Set Temporal-Namespace header on every namespace-specific gRPC request

internal/grpc_dialer.go

@@ -76,6 +76,9 @@ const (
 
 	// defaultKeepAliveTimeout is the keep alive timeout if one is not specified.
 	defaultKeepAliveTimeout = 15 * time.Second
+
+	// temporalNamespaceHeaderKey is the header key that should contain the target namespace of the request.
+	temporalNamespaceHeaderKey = "temporal-namespace"
 )
 
 func dial(params dialParameters) (*grpc.ClientConn, error) {
@@ -176,9 +179,23 @@ func requiredInterceptors(
 			interceptors = append(interceptors, interceptor)
 		}
 	}
+	// Add namespace provider interceptor
+	interceptors = append(interceptors, namespaceProviderInterceptor())
 	return interceptors
 }
 
+func namespaceProviderInterceptor() grpc.UnaryClientInterceptor {
+	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+		if nsReq, ok := req.(interface{ GetNamespace() string }); ok {
+			// Only add namespace if it doesn't already exist
+			if md, _ := metadata.FromOutgoingContext(ctx); len(md.Get(temporalNamespaceHeaderKey)) == 0 {
+				ctx = metadata.AppendToOutgoingContext(ctx, temporalNamespaceHeaderKey, nsReq.GetNamespace())
+			}
+		}
+		return invoker(ctx, method, req, reply, cc, opts...)
+	}
+}
+
 func trafficControllerInterceptor(controller TrafficController) grpc.UnaryClientInterceptor {
 	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
 		err := controller.CheckCallAllowed(ctx, method, req, reply)

internal/grpc_dialer_test.go

@@ -485,6 +485,33 @@ func TestCredentialsAPIKey(t *testing.T) {
 	)
 }
 
+func TestNamespaceInterceptor(t *testing.T) {
+	srv, err := startTestGRPCServer()
+	require.NoError(t, err)
+	defer srv.Stop()
+
+	// Fixed string
+	client, err := DialClient(context.Background(), ClientOptions{
+		Namespace: "test-namespace",
+		HostPort:  srv.addr,
+	})
+	require.NoError(t, err)
+	defer client.Close()
+	// Verify namespace header is set in the context even though getSystemInfo doesn't have it on the request
+	require.Equal(
+		t,
+		[]string{"test-namespace"},
+		metadata.ValueFromIncomingContext(srv.getSystemInfoRequestContext, temporalNamespaceHeaderKey),
+	)
+	// Verify namespace header is set on a request that does have namespace on the request
+	require.NoError(t, client.SignalWorkflow(context.Background(), "workflowid", "runid", "signalname", nil))
+	require.Equal(
+		t,
+		[]string{"test-namespace"},
+		metadata.ValueFromIncomingContext(srv.lastSignalWorkflowExecutionContext, temporalNamespaceHeaderKey),
+	)
+}
+
 func TestCredentialsMTLS(t *testing.T) {
 	// Just confirming option is set, not full end-to-end mTLS test
 
@@ -520,6 +547,7 @@ type testGRPCServer struct {
 	getSystemInfoRequestContext          context.Context
 	getSystemInfoResponse                workflowservice.GetSystemInfoResponse
 	getSystemInfoResponseError           error
+	lastSignalWorkflowExecutionContext   context.Context
 	signalWorkflowExecutionResponse      workflowservice.SignalWorkflowExecutionResponse
 	signalWorkflowExecutionResponseError error
 }
@@ -579,10 +607,11 @@ func (t *testGRPCServer) GetSystemInfo(
 }
 
 func (t *testGRPCServer) SignalWorkflowExecution(
-	context.Context,
-	*workflowservice.SignalWorkflowExecutionRequest,
+	ctx context.Context,
+	_ *workflowservice.SignalWorkflowExecutionRequest,
 ) (*workflowservice.SignalWorkflowExecutionResponse, error) {
 	atomic.AddInt32(&t.sigWfCount, 1)
+	t.lastSignalWorkflowExecutionContext = ctx
 	return &t.signalWorkflowExecutionResponse, t.signalWorkflowExecutionResponseError
 }
 

internal/internal_workflow_client.go

@@ -39,6 +39,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/durationpb"
 
@@ -1167,6 +1168,8 @@ func (wc *WorkflowClient) loadCapabilities(ctx context.Context, getSystemInfoTim
 	}
 	ctx, cancel := context.WithTimeout(ctx, getSystemInfoTimeout)
 	defer cancel()
+	// Manually append the namespace to the header since the request does not have it.
+	ctx = metadata.AppendToOutgoingContext(ctx, temporalNamespaceHeaderKey, wc.namespace)
 	resp, err := wc.workflowService.GetSystemInfo(ctx, &workflowservice.GetSystemInfoRequest{})
 	// We ignore unimplemented
 	if _, isUnimplemented := err.(*serviceerror.Unimplemented); err != nil && !isUnimplemented {