Handle JSON-form GH_AW_OTLP_ENDPOINTS in tracing provider and isolate inherited env in provider tests

[Copilot]

The smoke OTel tracing workflow sets GH_AW_OTLP_ENDPOINTS as a JSON array, but the tracing resolver only handled comma-separated URLs. That caused invalid fan-out endpoints to be constructed, which in turn broke noop-provider expectations and redirected header tests away from their local collectors.

• Tracing config parsing

  • Teach GH_AW_OTLP_ENDPOINTS resolution to accept either:
    • comma-separated endpoint URLs, or
    • a JSON array of objects with url and optional headers
  • Ignore empty entries and invalid JSON payloads instead of turning them into malformed OTLP endpoints.

• Exporter construction

  • Preserve existing shared header behavior from OTEL_EXPORTER_OTLP_HEADERS / config.
  • Merge per-endpoint headers from JSON entries into each exporter, with endpoint-specific values taking precedence.

• Regression coverage

  • Add resolver coverage for JSON arrays, empty arrays, invalid JSON, and endpoint normalization.
  • Add direct coverage for OTLP header merging behavior.
  • Explicitly clear inherited GH_AW_OTLP_ENDPOINTS in the affected provider tests so noop and local-collector cases do not depend on ambient workflow env.

// Existing form
GH_AW_OTLP_ENDPOINTS=http://collector-a:4318,https://collector-b.example.com

// Newly supported workflow form
GH_AW_OTLP_ENDPOINTS=[{"url":"https://collector.example.com/otlp","headers":"Authorization=******"}]

[lpcox]

@copilot resolve the merge conflicts in this pull request

[Copilot]

Pull request overview

This PR updates the tracing configuration and provider initialization to properly support GH_AW_OTLP_ENDPOINTS when it is provided as a JSON array (as used by the smoke OTel tracing workflow), including per-endpoint header overrides, and adds regression tests around parsing and header merging.

Changes:

• Extend GH_AW_OTLP_ENDPOINTS parsing to accept either comma-separated URLs or a JSON array of {url, headers} entries, skipping empty entries and treating invalid JSON as “unset”.
• Update OTLP exporter construction to merge shared headers with endpoint-specific headers (endpoint-specific values take precedence).
• Add regression tests for JSON endpoint parsing, endpoint normalization, header parsing/merging, and reduce test coupling to inherited GH_AW_OTLP_ENDPOINTS in some provider tests.

Show a summary per file

File	Description
internal/tracing/config_resolver.go	Adds JSON-array parsing for GH_AW_OTLP_ENDPOINTS, introduces extraEndpointConfig, and normalizes endpoints consistently.
internal/tracing/provider.go	Switches provider fan-out selection to extraEndpointConfig and merges shared + per-endpoint OTLP headers for exporter creation.
internal/tracing/resolve_endpoint_test.go	Adds coverage for JSON-array parsing, invalid/empty JSON behavior, and normalization behavior.
internal/tracing/provider_test.go	Adds a test for JSON per-endpoint headers and clears inherited GH_AW_OTLP_ENDPOINTS in a couple of tests.
internal/tracing/provider_internal_test.go	Adds unit tests for mergeOTLPHeaders behavior (override + nil/empty handling).

Copilot's findings

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• Files reviewed: 5/5 changed files
• Comments generated: 1

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved. The only conflict was in internal/tracing/provider_test.go — both sides had the same t.Setenv("GH_AW_OTLP_ENDPOINTS", "") call; origin/main had added explanatory comments alongside it. I kept the commented versions from main in both locations.

[lpcox]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved. The conflict was again in internal/tracing/provider.go — our branch had the new mergeOTLPHeaders function while origin/main had added a CachedTracer struct at the same location. I kept both in the merged commit (8a9fdd60).