Add a new option to enable otel roundtrip tracing

Currently, there is no option to enable otel tracing for ocm.
Adding EnableOtel option to allow users to config the controller
to support otel tracing by wrapping http.RoundTripper with one that
starts a span, injects the span context into the outbound request headers,
and enriches it with metrics.

Signed-off-by: Vu Dinh <[email protected]>

Author: dinhxuanvu

pkg/common/options/options.go

@@ -8,40 +8,48 @@ import (
 	"github.com/spf13/pflag"
 	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/utils/clock"
+
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 )
 
 type Options struct {
-	CmdConfig *controllercmd.ControllerCommandConfig
-	Burst     int
-	QPS       float32
+	CmdConfig  *controllercmd.ControllerCommandConfig
+	Burst      int
+	QPS        float32
+	EnableOtel bool
 }
 
 // NewOptions returns the flags with default value set
 func NewOptions() *Options {
 	opts := &Options{
-		QPS:   50,
-		Burst: 100,
+		QPS:        50,
+		Burst:      100,
+		EnableOtel: false,
 	}
 	return opts
 }
 
 func (o *Options) NewControllerCommandConfig(
 	componentName string, version version.Info, startFunc controllercmd.StartFunc, clock clock.Clock) *controllercmd.ControllerCommandConfig {
-	o.CmdConfig = controllercmd.NewControllerCommandConfig(componentName, version, o.startWithQPS(startFunc), clock)
+	o.CmdConfig = controllercmd.NewControllerCommandConfig(componentName, version, o.startWithOptions(startFunc), clock)
 	return o.CmdConfig
 }
 
-func (o *Options) startWithQPS(startFunc controllercmd.StartFunc) controllercmd.StartFunc {
+func (o *Options) startWithOptions(startFunc controllercmd.StartFunc) controllercmd.StartFunc {
 	return func(ctx context.Context, controllerContext *controllercmd.ControllerContext) error {
 		controllerContext.KubeConfig.QPS = o.QPS
 		controllerContext.KubeConfig.Burst = o.Burst
+		if o.EnableOtel {
+			controllerContext.KubeConfig.Transport = otelhttp.NewTransport(controllerContext.KubeConfig.Transport)
+		}
 		return startFunc(ctx, controllerContext)
 	}
 }
 
 func (o *Options) AddFlags(flags *pflag.FlagSet) {
 	flags.Float32Var(&o.QPS, "kube-api-qps", o.QPS, "QPS to use while talking with apiserver on spoke cluster.")
 	flags.IntVar(&o.Burst, "kube-api-burst", o.Burst, "Burst to use while talking with apiserver on spoke cluster.")
+	flags.BoolVar(&o.EnableOtel, "enable-otel-roundtrip", o.EnableOtel, "enable OpenTelemetry roundtrip.")
 	if o.CmdConfig != nil {
 		flags.BoolVar(&o.CmdConfig.DisableLeaderElection, "disable-leader-election", false, "Disable leader election.")
 		flags.DurationVar(&o.CmdConfig.LeaseDuration.Duration, "leader-election-lease-duration", 137*time.Second, ""+