feat(tracing): OTel resource enrichment, semconv HTTP attributes, cached tracers

[Copilot]

Applies the quick-win improvements from the go-fan OTel module review: richer resource metadata, stable semconv constants for HTTP span attributes, and cached tracers at construction time.

Resource improvements (internal/tracing/provider.go)

res, err := resource.New(ctx,
    resource.WithTelemetrySDK(),                          // adds otel.library.name/version
    resource.WithSchemaURL(semconv.SchemaURL),            // OTel spec compliance
    resource.WithAttributes(
        semconv.ServiceName(serviceName),
        semconv.ServiceVersion(version.Get()),            // deployment-aware tracing
    ),
    resource.WithProcessPID(),
    resource.WithHost(),
)

Semconv HTTP attribute constants

Replaced raw string attributes with stable semconv v1.26.0 constants across all instrumented files:

Before	After
attribute.String("http.method", r.Method)	semconv.HTTPRequestMethodKey.String(r.Method)
attribute.String("http.path", r.URL.Path)	semconv.URLPathKey.String(r.URL.Path)
attribute.Int("http.status_code", code)	semconv.HTTPResponseStatusCodeKey.Int(code)

Affected: internal/tracing/http.go, internal/server/http_helpers.go, internal/server/unified.go, internal/proxy/handler.go.

Cached tracers at construction

UnifiedServer and proxyHandler previously called tracing.Tracer() (→ otel.Tracer(...)) on every request. Both now cache the tracer at construction via a tracer oteltrace.Tracer field, with a getTracer() nil-safe fallback to keep existing tests (which construct these structs directly) working without modification.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: /tmp/go-build2146563392/b510/launcher.test /tmp/go-build2146563392/b510/launcher.test -test.testlogfile=/tmp/go-build2146563392/b510/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true 6563392/b203/_pk-p ache/go/1.25.8/xgo.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp bin/as -p b/gh-aw-mcpg/int-atomic -lang=go1.25 /opt/hostedtoolc-buildtags go_.�� otlptrace/otlptr-errorsas -trimpath x_amd64/compile -p vendor/golang.ordocker-cli-plugin-metadata -lang=go1.25 x_amd64/compile (dns block)
  • Triggering command: /tmp/go-build4139057404/b514/launcher.test /tmp/go-build4139057404/b514/launcher.test -test.testlogfile=/tmp/go-build4139057404/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s /home/REDACTED/.cache/go-build/05/05ba880d21430c45c3563656362c54dda898a477387de95da38a5d091bd8bbf6-d /tmp/go-build2146563392/b392/_pkg_.a -trimpath (dns block)
• invalid-host-that-does-not-exist-12345.com
  • Triggering command: /tmp/go-build2146563392/b492/config.test /tmp/go-build2146563392/b492/config.test -test.testlogfile=/tmp/go-build2146563392/b492/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true 6563392/b163/_pk-p .cfg x_amd64/vet (dns block)
  • Triggering command: /tmp/go-build4139057404/b496/config.test /tmp/go-build4139057404/b496/config.test -test.testlogfile=/tmp/go-build4139057404/b496/testlog.txt -test.paniconexit0 -test.timeout=10m0s -I aw-mcpg/internal/difc/agent.go aw-mcpg/internal/difc/capabilities.go ache/go/1.25.8/x64/pkg/tool/linux_amd64/vet --gdwarf-5 --64 -o ache/go/1.25.8/x64/pkg/tool/linux_amd64/vet -o /tmp/go-build2146563392/b370/_pkg_.a -trimpath 6563392/b378/vet.cfg -p google.golang.or/tmp/go-build3569075202/b428/vet.cfg -lang=go1.24 /opt/hostedtoolcache/go/1.25.8/x64/pkg/tool/linu1 (dns block)
• nonexistent.local
  • Triggering command: /tmp/go-build2146563392/b510/launcher.test /tmp/go-build2146563392/b510/launcher.test -test.testlogfile=/tmp/go-build2146563392/b510/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true 6563392/b203/_pk-p ache/go/1.25.8/xgo.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp bin/as -p b/gh-aw-mcpg/int-atomic -lang=go1.25 /opt/hostedtoolc-buildtags go_.�� otlptrace/otlptr-errorsas -trimpath x_amd64/compile -p vendor/golang.ordocker-cli-plugin-metadata -lang=go1.25 x_amd64/compile (dns block)
  • Triggering command: /tmp/go-build4139057404/b514/launcher.test /tmp/go-build4139057404/b514/launcher.test -test.testlogfile=/tmp/go-build4139057404/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s /home/REDACTED/.cache/go-build/05/05ba880d21430c45c3563656362c54dda898a477387de95da38a5d091bd8bbf6-d /tmp/go-build2146563392/b392/_pkg_.a -trimpath (dns block)
• slow.example.com
  • Triggering command: /tmp/go-build2146563392/b510/launcher.test /tmp/go-build2146563392/b510/launcher.test -test.testlogfile=/tmp/go-build2146563392/b510/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true 6563392/b203/_pk-p ache/go/1.25.8/xgo.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp bin/as -p b/gh-aw-mcpg/int-atomic -lang=go1.25 /opt/hostedtoolc-buildtags go_.�� otlptrace/otlptr-errorsas -trimpath x_amd64/compile -p vendor/golang.ordocker-cli-plugin-metadata -lang=go1.25 x_amd64/compile (dns block)
  • Triggering command: /tmp/go-build4139057404/b514/launcher.test /tmp/go-build4139057404/b514/launcher.test -test.testlogfile=/tmp/go-build4139057404/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s /home/REDACTED/.cache/go-build/05/05ba880d21430c45c3563656362c54dda898a477387de95da38a5d091bd8bbf6-d /tmp/go-build2146563392/b392/_pkg_.a -trimpath (dns block)
• this-host-does-not-exist-12345.com
  • Triggering command: /tmp/go-build2146563392/b519/mcp.test /tmp/go-build2146563392/b519/mcp.test -test.testlogfile=/tmp/go-build2146563392/b519/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true /grpc_binarylog_v1/binarylog.pb.go .cfg x_amd64/compile -o (dns block)
  • Triggering command: /tmp/go-build4139057404/b523/mcp.test /tmp/go-build4139057404/b523/mcp.test -test.testlogfile=/tmp/go-build4139057404/b523/testlog.txt -test.paniconexit0 -test.timeout=10m0s -ato�� ry=1 8 x_amd64/vet -errorsas -ifaceassert -nilfunc x_amd64/vet -ato�� -bool -buildtags x_amd64/vet -errorsas -ifaceassert -nilfunc x_amd64/vet (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[Copilot]

Pull request overview

Enhances the gateway’s OpenTelemetry tracing by enriching OTEL resources, standardizing HTTP span attributes on stable semantic-convention constants, and reducing per-request overhead by caching tracers on server/handler construction.

Changes:

• Enrich OTEL resource with SDK metadata, schema URL, and service.version.
• Replace raw "http.*" attribute strings with semconv/v1.26.0 constants for method/path/status.
• Cache oteltrace.Tracer instances in UnifiedServer and proxyHandler to avoid repeated otel.Tracer(...) calls.

Show a summary per file

File	Description
internal/tracing/provider.go	Adds SDK/schema/service-version resource enrichment during provider init.
internal/tracing/http.go	Uses semconv HTTP method + URL path keys in the generic HTTP wrapper.
internal/server/unified.go	Caches tracer; switches HTTP status attribute to semconv.
internal/server/http_helpers.go	Uses semconv HTTP method + URL path keys in server HTTP middleware.
internal/proxy/proxy.go	Constructs proxyHandler with a cached tracer.
internal/proxy/handler.go	Adds cached tracer + semconv keys for path/status within proxy spans.

Copilot's findings

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Comments suppressed due to low confidence (1)

internal/proxy/handler.go:205

• This span attribute uses semconv.URLPathKey but path may include the query string (it is forwarded upstream as fullPath). url.path should not contain ?query=...; use the raw path (no query) for URLPathKey and optionally capture query/full URL via the appropriate semconv keys.

	fwdCtx, fwdSpan := h.getTracer().Start(ctx, "proxy.backend.forward",
		oteltrace.WithAttributes(
			semconv.URLPathKey.String(path),
			attribute.String("tool.name", toolName),
		),

• Files reviewed: 6/6 changed files
• Comments generated: 2