Add otel tracer for gqlgenx (#73)

Signed-off-by: GitHub <[email protected]>

gqlgenx/oteltracing/doc.go

@@ -0,0 +1,26 @@
+// Copyright 2023 The Infratographer Authors
+//
+// 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 oteltracing provides a gqlgen middleware that adds otel tracing.
+//
+// You can use it like:
+//
+//	srv := handler.New(es)
+//	srv.Use(oteltracing.Tracer{})
+//
+// If you would like spans for every field in the response you can enable FieldSpans:
+//
+//	srv := handler.New(es)
+//	srv.Use(oteltracing.Tracer{FieldSpans: true})
+package oteltracing

gqlgenx/oteltracing/tracer.go

@@ -0,0 +1,66 @@
+package oteltracing
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/99designs/gqlgen/graphql"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+type (
+	// Tracer provides an otel tracer for gqlgen servers
+	Tracer struct {
+		// FieldSpans allow you to enable a span for each field in the response
+		FieldSpans bool
+	}
+)
+
+var _ interface {
+	graphql.HandlerExtension
+	graphql.FieldInterceptor
+} = Tracer{}
+
+var tracer = otel.Tracer("go.infratographer.com/x/gqlgenx/oteltracing")
+
+// ExtensionName returns the name of this extension
+func (Tracer) ExtensionName() string {
+	return "OpenTelemetryTracing"
+}
+
+// Validate is required to meet HandlerExtension interface
+func (Tracer) Validate(graphql.ExecutableSchema) error {
+	return nil
+}
+
+// InterceptField adds the middleware that lets us add traces to each field of a request
+func (t Tracer) InterceptField(ctx context.Context, next graphql.Resolver) (interface{}, error) {
+	fc := graphql.GetFieldContext(ctx)
+
+	// check if this is a method or a resolver, if it's not and we aren't emitting
+	// field spans skip tracing
+	if !fc.IsMethod && !fc.IsResolver && !t.FieldSpans {
+		return next(ctx)
+	}
+
+	attrs := []attribute.KeyValue{
+		attribute.String("fieldName", fc.Field.Name),
+		attribute.String("returnType", fc.Field.Definition.Type.String()),
+	}
+
+	if fc.IsMethod {
+		for k, v := range fc.Args {
+			if strings.HasSuffix(k, "ID") || k == "id" {
+				attrs = append(attrs, attribute.String("args."+k, fmt.Sprintf("%s", v)))
+			}
+		}
+	}
+
+	ctx, span := tracer.Start(ctx, fc.Path().String(), trace.WithAttributes(attrs...))
+	defer span.End()
+
+	return next(ctx)
+}