus new unit tests.
• Wired DisableDebugLogInterceptor / DebugLogHeaderName into processConfig() and forwarded the debug header from HTTP gateway to gRPC metadata via an updated header matcher.
• Added goleak.VerifyTestMain for core tests and introduced go.uber.org/goleak as a dependency.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
goleak_test.go	Adds a TestMain to verify goroutine leaks with documented ignores.
go.mod	Adds the go.uber.org/goleak dependency.
core.go	Wires DebugLogInterceptor config and forwards debug header via grpc-gateway header matcher.
config/config.go	Adds new config fields and validation warnings for common misconfigurations.
config/config_test.go	Adds tests covering the new config validation behavior.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

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