fix: restore kube health check

With the recent changes to the protocol and to routing there is no real need
for the controller to ping the runner. This ping was causing the ISTIO RBAC
issues that resulted in us disabling the health check.

fixes: #2710

backend/controller/controller.go

@@ -548,7 +548,7 @@ func (s *Service) ReplaceDeploy(ctx context.Context, c *connect.Request[ftlv1.Re
 }
 
 func (s *Service) RegisterRunner(ctx context.Context, stream *connect.ClientStream[ftlv1.RegisterRunnerRequest]) (*connect.Response[ftlv1.RegisterRunnerResponse], error) {
-	initialised := false
+
 	deferredDeregistration := false
 
 	logger := log.FromContext(ctx)
@@ -569,14 +569,6 @@ func (s *Service) RegisterRunner(ctx context.Context, stream *connect.ClientStre
 		runnerStr := fmt.Sprintf("%s (%s)", endpoint, runnerKey)
 		logger.Tracef("Heartbeat received from runner %s", runnerStr)
 
-		if !initialised {
-			err = s.pingRunner(ctx, endpoint)
-			if err != nil {
-				return nil, fmt.Errorf("runner callback failed: %w", err)
-			}
-			initialised = true
-		}
-
 		deploymentKey, err := model.ParseDeploymentKey(msg.Deployment)
 		if err != nil {
 			return nil, connect.NewError(connect.CodeInvalidArgument, err)
@@ -613,19 +605,6 @@ func (s *Service) RegisterRunner(ctx context.Context, stream *connect.ClientStre
 	return connect.NewResponse(&ftlv1.RegisterRunnerResponse{}), nil
 }
 
-// Check if we can contact the runner.
-func (s *Service) pingRunner(ctx context.Context, endpoint *url.URL) error {
-	client := rpc.Dial(ftlv1connect.NewVerbServiceClient, endpoint.String(), log.Error)
-	retry := backoff.Backoff{}
-	heartbeatCtx, cancel := context.WithTimeout(ctx, s.config.RunnerTimeout)
-	defer cancel()
-	err := rpc.Wait(heartbeatCtx, retry, client)
-	if err != nil {
-		return connect.NewError(connect.CodeUnavailable, fmt.Errorf("failed to connect to runner: %w", err))
-	}
-	return nil
-}
-
 func (s *Service) GetDeployment(ctx context.Context, req *connect.Request[ftlv1.GetDeploymentRequest]) (*connect.Response[ftlv1.GetDeploymentResponse], error) {
 	deployment, err := s.getDeployment(ctx, req.Msg.DeploymentKey)
 	if err != nil {

backend/runner/runner.go

@@ -132,6 +132,7 @@ func Start(ctx context.Context, config Config) error {
 	return rpc.Serve(ctx, config.Bind,
 		rpc.GRPC(ftlv1connect.NewVerbServiceHandler, svc),
 		rpc.HTTP("/", svc),
+		rpc.HealthCheck(svc.healthCheck),
 	)
 }