feat(exporter): load kubeconfig from a new argument, or env variable

cmd/x509-certificate-exporter/main.go

@@ -40,6 +40,8 @@ func main() {
 
 	kubeEnabled := getopt.BoolLong("watch-kube-secrets", 0, "scrape kubernetes secrets and monitor them")
 
+	kubeConfig := getopt.StringLong("kubeconfig", 0, "", "Path to the kubeconfig file to use for requests. Takes precedence over the KUBECONFIG environment variable, and default path (~/.kube/config).", "path")
+
 	kubeSecretTypes := stringArrayFlag{}
 	getopt.FlagLong(&kubeSecretTypes, "secret-type", 's', "one or more kubernetes secret type & key to watch (e.g. \"kubernetes.io/tls:tls.crt\"")
 
@@ -105,18 +107,21 @@ func main() {
 	}
 
 	if *kubeEnabled {
-		err := exporter.ConnectToKubernetesCluster("")
-		if err != nil {
-			log.Warn(err)
+		defaultKubeConfig := path.Join(os.Getenv("HOME"), ".kube", "config")
+		kubeConfigEnv := os.Getenv("KUBECONFIG")
 
-			configpath := os.Getenv("KUBECONFIG")
-			if len(configpath) == 0 {
-				configpath = path.Join(os.Getenv("HOME"), ".kube/config")
-			}
-			err = exporter.ConnectToKubernetesCluster(configpath)
-			if err != nil {
-				log.Fatal(err)
-			}
+		configpath := ""
+		if len(*kubeConfig) > 0 {
+			configpath = *kubeConfig
+		} else if len(kubeConfigEnv) > 0 {
+			configpath = kubeConfigEnv
+		} else if _, err := os.Stat(defaultKubeConfig); err == nil {
+			configpath = defaultKubeConfig
+		}
+
+		err := exporter.ConnectToKubernetesCluster(configpath)
+		if err != nil {
+			log.Fatal(err)
 		}
 	}
 

internal/kubernetes.go

@@ -251,10 +251,10 @@ func parseKubeConfig(kubeconfigPath string) (*rest.Config, error) {
 	var err error
 
 	if len(kubeconfigPath) > 0 {
-		log.Infof("reading config from %s", kubeconfigPath)
+		log.Infof("using kubeconfig file: %s", kubeconfigPath)
 		config, err = clientcmd.BuildConfigFromFlags("", kubeconfigPath)
 	} else {
-		log.Info("fetching configuration from within the cluster")
+		log.Info("no kubeconfig file provided, attempting to load in-cluster configuration")
 		config, err = rest.InClusterConfig()
 	}