BUG/MEDIUM: fix constant reloads due to Prometheus

This fixes 2 issues:
- constant reloads (each time there is an update is the k8s cluster) to Prometheus when the Ingress Controller is started with a --namespace-whitelist option and the namespace where the controller is running is not part of the white listed namespaces.
In this situation, the prometheus backend was never created but we kept trying to create it
- do not try to create the Prometheus backend if the flag --prometheus is not set

Author: hdurand0710

pkg/controller/controller.go

@@ -149,11 +149,14 @@ func (c *HAProxyController) updateHAProxy() {
 	}
 
 	for _, namespace := range c.store.Namespaces {
-		if !namespace.Relevant {
-			continue
-		}
 		c.store.SecretsProcessed = map[string]struct{}{}
 		for _, ingResource := range namespace.Ingresses {
+			if !namespace.Relevant && !ingResource.Faked {
+				// As we watch only for white-listed namespaces, we should not worry about iterating over
+				// many ingresses in irrelevant namespaces.
+				// There should only be fake ingresses in irrelevant namespaces so loop should be whithin small amount of ingresses (Prometheus)
+				continue
+			}
 			i := ingress.New(ingResource, c.osArgs.IngressClass, c.osArgs.EmptyIngressClass, c.annotations)
 			if !i.Supported(c.store, c.annotations) {
 				logger.Debugf("ingress '%s/%s' ignored: no matching", ingResource.Namespace, ingResource.Name)

pkg/controller/handler.go

@@ -57,11 +57,13 @@ func (c *HAProxyController) initHandlers() {
 
 	defer func() { c.updateHandlers = append(c.updateHandlers, handler.Refresh{}) }()
 
-	c.beforeUpdateHandlers = []UpdateHandler{
-		handler.PrometheusEndpoint{
-			EventChan: c.eventChan,
-			PodNs:     c.podNamespace,
-		},
+	if c.osArgs.PrometheusEnabled {
+		c.beforeUpdateHandlers = []UpdateHandler{
+			handler.PrometheusEndpoint{
+				EventChan: c.eventChan,
+				PodNs:     c.podNamespace,
+			},
+		}
 	}
 	// Need to be before Refresh. If after, maps are refreshed without pprof content
 	if c.osArgs.PprofEnabled {