fix: error out if missing "deploy.labels"

See toolshed/organising#643

pkg/lint/recipe.go

@@ -137,6 +137,13 @@ var LintRules = map[string][]LintRule{
 			HowToResolve: "name a servce 'app'",
 			Function:     LintAppService,
 		},
+		{
+			Ref:          "R015",
+			Level:        "error",
+			Description:  "deploy labels stanza present",
+			HowToResolve: "include \"deploy: labels: ...\" stanza",
+			Function:     LintDeployLabelsPresent,
+		},
 		{
 			Ref:           "R010",
 			Level:         "error",
@@ -269,6 +276,21 @@ func LintTraefikEnabled(recipe recipe.Recipe) (bool, error) {
 	return false, nil
 }
 
+func LintDeployLabelsPresent(recipe recipe.Recipe) (bool, error) {
+	config, err := recipe.GetComposeConfig(nil)
+	if err != nil {
+		return false, err
+	}
+
+	for _, service := range config.Services {
+		if service.Name == "app" && service.Deploy.Labels != nil {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
 func LintHealthchecks(recipe recipe.Recipe) (bool, error) {
 	config, err := recipe.GetComposeConfig(nil)
 	if err != nil {