chore(aft): Custom GitHub actions config

Currently, `aft generate workflows` checks for the presence of a `workflow.yaml` file next to a `pubspec.yaml` to know if we should generate a GitHub action workflow or copy over the custom one. This leads to drift, though, since dependabot does not search these directories by default.

We could update Dependabot to search these directories, but instead we add a setting to the aft config to say that the workflow which exists is custom and should not be overridden so that the information is not copied in two places.

packages/aft/lib/src/commands/generate/generate_workflows_command.dart

@@ -119,10 +119,9 @@ ${dependentPackages.map((dep) => '      - dependency-name: "${dep.name}"').join(
     required String repoRelativePath,
     required List<PackageInfo> dependentPackages,
   }) async {
-    // Packages without a `lib/` folder generally contain only native code,
-    // e.g. `amplify_auth_cognito_android`. These packages are tested via their
-    // parent package, e.g. `amplify_flutter`, and do not require a workflow
-    // of their own.
+    // Packages without a `lib/` folder generally contain only native code.
+    // These packages are tested via their parent package and do not require
+    // a workflow of their own.
     final libDir = Directory(p.join(package.path, 'lib'));
     if (!libDir.existsSync()) {
       return;
@@ -134,9 +133,13 @@ ${dependentPackages.map((dep) => '      - dependency-name: "${dep.name}"').join(
       '${package.name}.yaml',
     );
     final workflowFile = File(workflowFilepath);
-    final customWorkflow = File(p.join(package.path, 'workflow.yaml'));
-    if (customWorkflow.existsSync()) {
-      customWorkflow.copySync(workflowFilepath);
+    if (package.pubspecInfo.config.aft?.github?.custom ?? false) {
+      if (!workflowFile.existsSync()) {
+        throw Exception(
+          'Package "${package.name}" sets `custom: true` but no workflow '
+          'file was found at: $workflowFilepath',
+        );
+      }
       return;
     }
     final isDartPackage = package.flavor == PackageFlavor.dart;

packages/aft/lib/src/config/config.dart

@@ -396,6 +396,12 @@ class PubspecInfo with AWSSerializable<Map<String, Object?>>, AWSDebuggable {
   /// The package's pubspec as a YAML map.
   final YamlMap pubspecMap;
 
+  /// Package-specific configuration.
+  @JsonKey(includeToJson: false, includeFromJson: false)
+  late final RawPubspecConfig config = RawPubspecConfig.fromJson(
+    pubspecMap.cast(),
+  );
+
   /// The pubspec as a YAML editor, used to alter dependencies or other info.
   @JsonKey(includeFromJson: false, includeToJson: false)
   late final YamlEditor pubspecYamlEditor = YamlEditor(pubspecYaml);

packages/aft/lib/src/config/config_loader.dart

@@ -55,29 +55,6 @@ class AftConfigLoader {
     return reload();
   }
 
-  Map<String, PackageInfo> _collectPackages({
-    required Directory rootDirectory,
-    required List<String> ignore,
-  }) {
-    final allDirs = rootDirectory
-        .listSync(recursive: true, followLinks: false)
-        .whereType<Directory>();
-    final allPackages = <PackageInfo>[];
-    for (final dir in allDirs) {
-      final package = PackageInfo.fromDirectory(dir);
-      if (package == null) {
-        continue;
-      }
-      if (ignore.contains(package.name)) {
-        continue;
-      }
-      allPackages.add(package);
-    }
-    return UnmodifiableMapView({
-      for (final package in allPackages..sort()) package.name: package,
-    });
-  }
-
   AftConfig _processPubspecs({
     required Queue<(YamlMap, Pubspec)> pubspecQueue,
     required Directory rootDirectory,
@@ -180,4 +157,26 @@ class AftConfigLoader {
 
     return aftConfig.build();
   }
+
+  /// Collects all packages in [rootDirectory] by recursively searching for directories
+  /// with a `pubspec.yaml`.
+  Map<String, PackageInfo> _collectPackages({
+    required Directory rootDirectory,
+    required List<String> ignore,
+  }) {
+    final allDirs = rootDirectory
+        .listSync(recursive: true, followLinks: false)
+        .whereType<Directory>();
+    final allPackages = <PackageInfo>[];
+    for (final dir in allDirs) {
+      final package = PackageInfo.fromDirectory(dir);
+      if (package == null || ignore.contains(package.name)) {
+        continue;
+      }
+      allPackages.add(package);
+    }
+    return UnmodifiableMapView({
+      for (final package in allPackages..sort()) package.name: package,
+    });
+  }
 }

packages/aft/lib/src/config/raw_config.dart

@@ -75,6 +75,7 @@ class RawAftConfig with AWSSerializable<Map<String, Object?>>, AWSDebuggable {
     this.ignore = const [],
     this.components = const [],
     this.scripts = const {},
+    this.github,
   });
 
   factory RawAftConfig.fromJson(Map<String, Object?> json) =>
@@ -89,8 +90,12 @@ class RawAftConfig with AWSSerializable<Map<String, Object?>>, AWSDebuggable {
   /// {@macro aft.models.aft_component}
   final List<RawAftComponent> components;
 
+  /// Package- or repo-specific [AftScript]s.
   final Map<String, AftScript> scripts;
 
+  /// Package-specific GitHub configuration.
+  final GitHubPackageConfig? github;
+
   /// Retrieves the component for [packageName], if any.
   String componentForPackage(String packageName) {
     return components
@@ -268,6 +273,46 @@ abstract class MacOSEnvironment
       _$macOSEnvironmentSerializer;
 }
 
+abstract class GitHubPackageConfig
+    with AWSSerializable<Map<String, Object?>>, AWSDebuggable
+    implements Built<GitHubPackageConfig, GitHubPackageConfigBuilder> {
+  factory GitHubPackageConfig({
+    bool custom = false,
+  }) =>
+      _$GitHubPackageConfig._(custom: custom);
+
+  factory GitHubPackageConfig.build(
+    void Function(GitHubPackageConfigBuilder) updates,
+  ) = _$GitHubPackageConfig;
+
+  factory GitHubPackageConfig.fromJson(Map<String, Object?> json) =>
+      aftSerializers.deserializeWith(serializer, json)!;
+
+  const GitHubPackageConfig._();
+
+  @BuiltValueHook(initializeBuilder: true)
+  static void _initialize(GitHubPackageConfigBuilder b) {
+    b.custom = false;
+  }
+
+  /// Whether a custom workflow is being used.
+  ///
+  /// If this is `false`, one will be generated during `aft generate workflows`.
+  /// Otherwise, an assertion will be made that one is present for `package_name.yaml`
+  /// in the `.github/workflows` directory.
+  bool get custom;
+
+  @override
+  String get runtimeTypeName => 'GitHubPackageConfig';
+
+  @override
+  Map<String, Object?> toJson() =>
+      aftSerializers.serializeWith(serializer, this) as Map<String, Object?>;
+
+  static Serializer<GitHubPackageConfig> get serializer =>
+      _$gitHubPackageConfigSerializer;
+}
+
 /// Specifies how to propagate version changes within a component.
 enum VersionPropagation {
   /// Propagates only major version changes.

packages/aft/lib/src/config/serializers.dart

@@ -17,6 +17,7 @@ part 'serializers.g.dart';
   AndroidEnvironment,
   IosEnvironment,
   MacOSEnvironment,
+  GitHubPackageConfig,
 ])
 final Serializers aftSerializers = (_$aftSerializers.toBuilder()
       ..addPlugin(StandardJsonPlugin())

packages/aft/pubspec.yaml

@@ -73,3 +73,7 @@ dev_dependencies:
 
 executables:
   aft:
+
+aft:
+  github:
+    custom: true