Merge pull request #10 from mercari/otel-gcp-2

Improve OpenTelemetry tracing

Author: south-mer

server/handler/fetcher.go

@@ -24,6 +24,9 @@ import (
 	"github.com/google/go-github/v72/github"
 	"github.com/palantir/go-githubapp/appconfig"
 	"github.com/palantir/policy-bot/policy"
+	"github.com/palantir/policy-bot/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
 	"gopkg.in/yaml.v2"
 )
 
@@ -41,6 +44,14 @@ type ConfigFetcher struct {
 }
 
 func (cf *ConfigFetcher) ConfigForRepositoryBranch(ctx context.Context, client *github.Client, owner, repository, branch string) FetchedConfig {
+	ctx, span := tracing.Tracer.Start(ctx, "ConfigFetcher.ConfigForRepositoryBranch",
+		trace.WithAttributes(
+			attribute.String("owner", owner),
+			attribute.String("repository", repository),
+			attribute.String("branch", branch),
+		))
+	defer span.End()
+
 	retries := 0
 	delay := 1 * time.Second
 	for {

server/otel/handler.go

@@ -0,0 +1,52 @@
+// Copyright 2025 Palantir Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otel
+
+import (
+	"context"
+
+	"github.com/palantir/go-githubapp/githubapp"
+	"github.com/palantir/policy-bot/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+type traceHandler struct {
+	handler githubapp.EventHandler
+}
+
+var _ githubapp.EventHandler = (*traceHandler)(nil)
+
+func (h *traceHandler) Handles() []string {
+	return h.handler.Handles()
+}
+
+func (h *traceHandler) Handle(ctx context.Context, eventType, deliveryID string, payload []byte) error {
+	ctx, span := tracing.Tracer.Start(ctx, "githubapp.EventHandler.Handle",
+		trace.WithAttributes(
+			attribute.String("event_type", eventType),
+			attribute.String("delivery_id", deliveryID),
+		))
+	defer span.End()
+
+	if err := h.handler.Handle(ctx, eventType, deliveryID, payload); err != nil {
+		span.RecordError(err)
+	}
+	return nil
+}
+
+func Trace(handler githubapp.EventHandler) githubapp.EventHandler {
+	return &traceHandler{handler: handler}
+}

server/server.go

@@ -104,7 +104,13 @@ func New(ctx context.Context, c *Config) (*Server, error) {
 		registry := metrics.NewPrefixedRegistry("policybot.")
 		middlewares := append(
 			[]func(http.Handler) http.Handler{
-				func(h http.Handler) http.Handler { return otelhttp.NewHandler(h, "policy-bot") },
+				func(h http.Handler) http.Handler {
+					return otelhttp.NewHandler(h, "policy-bot", otelhttp.WithFilter(func(r *http.Request) bool {
+						skip := r.URL.Path == "/" || r.URL.Path == "/api/github/hook" ||
+							strings.HasPrefix(r.URL.Path, "/static")
+						return !skip
+					}))
+				},
 			},
 			baseapp.DefaultMiddleware(logger, registry)...,
 		)
@@ -218,14 +224,14 @@ func New(ctx context.Context, c *Config) (*Server, error) {
 
 	dispatcher := githubapp.NewEventDispatcher(
 		[]githubapp.EventHandler{
-			&handler.Installation{Base: basePolicyHandler},
-			&handler.MergeGroup{Base: basePolicyHandler},
-			&handler.PullRequest{Base: basePolicyHandler},
-			&handler.PullRequestReview{Base: basePolicyHandler},
-			&handler.IssueComment{Base: basePolicyHandler},
-			&handler.Status{Base: basePolicyHandler},
-			&handler.CheckRun{Base: basePolicyHandler},
-			&handler.WorkflowRun{Base: basePolicyHandler},
+			policybototel.Trace(&handler.Installation{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.MergeGroup{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.PullRequest{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.PullRequestReview{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.IssueComment{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.Status{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.CheckRun{Base: basePolicyHandler}),
+			policybototel.Trace(&handler.WorkflowRun{Base: basePolicyHandler}),
 		},
 		c.Github.App.WebhookSecret,
 		githubapp.WithErrorCallback(githubapp.MetricsErrorCallback(base.Registry())),