OpenFeature: Add tracing to feature flags service (#111895)

* Add tracing to feature flags service * Apply review feedback * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Apply suggestion from @hairyhenderson Co-authored-by: Dave Henderson <dave.henderson@grafana.com> * Fix issues --------- Co-authored-by: Dave Henderson <dave.henderson@grafana.com>
2025-10-06 09:16:29 +02:00
parent 64a483d112
commit 843956e795
3 changed files with 63 additions and 10 deletions
@@ -2,6 +2,7 @@ package ofrep

 import (
 	"bytes"
+	"context"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/json"
@@ -14,14 +15,21 @@ import (
 	"strconv"

 	"github.com/grafana/grafana/pkg/cmd/grafana-cli/logger"
+	"github.com/grafana/grafana/pkg/infra/tracing"
 	"github.com/grafana/grafana/pkg/util/proxyutil"

 	goffmodel "github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/model"
 )

-func (b *APIBuilder) proxyAllFlagReq(isAuthedUser bool, w http.ResponseWriter, r *http.Request) {
+func (b *APIBuilder) proxyAllFlagReq(ctx context.Context, isAuthedUser bool, w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(ctx, "ofrep.proxy.evalAllFlags")
+	defer span.End()
+
+	r = r.WithContext(ctx)
+
 	proxy, err := b.newProxy(ofrepPath)
 	if err != nil {
+		err = tracing.Error(span, err)
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
@@ -61,9 +69,15 @@ func (b *APIBuilder) proxyAllFlagReq(isAuthedUser bool, w http.ResponseWriter, r
 	proxy.ServeHTTP(w, r)
 }

-func (b *APIBuilder) proxyFlagReq(flagKey string, isAuthedUser bool, w http.ResponseWriter, r *http.Request) {
+func (b *APIBuilder) proxyFlagReq(ctx context.Context, flagKey string, isAuthedUser bool, w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(ctx, "ofrep.proxy.evalFlag")
+	defer span.End()
+
+	r = r.WithContext(ctx)
+
 	proxy, err := b.newProxy(path.Join(ofrepPath, flagKey))
 	if err != nil {
+		err = tracing.Error(span, err)
 		b.logger.Error("Failed to create proxy", "key", flagKey, "error", err)
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -10,6 +10,9 @@ import (
 	"net/url"

 	"github.com/gorilla/mux"
+	"github.com/grafana/grafana/pkg/infra/tracing"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -31,6 +34,8 @@ var _ builder.APIGroupBuilder = (*APIBuilder)(nil)
 var _ builder.APIGroupRouteProvider = (*APIBuilder)(nil)
 var _ builder.APIGroupVersionProvider = (*APIBuilder)(nil)

+var tracer = otel.Tracer("github.com/grafana/grafana/pkg/registry/apis/ofrep")
+
 const ofrepPath = "/ofrep/v1/evaluate/flags"

 const namespaceMismatchMsg = "rejecting request with namespace mismatch"
@@ -240,7 +245,13 @@ func (b *APIBuilder) GetAPIRoutes(gv schema.GroupVersion) *builder.APIRoutes {
 }

 func (b *APIBuilder) oneFlagHandler(w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(r.Context(), "ofrep.handler.evalFlag")
+	defer span.End()
+
+	r = r.WithContext(ctx)
+
 	if !b.validateNamespace(r) {
+		_ = tracing.Errorf(span, namespaceMismatchMsg)
 		b.logger.Error(namespaceMismatchMsg)
 		http.Error(w, namespaceMismatchMsg, http.StatusUnauthorized)
 		return
@@ -248,42 +259,54 @@ func (b *APIBuilder) oneFlagHandler(w http.ResponseWriter, r *http.Request) {

 	flagKey := mux.Vars(r)["flagKey"]
 	if flagKey == "" {
+		_ = tracing.Errorf(span, "flagKey parameter is required")
 		http.Error(w, "flagKey parameter is required", http.StatusBadRequest)
 		return
 	}

+	span.SetAttributes(attribute.String("flag_key", flagKey))
+
 	isAuthedReq := b.isAuthenticatedRequest(r)
+	span.SetAttributes(attribute.Bool("authenticated", isAuthedReq))

 	// Unless the request is authenticated, we only allow public flags evaluations
 	if !isAuthedReq && !isPublicFlag(flagKey) {
+		_ = tracing.Errorf(span, "unauthorized to evaluate flag: %s", flagKey)
 		b.logger.Error("Unauthorized to evaluate flag", "flagKey", flagKey)
 		http.Error(w, "unauthorized to evaluate flag", http.StatusUnauthorized)
 		return
 	}

 	if b.providerType == setting.GOFFProviderType {
-		b.proxyFlagReq(flagKey, isAuthedReq, w, r)
+		b.proxyFlagReq(ctx, flagKey, isAuthedReq, w, r)
 		return
 	}

-	b.evalFlagStatic(flagKey, w, r)
+	b.evalFlagStatic(ctx, flagKey, w)
 }

 func (b *APIBuilder) allFlagsHandler(w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(r.Context(), "ofrep.handler.evalAllFlags")
+	defer span.End()
+
+	r = r.WithContext(ctx)
+
 	if !b.validateNamespace(r) {
+		_ = tracing.Errorf(span, namespaceMismatchMsg)
 		b.logger.Error(namespaceMismatchMsg)
 		http.Error(w, namespaceMismatchMsg, http.StatusUnauthorized)
 		return
 	}

 	isAuthedReq := b.isAuthenticatedRequest(r)
+	span.SetAttributes(attribute.Bool("authenticated", isAuthedReq))

 	if b.providerType == setting.GOFFProviderType {
-		b.proxyAllFlagReq(isAuthedReq, w, r)
+		b.proxyAllFlagReq(ctx, isAuthedReq, w, r)
 		return
 	}

-	b.evalAllFlagsStatic(isAuthedReq, w, r)
+	b.evalAllFlagsStatic(ctx, isAuthedReq, w)
 }

 func writeResponse(statusCode int, result any, logger log.Logger, w http.ResponseWriter) {
@@ -1,19 +1,28 @@
 package ofrep

 import (
+	"context"
 	"net/http"

+	"github.com/grafana/grafana/pkg/infra/tracing"
 	goffmodel "github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/model"
+	"go.opentelemetry.io/otel/attribute"
 )

-func (b *APIBuilder) evalAllFlagsStatic(isAuthedUser bool, w http.ResponseWriter, r *http.Request) {
-	result, err := b.staticEvaluator.EvalAllFlags(r.Context())
+func (b *APIBuilder) evalAllFlagsStatic(ctx context.Context, isAuthedUser bool, w http.ResponseWriter) {
+	_, span := tracer.Start(ctx, "ofrep.static.evalAllFlags")
+	defer span.End()
+
+	result, err := b.staticEvaluator.EvalAllFlags(ctx)
 	if err != nil {
+		err = tracing.Error(span, err)
 		b.logger.Error("Failed to evaluate all static flags", "error", err)
 		http.Error(w, "failed to evaluate flags", http.StatusInternalServerError)
 		return
 	}

+	span.SetAttributes(attribute.Int("total_flags_count", len(result.Flags)))
+
 	if !isAuthedUser {
 		var publicOnly []goffmodel.OFREPFlagBulkEvaluateSuccessResponse

@@ -24,14 +33,21 @@ func (b *APIBuilder) evalAllFlagsStatic(isAuthedUser bool, w http.ResponseWriter
 		}

 		result.Flags = publicOnly
+		span.SetAttributes(attribute.Int("public_flags_count", len(publicOnly)))
 	}

 	writeResponse(http.StatusOK, result, b.logger, w)
 }

-func (b *APIBuilder) evalFlagStatic(flagKey string, w http.ResponseWriter, r *http.Request) {
-	result, err := b.staticEvaluator.EvalFlag(r.Context(), flagKey)
+func (b *APIBuilder) evalFlagStatic(ctx context.Context, flagKey string, w http.ResponseWriter) {
+	_, span := tracer.Start(ctx, "ofrep.static.evalFlag")
+	defer span.End()
+
+	span.SetAttributes(attribute.String("flag_key", flagKey))
+
+	result, err := b.staticEvaluator.EvalFlag(ctx, flagKey)
 	if err != nil {
+		err = tracing.Error(span, err)
 		b.logger.Error("Failed to evaluate static flag", "key", flagKey, "error", err)
 		http.Error(w, "failed to evaluate flag", http.StatusInternalServerError)
 		return