Fix in-cluster kubectl --namespace override

ncdc · ncdc · commit 23e32b100fb9 · 2017-05-23T15:56:48.000-04:00
Before this change, if the config was empty, ConfirmUsable() would
return an "invalid configuration" error instead of examining and
honoring the value of the --namespace flag. This change looks at the
overrides first, and returns the overridden value if it exists before
attempting to check if the config is usable. This is most applicable to
in-cluster clients, where they don't have a kubeconfig but they do have
a token and can use KUBERNETES_SERVICE_HOST/_PORT.
diff --git a/staging/src/k8s.io/client-go/tools/clientcmd/client_config.go b/staging/src/k8s.io/client-go/tools/clientcmd/client_config.go
@@ -296,6 +296,14 @@ func canIdentifyUser(config restclient.Config) bool {
 
 // Namespace implements ClientConfig
 func (config *DirectClientConfig) Namespace() (string, bool, error) {
+	if config.overrides != nil && config.overrides.Context.Namespace != "" {
+		// In the event we have an empty config but we do have a namespace override, we should return
+		// the namespace override instead of having config.ConfirmUsable() return an error. This allows
+		// things like in-cluster clients to execute `kubectl get pods --namespace=foo` and have the
+		// --namespace flag honored instead of being ignored.
+		return config.overrides.Context.Namespace, true, nil
+	}
+
 	if err := config.ConfirmUsable(); err != nil {
 		return "", false, err
 	}
@@ -309,11 +317,7 @@ func (config *DirectClientConfig) Namespace() (string, bool, error) {
 		return v1.NamespaceDefault, false, nil
 	}
 
-	overridden := false
-	if config.overrides != nil && config.overrides.Context.Namespace != "" {
-		overridden = true
-	}
-	return configContext.Namespace, overridden, nil
+	return configContext.Namespace, false, nil
 }
 
 // ConfigAccess implements ClientConfig
diff --git a/staging/src/k8s.io/client-go/tools/clientcmd/client_config_test.go b/staging/src/k8s.io/client-go/tools/clientcmd/client_config_test.go
@@ -504,3 +504,25 @@ func matchByteArg(expected, got []byte, t *testing.T) {
 		t.Errorf("Expected %v, got %v", expected, got)
 	}
 }
+
+func TestNamespaceOverride(t *testing.T) {
+	config := &DirectClientConfig{
+		overrides: &ConfigOverrides{
+			Context: clientcmdapi.Context{
+				Namespace: "foo",
+			},
+		},
+	}
+
+	ns, overridden, err := config.Namespace()
+
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !overridden {
+		t.Errorf("Expected overridden = true")
+	}
+
+	matchStringArg("foo", ns, t)
+}
