fix(auth): complete Task 13 deployment review

tools/tht/internal/backup/create.go

@@ -394,7 +394,8 @@ type renderedCompose struct {
 		Name string `json:"name"`
 	} `json:"volumes"`
 	Services map[string]struct {
-		Image string `json:"image"`
+		Image         string `json:"image"`
+		ContainerName string `json:"container_name"`
 	} `json:"services"`
 }
 
@@ -474,18 +475,13 @@ func imageIdentities(ctx context.Context, installation config.Installation, runn
 		if err != nil {
 			return nil, err
 		}
-		matching := make([]composeImageIdentity, 0, len(inspected))
-		for _, item := range inspected {
-			if item.Service == "" || item.Service == name {
-				matching = append(matching, item)
-			}
+		expectedContainer := rendered.Services[name].ContainerName
+		if expectedContainer == "" {
+			expectedContainer = installation.ProjectName() + "-" + name + "-1"
 		}
-		if len(matching) > 1 {
-			return nil, errors.New("Docker Compose returned invalid image identities")
-		}
-		id := ""
-		if len(matching) == 1 {
-			id = matching[0].ID
+		id, err := selectComposeImageIdentity(name, expectedContainer, inspected)
+		if err != nil {
+			return nil, err
 		}
 		images = append(images, ImageIdentity{Service: name, Reference: rendered.Services[name].Image, ID: id})
 	}
@@ -500,7 +496,7 @@ type composeImageIdentity struct {
 
 func decodeComposeImageIdentities(value string) ([]composeImageIdentity, error) {
 	trimmed := strings.TrimSpace(value)
-	if trimmed == "" {
+	if trimmed == "" || trimmed == "null" {
 		return nil, nil
 	}
 	var identities []composeImageIdentity
@@ -530,6 +526,22 @@ func decodeComposeImageIdentities(value string) ([]composeImageIdentity, error)
 	return identities, nil
 }
 
+func selectComposeImageIdentity(service string, expectedContainer string, identities []composeImageIdentity) (string, error) {
+	if len(identities) == 0 {
+		return "", nil
+	}
+	matching := make([]composeImageIdentity, 0, len(identities))
+	for _, item := range identities {
+		if item.Service == service || item.Service == "" && item.ContainerName == expectedContainer {
+			matching = append(matching, item)
+		}
+	}
+	if len(matching) != 1 {
+		return "", errors.New("Docker Compose returned invalid image identities")
+	}
+	return matching[0].ID, nil
+}
+
 func installationRunning(ctx context.Context, installation config.Installation, runner archiveRunner) (bool, error) {
 	result, err := runner.Run(ctx, installation.ComposeArgs("ps", "--all", "--format", "json"), nil)
 	if err != nil {