fix: k8s client setup if mtls used

currently the setting up of k8s client is broken if mTLS authentication
is used between server and agent.

This fixes that.

Signed-off-by: Imran Pochi <imranpochi@microsoft.com>

Author: ipochi

cmd/server/app/options/options.go

@@ -287,29 +287,27 @@ func (o *ProxyRunOptions) Validate() error {
 	if o.EnableContentionProfiling && !o.EnableProfiling {
 		return fmt.Errorf("if --enable-contention-profiling is set, --enable-profiling must also be set")
 	}
-
-	// validate agent authentication params
-	// all 4 parameters must be empty or must have value (except KubeconfigPath that might be empty)
-	if o.AgentNamespace != "" || o.AgentServiceAccount != "" || o.AuthenticationAudience != "" || o.KubeconfigPath != "" {
+	usingServiceAccountAuth := o.AgentNamespace != "" || o.AgentServiceAccount != "" || o.AuthenticationAudience != ""
+	if usingServiceAccountAuth {
 		if o.ClusterCaCert != "" {
-			return fmt.Errorf("ClusterCaCert can not be used when service account authentication is enabled")
+			return fmt.Errorf("--cluster-ca-cert can not be used when service account authentication is enabled")
 		}
 		if o.AgentNamespace == "" {
-			return fmt.Errorf("AgentNamespace cannot be empty when agent authentication is enabled")
+			return fmt.Errorf("--agent-namespace cannot be empty when service account authentication is enabled")
 		}
 		if o.AgentServiceAccount == "" {
-			return fmt.Errorf("AgentServiceAccount cannot be empty when agent authentication is enabled")
+			return fmt.Errorf("--agent-service-account cannot be empty when service account authentication is enabled")
 		}
 		if o.AuthenticationAudience == "" {
-			return fmt.Errorf("AuthenticationAudience cannot be empty when agent authentication is enabled")
+			return fmt.Errorf("AuthenticationAudience cannot be empty when service account authentication is enabled")
 		}
-		if o.KubeconfigPath != "" {
-			if _, err := os.Stat(o.KubeconfigPath); os.IsNotExist(err) {
-				return fmt.Errorf("error checking KubeconfigPath %q, got %v", o.KubeconfigPath, err)
-			}
+	}
+	// Validate kubeconfig path if provided
+	if o.KubeconfigPath != "" {
+		if _, err := os.Stat(o.KubeconfigPath); os.IsNotExist(err) {
+			return fmt.Errorf("checking KubeconfigPath %q, got %v", o.KubeconfigPath, err)
 		}
 	}
-
 	// validate the proxy strategies
 	if len(o.ProxyStrategies) == 0 {
 		return fmt.Errorf("ProxyStrategies cannot be empty")

cmd/server/app/server.go

@@ -105,7 +105,7 @@ func (p *Proxy) Run(o *options.ProxyRunOptions, stopCh <-chan struct{}) error {
 	defer cancel()
 
 	var k8sClient *kubernetes.Clientset
-	if o.AgentNamespace != "" {
+	if util.IsRunningInKubernetes() {
 		config, err := clientcmd.BuildConfigFromFlags("", o.KubeconfigPath)
 		if err != nil {
 			return fmt.Errorf("failed to load kubernetes client config: %v", err)

pkg/util/util.go

@@ -2,6 +2,7 @@ package util
 
 import (
 	"fmt"
+	"os"
 	"strings"
 )
 
@@ -25,3 +26,11 @@ func ParseLabels(labelStr string) (map[string]string, error) {
 	}
 	return labels, nil
 }
+
+func IsRunningInKubernetes() bool {
+	if os.Getenv("KUBERNETES_SERVICE_HOST") != "" && os.Getenv("KUBERNETES_SERVICE_PORT") != "" {
+		return true
+	}
+
+	return false
+}