feat(otel): bootstrap OTel SDK with autoexport/autoprop

[bramwelt]

Summary

• Add pkg/utils/otel.go — bootstraps OpenTelemetry SDK using autoexport/autoprop packages, eliminating manual exporter boilerplate
• Add pkg/utils/otel_test.go — tests for config, sampler, and SDK init (uses OTEL_*_EXPORTER=none so no external deps required)
• Call SetupOTelSDKWithConfig from main.go after InitStructureLogConfig(), with graceful 25s shutdown timeout
• Enable OTEL_SERVICE_NAME in charts/lfx-v2-voting-service/values.yaml; all other exporter/endpoint/sampler config delegated to ArgoCD overrides via standard OTEL_* env vars

The service already had otelhttp.NewHandler and slogotel.OtelHandler wired, but no SDK initialization — so no TracerProvider was registered and no spans were exported. This fixes that.

Design decisions

• autoexport/autoprop — matches meeting-service migration; zero exporter boilerplate, standard OTEL_* env vars control everything
• Only OTEL_SERVICE_NAME in chart defaults — endpoint, protocol, sampler set in ArgoCD production overrides, keeping chart safe for local dev (no exporter configured = no-op)

Test plan

• make build — passes
• make test (pkg/utils) — all OTel tests pass; OTEL_*_EXPORTER=none used so no external deps needed
• Pre-existing race in TestEventProcessor_Start — confirmed present on main before this change, unrelated

Closes LFXV2-1735

🤖 Generated with Claude Code

[bramwelt]

This license expression (BSD-3-Clause AND LicenseRef-scancode-google-patent-license-golang) is the standard Go patent grant that accompanies all Google-contributed Go dependencies. It is not a code issue — it requires the license policy allowlist to be updated to permit the LicenseRef-scancode-google-patent-license-golang identifier. Leaving this thread open for the policy team to action.

[Copilot]

Pull request overview

This PR adds first-class OpenTelemetry SDK bootstrapping to the voting service using autoexport and autoprop, so existing HTTP/log instrumentation can produce/export telemetry by registering SDK providers at startup.

Changes:

• Add pkg/utils/otel.go to initialize trace/metric/log providers and propagators via standard OTEL_* environment variables.
• Add pkg/utils/otel_test.go to validate env-driven config, sampler behavior, and SDK init/shutdown with exporters disabled.
• Initialize the OTel SDK from cmd/voting-api/main.go and set a default OTEL_SERVICE_NAME in the Helm chart values.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/utils/otel.go	New OTel SDK bootstrap utility (resource, sampler, providers, shutdown).
pkg/utils/otel_test.go	New tests covering env config, sampler parsing, and init/shutdown behavior.
cmd/voting-api/main.go	Wires OTel SDK initialization and graceful shutdown into service startup.
charts/lfx-v2-voting-service/values.yaml	Sets default OTEL_SERVICE_NAME and documents that other OTel env is overridden in ArgoCD.
go.mod	Adds required OpenTelemetry dependencies (autoexport/autoprop + SDK/log/metric).
go.sum	Adds dependency checksums for the newly introduced modules.

Comments suppressed due to low confidence (3)

pkg/utils/otel_test.go:36

• This test uses os.Setenv/os.Unsetenv instead of t.Setenv, which means environment restoration depends on the defer and can still leak when the test fails early or subtests are added. Prefer t.Setenv (and t.Cleanup for any additional restoration) for safer, race-free env handling.

	_ = os.Setenv("OTEL_SERVICE_NAME", "test-service")
	_ = os.Setenv("OTEL_SERVICE_VERSION", "1.2.3")
	defer func() {
		_ = os.Unsetenv("OTEL_SERVICE_NAME")
		_ = os.Unsetenv("OTEL_SERVICE_VERSION")
	}()

pkg/utils/otel_test.go:180

• The subtest setup unsets env vars with os.Unsetenv (no automatic restoration), which can leak state across other tests in this package when the runner has OTEL_* variables set. Prefer setting explicit empty values via t.Setenv (or saving/restoring with t.Cleanup) instead of globally unsetting.

		t.Run(tt.sampler+"_"+tt.arg, func(t *testing.T) {
			_ = os.Unsetenv("OTEL_TRACES_SAMPLER")
			_ = os.Unsetenv("OTEL_TRACES_SAMPLER_ARG")
			if tt.sampler != "" {
				t.Setenv("OTEL_TRACES_SAMPLER", tt.sampler)
			}
			if tt.arg != "" {
				t.Setenv("OTEL_TRACES_SAMPLER_ARG", tt.arg)
			}

pkg/utils/otel_test.go:216

• This test unsets OTEL_SERVICE_* via os.Unsetenv without restoring prior values, which can leak into subsequent tests in this package. Prefer t.Setenv with empty values (or save/restore with t.Cleanup) to keep test environment isolation.

	t.Setenv("OTEL_TRACES_EXPORTER", "none")
	t.Setenv("OTEL_METRICS_EXPORTER", "none")
	t.Setenv("OTEL_LOGS_EXPORTER", "none")
	_ = os.Unsetenv("OTEL_SERVICE_NAME")
	_ = os.Unsetenv("OTEL_SERVICE_VERSION")

---

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[bramwelt]

Review feedback addressed (commit 1dc95a1)

All 4 actionable copilot threads have been resolved:

Thread	Change
Empty service.version in newResource	service.version attribute is now only added when cfg.ServiceVersion != ""
Hard-coded 1s batch timeout	Removed trace.WithBatchTimeout(time.Second); SDK default (5s) used instead. "time" import removed.
os.Unsetenv without restore in tests	All os.Unsetenv/os.Setenv+defer patterns replaced with t.Setenv throughout otel_test.go. "os" import removed.
Brittle sampler Description() assertion	Replaced exact string match with strings.Contains(s.Description(), "TraceIDRatioBased")

The license compliance thread (thread 1) has been responded to but left open — it requires a policy allowlist update for LicenseRef-scancode-google-patent-license-golang, which is the standard Go patent grant and not a code issue.

[bramwelt]

Review feedback addressed

All 4 copilot review threads have been resolved in commit 1dc95a1:

Thread	Change
Empty service.version in newResource	service.version attribute only added when cfg.ServiceVersion != ""
Hard-coded 1s batch timeout	Removed trace.WithBatchTimeout(time.Second) — uses SDK default (5s). Removed unused "time" import
os.Unsetenv without restore in tests	Replaced all os.Unsetenv/os.Setenv+defer patterns with t.Setenv throughout otel_test.go. Removed "os" import
Brittle sampler Description() assertion	Replaced exact string match with strings.Contains(s.Description(), "TraceIDRatioBased")

The license compliance thread (github-license-compliance on go.mod) has been left open — it requires the policy allowlist to be updated to permit LicenseRef-scancode-google-patent-license-golang (the standard Google patent grant on Go dependencies), not a code change.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 4 comments.

[bramwelt]

Second-round review follow-up

Addressed all 4 actionable copilot[bot] threads from the second review pass (commit f4b6093):

Thread	File	Fix
service.name always set even when empty	pkg/utils/otel.go:133	Added cfg.ServiceName != "" guard, matching the existing service.version pattern
ServiceVersion doc comment inaccurate	pkg/utils/otel.go:33	Updated to (no default; caller may set from build-time ldflags)
OTEL_*_EXPORTER doc too restrictive	pkg/utils/otel.go:68	Loosened to (as supported by autoexport, e.g. "otlp", "none", "stdout")
Command-line/environment comment incorrect	cmd/voting-api/main.go:54	Changed to Environment variable

The license-compliance thread (go.mod) is left unresolved — it requires a policy allowlist update, not a code change.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

[bramwelt]

Third-round review follow-up

Addressed 2 new copilot[bot] threads (commit 8b57de3):

Thread	File	Fix
Default sampler should be parentbased_always_on per OTel spec	pkg/utils/otel.go:168	Changed default case to trace.ParentBased(trace.AlwaysSample()); added explicit "always_on" case; updated doc comment
Mixed contrib/* versions (otelhttp v0.65.0 vs others at v0.68.0)	go.mod:20	Upgraded otelhttp v0.65.0 → v0.68.0

The license-compliance thread (go.mod) remains open — policy team action required.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated no new comments.