Avoid starting all services on rebuild

Signed-off-by: Joana Hrotko <joana.hrotko@docker.com>

pkg/compose/start.go

@@ -214,13 +214,13 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 	}
 
 	var (
-		expected []string
+		expected = utils.NewSet[string]()
 		watched  = map[string]int{}
 		replaced []string
 	)
 	for _, c := range containers {
 		if isRequired(c) {
-			expected = append(expected, c.ID)
+			expected.Add(c.ID)
 		}
 		watched[c.ID] = 0
 	}
@@ -242,7 +242,7 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 					// be able to inspect in time before they're gone from the
 					// API, so just remove the watch without erroring
 					delete(watched, event.Container)
-					expected = utils.Remove(expected, event.Container)
+					expected.Remove(event.Container)
 					return nil
 				}
 				return err
@@ -253,7 +253,6 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 				Labels: inspected.Config.Labels,
 			}
 			name := getContainerNameWithoutProject(container)
-
 			service := container.Labels[api.ServiceLabel]
 			switch event.Status {
 			case "stop":
@@ -278,7 +277,7 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 				}
 
 				delete(watched, container.ID)
-				expected = utils.Remove(expected, container.ID)
+				expected.Remove(container.ID)
 			case "die":
 				restarted := watched[container.ID]
 				watched[container.ID] = restarted + 1
@@ -308,7 +307,7 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 				if !willRestart {
 					// we're done with this one
 					delete(watched, container.ID)
-					expected = utils.Remove(expected, container.ID)
+					expected.Remove(container.ID)
 				}
 			case "start":
 				count, ok := watched[container.ID]
@@ -316,7 +315,7 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 				if !ok {
 					// A new container has just been added to service by scale
 					watched[container.ID] = 0
-					expected = append(expected, container.ID)
+					expected.Add(container.ID)
 					mustAttach = true
 				}
 				if mustAttach {
@@ -333,17 +332,15 @@ func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
 					if err != nil {
 						return err
 					}
-					if utils.StringContains(expected, id) {
-						expected = append(expected, inspected.ID)
+					if expected.Has(id) {
+						expected.Add(inspected.ID)
+						expected.Add(container.ID)
 					}
 					watched[container.ID] = 1
-					if utils.Contains(expected, id) {
-						expected = append(expected, container.ID)
-					}
 				} else if ofInterest(container) {
 					watched[container.ID] = 1
 					if isRequired(container) {
-						expected = append(expected, container.ID)
+						expected.Add(container.ID)
 					}
 				}
 			}

pkg/compose/watch.go

@@ -512,9 +512,15 @@ func (s *composeService) handleWatchBatch(ctx context.Context, project *types.Pr
 				return err
 			}
 
+			services := []string{serviceName}
+			p, err := project.WithSelectedServices(services)
+			if err != nil {
+				return err
+			}
 			err = s.start(ctx, project.Name, api.StartOptions{
-				Project:  project,
-				Services: []string{serviceName},
+				Project:  p,
+				Services: services,
+				AttachTo: services,
 			}, nil)
 			if err != nil {
 				options.LogTo.Log(api.WatchLogger, fmt.Sprintf("Application failed to start after update. Error: %v", err))