pkg/start: Drop the internal EnableMetrics

We've had it since 2b81f47 (cvo: Release our leader lease when we
are gracefully terminated, 2019-01-16, #87), but it's redundant
vs. "ListenAddr is not an empty string".

I'm also switching to:

  o.ListenAddr != ""

instead of:

  len(o.ListenAddr) > 0

because it seems slightly easier to understand, but obviously either
will work.

Cherry-picked from 07e5809 (#349), around conflicts due to the lack
of TLS metrics in 4.5.

pkg/start/start.go

@@ -67,7 +67,6 @@ type Options struct {
 	Name            string
 	Namespace       string
 	PayloadOverride string
-	EnableMetrics   bool
 	ResyncInterval  time.Duration
 }
 
@@ -91,7 +90,6 @@ func NewOptions() *Options {
 		Name:            defaultEnv("CVO_NAME", defaultComponentName),
 		PayloadOverride: os.Getenv("PAYLOAD_OVERRIDE"),
 		ResyncInterval:  minResyncPeriod,
-		EnableMetrics:   true,
 		Exclude:         os.Getenv("EXCLUDE_MANIFESTS"),
 	}
 }
@@ -155,7 +153,7 @@ func (o *Options) Run() error {
 
 func (o *Options) run(ctx context.Context, controllerCtx *Context, lock *resourcelock.ConfigMapLock) {
 	// listen on metrics
-	if len(o.ListenAddr) > 0 {
+	if o.ListenAddr != "" {
 		mux := http.NewServeMux()
 		mux.Handle("/metrics", promhttp.Handler())
 		go func() {
@@ -345,7 +343,7 @@ func (o *Options) NewControllerContext(cb *ClientBuilder) *Context {
 			sharedInformers.Config().V1().Proxies(),
 			cb.ClientOrDie(o.Namespace),
 			cb.KubeClientOrDie(o.Namespace, useProtobuf),
-			o.EnableMetrics,
+			o.ListenAddr != "",
 			o.Exclude,
 		),
 	}

pkg/start/start_integration_test.go

@@ -238,7 +238,6 @@ func TestIntegrationCVO_initializeAndUpgrade(t *testing.T) {
 	options.NodeName = "test-node"
 	options.ReleaseImage = payloadImage1
 	options.PayloadOverride = filepath.Join(dir, "ignored")
-	options.EnableMetrics = false
 	controllers := options.NewControllerContext(cb)
 
 	worker := cvo.NewSyncWorker(retriever, cvo.NewResourceBuilder(cfg, cfg, nil), 5*time.Second, wait.Backoff{Steps: 3}, "")
@@ -390,7 +389,6 @@ func TestIntegrationCVO_initializeAndHandleError(t *testing.T) {
 	options.NodeName = "test-node"
 	options.ReleaseImage = payloadImage1
 	options.PayloadOverride = filepath.Join(dir, "ignored")
-	options.EnableMetrics = false
 	options.ResyncInterval = 3 * time.Second
 	controllers := options.NewControllerContext(cb)
 
@@ -497,7 +495,6 @@ func TestIntegrationCVO_gracefulStepDown(t *testing.T) {
 	options.Name = ns
 	options.ListenAddr = ""
 	options.NodeName = "test-node"
-	options.EnableMetrics = false
 	controllers := options.NewControllerContext(cb)
 
 	worker := cvo.NewSyncWorker(&mapPayloadRetriever{}, cvo.NewResourceBuilder(cfg, cfg, nil), 5*time.Second, wait.Backoff{Steps: 3}, "")
@@ -667,7 +664,6 @@ metadata:
 	options.NodeName = "test-node"
 	options.ReleaseImage = payloadImage1
 	options.PayloadOverride = payloadDir
-	options.EnableMetrics = false
 	controllers := options.NewControllerContext(cb)
 	if err := controllers.CVO.InitializeFromPayload(cb.RestConfig(defaultQPS), cb.RestConfig(highQPS)); err != nil {
 		t.Fatal(err)