Create new instance of collectors for every request

This restores previous behaviour where every request would create
collectors and register them

main.go

@@ -22,7 +22,11 @@ import (
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 )
 
-var metricsNamespace = "kube_summary"
+var (
+	flagKubeConfigPath = flag.String("kubeconfig", "", "Path of a kubeconfig file, if not provided the app will try $KUBECONFIG, $HOME/.kube/config or in cluster config")
+	flagListenAddress  = flag.String("listen-address", ":9779", "Listen address")
+	metricsNamespace   = "kube_summary"
+)
 
 type Collectors struct {
 	containerLogsInodesFree           *prometheus.GaugeVec
@@ -298,18 +302,19 @@ func collectSummaryMetrics(summary *stats.Summary, collectors *Collectors) {
 }
 
 // nodeHandler returns metrics for the /stats/summary API of the given node
-func nodeHandler(w http.ResponseWriter, r *http.Request, kubeClient *kubernetes.Clientset, collectors *Collectors) {
+func nodeHandler(w http.ResponseWriter, r *http.Request, kubeClient *kubernetes.Clientset) {
 	node := mux.Vars(r)["node"]
 
-	ctx, cancel := getTimeoutContext(r)
+	ctx, cancel := timeoutContext(r)
 	defer cancel()
 
-	summary, err := getNodeSummary(ctx, kubeClient, node)
+	summary, err := nodeSummary(ctx, kubeClient, node)
 	if err != nil {
 		http.Error(w, fmt.Sprintf("Error querying /stats/summary for %s: %v", node, err), http.StatusInternalServerError)
 		return
 	}
 
+	collectors := newCollectors()
 	registry := prometheus.NewRegistry()
 	collectors.register(registry)
 	collectSummaryMetrics(summary, collectors)
@@ -319,8 +324,8 @@ func nodeHandler(w http.ResponseWriter, r *http.Request, kubeClient *kubernetes.
 }
 
 // allNodesHandler returns metrics for all nodes in the cluster
-func allNodesHandler(w http.ResponseWriter, r *http.Request, kubeClient *kubernetes.Clientset, collectors *Collectors) {
-	ctx, cancel := getTimeoutContext(r)
+func allNodesHandler(w http.ResponseWriter, r *http.Request, kubeClient *kubernetes.Clientset) {
+	ctx, cancel := timeoutContext(r)
 	defer cancel()
 
 	nodes, err := kubeClient.CoreV1().Nodes().List(ctx, metav1.ListOptions{})
@@ -329,11 +334,12 @@ func allNodesHandler(w http.ResponseWriter, r *http.Request, kubeClient *kuberne
 		return
 	}
 
+	collectors := newCollectors()
 	registry := prometheus.NewRegistry()
 	collectors.register(registry)
 
 	for _, node := range nodes.Items {
-		summary, err := getNodeSummary(ctx, kubeClient, node.Name)
+		summary, err := nodeSummary(ctx, kubeClient, node.Name)
 		if err != nil {
 			http.Error(w, fmt.Sprintf("Error querying /stats/summary for %s: %v", node.Name, err), http.StatusInternalServerError)
 			return
@@ -345,8 +351,8 @@ func allNodesHandler(w http.ResponseWriter, r *http.Request, kubeClient *kuberne
 	h.ServeHTTP(w, r)
 }
 
-// getNodeSummary retrieves the summary for a single node
-func getNodeSummary(ctx context.Context, kubeClient *kubernetes.Clientset, nodeName string) (*stats.Summary, error) {
+// nodeSummary retrieves the summary for a single node
+func nodeSummary(ctx context.Context, kubeClient *kubernetes.Clientset, nodeName string) (*stats.Summary, error) {
 	req := kubeClient.CoreV1().RESTClient().Get().Resource("nodes").Name(nodeName).SubResource("proxy").Suffix("stats/summary")
 	resp, err := req.DoRaw(ctx)
 	if err != nil {
@@ -361,8 +367,8 @@ func getNodeSummary(ctx context.Context, kubeClient *kubernetes.Clientset, nodeN
 	return summary, nil
 }
 
-// getTimeoutContext returns a context with timeout based on the X-Prometheus-Scrape-Timeout-Seconds header
-func getTimeoutContext(r *http.Request) (context.Context, context.CancelFunc) {
+// timeoutContext returns a context with timeout based on the X-Prometheus-Scrape-Timeout-Seconds header
+func timeoutContext(r *http.Request) (context.Context, context.CancelFunc) {
 	if v := r.Header.Get("X-Prometheus-Scrape-Timeout-Seconds"); v != "" {
 		timeoutSeconds, err := strconv.ParseFloat(v, 64)
 		if err == nil {
@@ -399,11 +405,6 @@ func newKubeClient(path string) (*kubernetes.Clientset, error) {
 	return kubernetes.NewForConfig(config)
 }
 
-var (
-	flagListenAddress  = flag.String("listen-address", ":9779", "Listen address")
-	flagKubeConfigPath = flag.String("kubeconfig", "", "Path of a kubeconfig file, if not provided the app will try $KUBECONFIG, $HOME/.kube/config or in cluster config")
-)
-
 func main() {
 	flag.Parse()
 
@@ -413,14 +414,12 @@ func main() {
 		os.Exit(1)
 	}
 
-	collectors := newCollectors()
-
 	r := mux.NewRouter()
 	r.HandleFunc("/nodes", func(w http.ResponseWriter, r *http.Request) {
-		allNodesHandler(w, r, kubeClient, collectors)
+		allNodesHandler(w, r, kubeClient)
 	})
 	r.HandleFunc("/node/{node}", func(w http.ResponseWriter, r *http.Request) {
-		nodeHandler(w, r, kubeClient, collectors)
+		nodeHandler(w, r, kubeClient)
 	})
 	r.Handle("/metrics", promhttp.Handler())
 	r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {