Merge pull request #4 from cjs/optional-endpoint

make OTel endpoint optional and use defaults if note set

cobrautil.go

@@ -18,6 +18,8 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
+	"go.opentelemetry.io/contrib/propagators/b3"
+	"go.opentelemetry.io/contrib/propagators/ot"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/jaeger"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
@@ -155,8 +157,9 @@ func RegisterOpenTelemetryFlags(flags *pflag.FlagSet, flagPrefix, serviceName st
 	prefixed := prefixJoiner(stringz.DefaultEmpty(flagPrefix, "otel"))
 
 	flags.String(prefixed("provider"), "none", `OpenTelemetry provider for tracing ("none", "jaeger, otlphttp", "otlpgrpc")`)
-	flags.String(prefixed("endpoint"), "http://collector:14268/api/traces", "collector endpoint")
+	flags.String(prefixed("endpoint"), "", "OpenTelemetry collector endpoint - the endpoint can also be set by using enviroment variables")
 	flags.String(prefixed("service-name"), serviceName, "service name for trace data")
+	flags.String(prefixed("trace-propagator"), "w3c", `OpenTelemetry trace propagation format ("b3", "w3c", "ottrace"). Add multiple propagators separated by comma.`)
 }
 
 // OpenTelemetryRunE returns a Cobra run func that configures the
@@ -173,28 +176,52 @@ func OpenTelemetryRunE(flagPrefix string, prerunLevel zerolog.Level) CobraRunFun
 
 		provider := strings.ToLower(MustGetString(cmd, prefixed("provider")))
 		serviceName := MustGetString(cmd, prefixed("service-name"))
+		endpoint := MustGetString(cmd, prefixed("endpoint"))
+		propagators := strings.Split(MustGetString(cmd, prefixed("trace-propagator")), ",")
 
+		var exporter trace.SpanExporter
+		var err error
+
+		// If endpoint is not set, the clients are configured via the OpenTelemetry environment variables or
+		// default values.
+		// See: https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlptrace#environment-variables
+		// or https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/jaeger#environment-variables
 		switch provider {
 		case "none":
 			// Nothing.
 		case "jaeger":
-			exporter, err := jaeger.New(jaeger.WithCollectorEndpoint(jaeger.WithEndpoint(MustGetString(cmd, prefixed("endpoint")))))
+			var opts []jaeger.CollectorEndpointOption
+			if endpoint != "" {
+				opts = append(opts, jaeger.WithEndpoint(endpoint))
+			}
+
+			exporter, err = jaeger.New(jaeger.WithCollectorEndpoint(opts...))
 			if err != nil {
 				return err
 			}
-			return initOtelTracer(exporter, serviceName)
+			return initOtelTracer(exporter, serviceName, propagators)
 		case "otlphttp":
-			exporter, err := otlptrace.New(context.Background(), otlptracehttp.NewClient())
+			var opts []otlptracehttp.Option
+			if endpoint != "" {
+				opts = append(opts, otlptracehttp.WithEndpoint(endpoint))
+			}
+
+			exporter, err = otlptrace.New(context.Background(), otlptracehttp.NewClient(opts...))
 			if err != nil {
 				return err
 			}
-			return initOtelTracer(exporter, serviceName)
+			return initOtelTracer(exporter, serviceName, propagators)
 		case "otlpgrpc":
-			exporter, err := otlptrace.New(context.Background(), otlptracegrpc.NewClient())
+			var opts []otlptracegrpc.Option
+			if endpoint != "" {
+				opts = append(opts, otlptracegrpc.WithEndpoint(endpoint))
+			}
+
+			exporter, err = otlptrace.New(context.Background(), otlptracegrpc.NewClient(opts...))
 			if err != nil {
 				return err
 			}
-			return initOtelTracer(exporter, serviceName)
+			return initOtelTracer(exporter, serviceName, propagators)
 		default:
 			return fmt.Errorf("unknown tracing provider: %s", provider)
 		}
@@ -204,7 +231,7 @@ func OpenTelemetryRunE(flagPrefix string, prerunLevel zerolog.Level) CobraRunFun
 	}
 }
 
-func initOtelTracer(exporter trace.SpanExporter, serviceName string) error {
+func initOtelTracer(exporter trace.SpanExporter, serviceName string, propagators []string) error {
 	res, _ := resource.Merge(
 		resource.Default(),
 		resource.NewSchemaless(semconv.ServiceNameKey.String(serviceName)),
@@ -217,20 +244,33 @@ func initOtelTracer(exporter trace.SpanExporter, serviceName string) error {
 	)
 
 	otel.SetTracerProvider(tp)
-
-	// Configure the global tracer to use the W3C method for propagating contexts
-	// across services.
-	//
-	// For low-level details see:
-	// https://www.w3.org/TR/trace-context/
-	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(
-		propagation.Baggage{},      // W3C baggage support
-		propagation.TraceContext{}, // W3C for compatibility with other tracing system
-	))
+	setTracePropagators(propagators)
 
 	return nil
 }
 
+// setTextMapPropagator sets the OpenTelemetry trace propagation format.
+// Currently it supports b3, ot-trace and w3c.
+func setTracePropagators(propagators []string) {
+	var tmPropagators []propagation.TextMapPropagator
+
+	for _, p := range propagators {
+		switch p {
+		case "b3":
+			tmPropagators = append(tmPropagators, b3.New())
+		case "ottrace":
+			tmPropagators = append(tmPropagators, ot.OT{})
+		case "w3c":
+			fallthrough
+		default:
+			tmPropagators = append(tmPropagators, propagation.Baggage{})      // W3C baggage support
+			tmPropagators = append(tmPropagators, propagation.TraceContext{}) // W3C for compatibility with other tracing system
+		}
+	}
+
+	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(tmPropagators...))
+}
+
 // RegisterGrpcServerFlags adds the following flags for use with
 // GrpcServerFromFlags:
 // - "$PREFIX-addr"

go.mod

@@ -9,6 +9,8 @@ require (
 	github.com/spf13/cobra v1.1.3
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.1
+	go.opentelemetry.io/contrib/propagators/b3 v1.3.0
+	go.opentelemetry.io/contrib/propagators/ot v1.3.0
 	go.opentelemetry.io/otel v1.3.0
 	go.opentelemetry.io/otel/exporters/jaeger v1.3.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.3.0

go.sum

@@ -244,6 +244,10 @@ github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1
 go.etcd.io/bbolt v1.3.2/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 go.opencensus.io v0.21.0/go.mod h1:mSImk1erAIZhrmZN+AvHh14ztQfjbGwt4TtuofqLduU=
 go.opencensus.io v0.22.0/go.mod h1:+kGneAE2xo2IficOXnaByMWTGM9T73dGwxeWcUqIpI8=
+go.opentelemetry.io/contrib/propagators/b3 v1.3.0 h1:f+JfMSDNm2u+fekYYjyoixk+DWDTDAGD3SC50y61koE=
+go.opentelemetry.io/contrib/propagators/b3 v1.3.0/go.mod h1:qzi0km8qO3l2jxB5aDg4Q9xyqV4HKnCWZYpVYDTUIT0=
+go.opentelemetry.io/contrib/propagators/ot v1.3.0 h1:hqFpnicJXKy8l8PfwFWhRSt/TgOHCpugKiXsPP1zJUc=
+go.opentelemetry.io/contrib/propagators/ot v1.3.0/go.mod h1:Gpwe4R8j9Zbw7aaADYSQRE1U0o41j0TwnHxuhwRLklk=
 go.opentelemetry.io/otel v1.3.0 h1:APxLf0eiBwLl+SOXiJJCVYzA1OOJNyAoV8C5RNRyy7Y=
 go.opentelemetry.io/otel v1.3.0/go.mod h1:PWIKzi6JCp7sM0k9yZ43VX+T345uNbAkDKwHVjb2PTs=
 go.opentelemetry.io/otel/exporters/jaeger v1.3.0 h1:HfydzioALdtcB26H5WHc4K47iTETJCdloL7VN579/L0=