add memory warning

Author: lionello

src/pkg/cli/composeStart.go

@@ -230,6 +230,7 @@ func ComposeStart(ctx context.Context, client defangv1connect.FabricControllerCl
 
 		ports, err := convertPorts(svccfg.Ports)
 		if err != nil {
+			// TODO: move this validation up so we don't upload the build context if it's invalid
 			return nil, &ComposeError{err}
 		}
 		// Show a warning when we have ingress ports but no explicit healthcheck
@@ -243,7 +244,7 @@ func ComposeStart(ctx context.Context, client defangv1connect.FabricControllerCl
 		var deploy *pb.Deploy
 		if svccfg.Deploy != nil {
 			deploy = &pb.Deploy{}
-			deploy.Replicas = 1 // default to one replica per service
+			deploy.Replicas = 1 // default to one replica per service; allow the user to override this to 0
 			if svccfg.Deploy.Replicas != nil {
 				deploy.Replicas = uint32(*svccfg.Deploy.Replicas)
 			}
@@ -253,9 +254,9 @@ func ComposeStart(ctx context.Context, client defangv1connect.FabricControllerCl
 				reservations = svccfg.Deploy.Resources.Limits
 			}
 			if reservations != nil {
-				// TODO: move this validation up so we don't upload the build context if it's invalid
 				cpus, err := strconv.ParseFloat(reservations.NanoCPUs, 32)
 				if err != nil {
+					// TODO: move this validation up so we don't upload the build context if it's invalid
 					return nil, &ComposeError{fmt.Errorf("invalid reservations cpus: %v", err)}
 				}
 				var devices []*pb.Device
@@ -276,6 +277,10 @@ func ComposeStart(ctx context.Context, client defangv1connect.FabricControllerCl
 			}
 		}
 
+		if deploy == nil || deploy.Resources == nil || deploy.Resources.Reservations == nil || deploy.Resources.Reservations.Memory == 0 {
+			logrus.Warn("missing memory reservation; specify deploy.resources.reservations.memory to avoid out-of-memory errors")
+		}
+
 		// Upload the build context, if any; TODO: parallelize
 		var build *pb.Build
 		if svccfg.Build != nil {

src/tests/docker-compose.yml

@@ -7,6 +7,14 @@ services:
         DNS: "${COMPOSE_PROJECT_NAME}-dfnx.prod1.defang.dev"
     env_file:
       - fileName.env
+    # deploy:
+    #   resources:
+    #     limits:
+    #       cpus: '0.50'
+    #       memory: 512M
+    #     reservations:
+    #       cpus: '0.25'
+    #       memory: 256M
     ports:
       - target: 80
         mode: ingress