Add QPS and Burst configs for kubernetes client

Implemented as requested in PR723
supersedes: https://github.com/weaveworks/flagger/pull/723
fixes: https://github.com/weaveworks/flagger/issues/638

cmd/flagger/main.go

@@ -38,6 +38,8 @@ import (
 var (
 	masterURL                string
 	kubeconfig               string
+	kubeconfigQPS            int
+	kubeconfigBurst          int
 	metricsServer            string
 	controlLoopInterval      time.Duration
 	logLevel                 string
@@ -65,6 +67,8 @@ var (
 
 func init() {
 	flag.StringVar(&kubeconfig, "kubeconfig", "", "Path to a kubeconfig. Only required if out-of-cluster.")
+	flag.IntVar(&kubeconfigQPS, "kubeconfig-qps", 100, "Set QPS for kubeconfig.")
+	flag.IntVar(&kubeconfigBurst, "kubeconfig-burst", 250, "Set Burst for kubeconfig.")
 	flag.StringVar(&masterURL, "master", "", "The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.")
 	flag.StringVar(&metricsServer, "metrics-server", "http://prometheus:9090", "Prometheus URL.")
 	flag.DurationVar(&controlLoopInterval, "control-loop-interval", 10*time.Second, "Kubernetes API sync interval.")
@@ -118,6 +122,9 @@ func main() {
 		logger.Fatalf("Error building kubeconfig: %v", err)
 	}
 
+	cfg.QPS = float32(kubeconfigQPS)
+	cfg.Burst = kubeconfigBurst
+
 	kubeClient, err := kubernetes.NewForConfig(cfg)
 	if err != nil {
 		logger.Fatalf("Error building kubernetes clientset: %v", err)
@@ -137,6 +144,9 @@ func main() {
 		logger.Fatalf("Error building host kubeconfig: %v", err)
 	}
 
+	cfgHost.QPS = float32(kubeconfigQPS)
+	cfgHost.Burst = kubeconfigBurst
+
 	meshClient, err := clientset.NewForConfig(cfgHost)
 	if err != nil {
 		logger.Fatalf("Error building mesh clientset: %v", err)