fix: consistent userAgent for AWS SDK and HTTP (#291)

We should set user agent as part of our tracing package, rather than
relying on each top level entry point for a handler to set it up. We
will rely on the OTEL service name, which is consistently set as part of
each lambda config.

cmd/forwarder/main.go

@@ -114,15 +114,13 @@ func realInit() (err error) {
 
 	var s3Client forwarder.S3Client = awsS3Client
 	if strings.HasPrefix(env.DestinationURI, "https") {
-		userAgent := fmt.Sprintf("forwarder/%s", version.Version)
 		logger.V(4).Info("loading http client")
 		s3Client, err = s3http.New(&s3http.Config{
 			DestinationURI:     env.DestinationURI,
 			GetObjectAPIClient: awsS3Client,
 			HTTPClient: tracing.NewHTTPClient(&tracing.HTTPClientConfig{
 				TracerProvider: tracerProvider,
 				Logger:         &logger,
-				UserAgent:      &userAgent,
 			}),
 		})
 		if err != nil {

tracing/aws.go

@@ -3,18 +3,29 @@ package tracing
 import (
 	"context"
 	"fmt"
+	"os"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/aws/middleware"
 	"github.com/aws/aws-sdk-go-v2/config"
 	"go.opentelemetry.io/contrib/instrumentation/github.com/aws/aws-sdk-go-v2/otelaws"
 	"go.opentelemetry.io/otel/trace"
+
+	"github.com/observeinc/aws-sam-apps/version"
 )
 
 func AWSLoadDefaultConfig(ctx context.Context, tracerProvider trace.TracerProvider) (aws.Config, error) {
 	awsCfg, err := config.LoadDefaultConfig(ctx)
 	if err != nil {
 		return awsCfg, fmt.Errorf("failed to load AWS configuration: %w", err)
 	}
+
+	if serviceName := os.Getenv("OTEL_SERVICE_NAME"); serviceName != "" {
+		awsCfg.APIOptions = append(awsCfg.APIOptions,
+			middleware.AddUserAgentKeyValue(serviceName, version.Version),
+		)
+	}
+
 	otelaws.AppendMiddlewares(&awsCfg.APIOptions, otelaws.WithTracerProvider(tracerProvider))
 	return awsCfg, nil
 }

tracing/http.go

@@ -1,13 +1,17 @@
 package tracing
 
 import (
+	"fmt"
 	"net/http"
+	"os"
 	"time"
 
 	"github.com/go-logr/logr"
 	"github.com/hashicorp/go-retryablehttp"
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 	"go.opentelemetry.io/otel/trace"
+
+	"github.com/observeinc/aws-sam-apps/version"
 )
 
 // leveledLogger provides an adapter between logr.Logger and retryablehttp.LeveledLogger.
@@ -36,7 +40,6 @@ type HTTPClientConfig struct {
 	RetryWaitMax   *time.Duration // Maximumum time to wait on retry
 	RetryMax       *int           // Maximum number of retries
 	HTTPClient     *http.Client
-	UserAgent      *string
 	Logger         *logr.Logger
 	TracerProvider trace.TracerProvider
 }
@@ -72,10 +75,10 @@ func NewHTTPClient(cfg *HTTPClientConfig) *http.Client {
 	client.Logger = &leveledLogger{logger}
 
 	var transport http.RoundTripper = &retryablehttp.RoundTripper{Client: client}
-	if cfg.UserAgent != nil {
+	if serviceName := os.Getenv("OTEL_SERVICE_NAME"); serviceName != "" {
 		transport = &addUserAgent{
 			RoundTripper: transport,
-			UserAgent:    *cfg.UserAgent,
+			UserAgent:    fmt.Sprintf("%s/%s", serviceName, version.Version),
 		}
 	}
 	return &http.Client{