Add vmservice for android build options (#123034)

flutter/flutter#120408

Author: chunhtai

packages/flutter_tools/gradle/flutter.gradle

@@ -695,6 +695,28 @@ class FlutterPlugin implements Plugin<Project> {
         }
     }
 
+    // Add a task that can be called on flutter projects that prints the available build variants
+    // in gradle.
+    //
+    // This task prints variants in this format:
+    //
+    // BuildVariant: debug
+    // BuildVariant: release
+    // BuildVariant: profile
+    //
+    // Format of the output of this task is used by `AndroidProject.getBuildVariants`.
+    private static void addTaskForPrintBuildVariants(Project project) {
+        // Warning: The name of this task is used by `AndroidProject.getBuildVariants`.
+        project.tasks.register("printBuildVariants") {
+            description "Prints out all build variants for this Android project"
+            doLast {
+                project.android.applicationVariants.all { variant ->
+                    println "BuildVariant: ${variant.name}";
+                }
+            }
+        }
+    }
+
     /**
      * Returns a Flutter build mode suitable for the specified Android buildType.
      *
@@ -867,7 +889,9 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('validate-deferred-components')) {
             validateDeferredComponentsValue = project.property('validate-deferred-components').toBoolean()
         }
+
         addTaskForJavaVersion(project)
+        addTaskForPrintBuildVariants(project)
         def targetPlatforms = getTargetPlatforms()
         def addFlutterDeps = { variant ->
             if (shouldSplitPerAbi()) {

packages/flutter_tools/lib/src/android/android_builder.dart

@@ -39,4 +39,7 @@ abstract class AndroidBuilder {
     bool deferredComponentsEnabled = false,
     bool configOnly = false,
   });
+
+  /// Returns a list of available build variant from the Android project.
+  Future<List<String>> getBuildVariants({required FlutterProject project});
 }

packages/flutter_tools/lib/src/android/android_sdk.dart

@@ -40,7 +40,7 @@ class AndroidSdk {
     reinitialize();
   }
 
-  static const String _javaHomeEnvironmentVariable = 'JAVA_HOME';
+  static const String javaHomeEnvironmentVariable = 'JAVA_HOME';
   static const String _javaExecutable = 'java';
 
   /// The Android SDK root directory.
@@ -462,10 +462,44 @@ class AndroidSdk {
     return versionString.split('_').first;
   }
 
-  /// Finds the java binary that is used for all operations across the tool.
+  /// A value that would be appropriate to use as JAVA_HOME.
   ///
-  /// First try Java bundled with Android Studio, then sniff JAVA_HOME, then fallback to PATH.
+  /// This method considers jdk in the following order:
+  /// * the JDK bundled with Android Studio, if one is found;
+  /// * the JAVA_HOME in the ambient environment, if set;
+  String? get javaHome {
+    return findJavaHome(
+      androidStudio: globals.androidStudio,
+      fileSystem: globals.fs,
+      operatingSystemUtils: globals.os,
+      platform: globals.platform,
+    );
+  }
+
+
+  static String? findJavaHome({
+    required AndroidStudio? androidStudio,
+    required FileSystem fileSystem,
+    required OperatingSystemUtils operatingSystemUtils,
+    required Platform platform,
+  }) {
+    if (androidStudio?.javaPath != null) {
+      globals.printTrace("Using Android Studio's java.");
+      return androidStudio!.javaPath!;
+    }
+
+    final String? javaHomeEnv = platform.environment[javaHomeEnvironmentVariable];
+    if (javaHomeEnv != null) {
+      globals.printTrace('Using JAVA_HOME from environment valuables.');
+      return javaHomeEnv;
+    }
+    return null;
+  }
+
+  /// Finds the java binary that is used for all operations across the tool.
   ///
+  /// This comes from [findJavaHome] if that method returns non-null;
+  /// otherwise, it gets from searching PATH.
   // TODO(andrewkolos): To prevent confusion when debugging Android-related
   // issues (see https://github.com/flutter/flutter/issues/122609 for an example),
   // this logic should be consistently followed by any Java-dependent operation
@@ -479,17 +513,15 @@ class AndroidSdk {
     required OperatingSystemUtils operatingSystemUtils,
     required Platform platform,
   }) {
-    if (androidStudio?.javaPath != null) {
-      globals.printTrace("Using Android Studio's java.");
-      return fileSystem.path.join(androidStudio!.javaPath!, 'bin', 'java');
-    }
+    final String? javaHome = findJavaHome(
+      androidStudio: androidStudio,
+      fileSystem: fileSystem,
+      operatingSystemUtils: operatingSystemUtils,
+      platform: platform,
+    );
 
-    final String? javaHomeEnv =
-        platform.environment[_javaHomeEnvironmentVariable];
-    if (javaHomeEnv != null) {
-      // Trust JAVA_HOME.
-      globals.printTrace('Using JAVA_HOME.');
-      return fileSystem.path.join(javaHomeEnv, 'bin', 'java');
+    if (javaHome != null) {
+      return fileSystem.path.join(javaHome, 'bin', 'java');
     }
 
     // Fallback to PATH based lookup.
@@ -528,8 +560,8 @@ class AndroidSdk {
       );
       if (javaBinary != null && globals.platform.environment['PATH'] != null) {
         _sdkManagerEnv!['PATH'] = globals.fs.path.dirname(javaBinary) +
-                                 globals.os.pathVarSeparator +
-                                 globals.platform.environment['PATH']!;
+                                  globals.os.pathVarSeparator +
+                                  globals.platform.environment['PATH']!;
       }
     }
     return _sdkManagerEnv!;

packages/flutter_tools/lib/src/android/gradle.dart

@@ -26,15 +26,28 @@ import '../build_info.dart';
 import '../cache.dart';
 import '../convert.dart';
 import '../flutter_manifest.dart';
+import '../globals.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
 import 'android_builder.dart';
-import 'android_studio.dart';
+import 'android_sdk.dart';
 import 'gradle_errors.dart';
 import 'gradle_utils.dart';
 import 'migrations/top_level_gradle_build_file_migration.dart';
 import 'multidex.dart';
 
+/// The regex to grab variant names from printVariants gradle task
+///
+/// The task is defined in flutter/packages/flutter_tools/gradle/flutter.gradle.
+///
+/// The expected output from the task should be similar to:
+///
+/// BuildVariant: debug
+/// BuildVariant: release
+/// BuildVariant: profile
+final RegExp _kBuildVariantRegex = RegExp('^BuildVariant: (?<$_kBuildVariantRegexGroupName>.*)\$');
+const String _kBuildVariantRegexGroupName = 'variant';
+
 /// The directory where the APK artifact is generated.
 Directory getApkDirectory(FlutterProject project) {
   return project.isModule
@@ -397,13 +410,14 @@ class AndroidGradleBuilder implements AndroidBuilder {
       ..start();
     int exitCode = 1;
     try {
+      final String? javaHome = globals.androidSdk?.javaHome;
       exitCode = await _processUtils.stream(
         command,
         workingDirectory: project.android.hostAppGradleRoot.path,
         allowReentrantFlutter: true,
         environment: <String, String>{
-          if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
         },
         mapFunction: consumeLog,
       );
@@ -666,13 +680,14 @@ class AndroidGradleBuilder implements AndroidBuilder {
       ..start();
     RunResult result;
     try {
+      final String? javaHome = globals.androidSdk?.javaHome;
       result = await _processUtils.run(
         command,
         workingDirectory: project.android.hostAppGradleRoot.path,
         allowReentrantFlutter: true,
         environment: <String, String>{
-          if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
         },
       );
     } finally {
@@ -702,6 +717,51 @@ class AndroidGradleBuilder implements AndroidBuilder {
       color: TerminalColor.green,
     );
   }
+
+  @override
+  Future<List<String>> getBuildVariants({required FlutterProject project}) async {
+    final Status status = _logger.startProgress(
+      "Running Gradle task 'printBuildVariants'...",
+    );
+    final List<String> command = <String>[
+      _gradleUtils.getExecutable(project),
+      '-q', // suppresses gradle output.
+      'printBuildVariants',
+    ];
+
+    final Stopwatch sw = Stopwatch()
+      ..start();
+    RunResult result;
+    try {
+      final String? javaHome = globals.androidSdk?.javaHome;
+      result = await _processUtils.run(
+        command,
+        workingDirectory: project.android.hostAppGradleRoot.path,
+        allowReentrantFlutter: true,
+        environment: <String, String>{
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
+        },
+      );
+    } finally {
+      status.stop();
+    }
+    _usage.sendTiming('print', 'android build variants', sw.elapsed);
+
+    if (result.exitCode != 0) {
+      _logger.printStatus(result.stdout, wrap: false);
+      _logger.printError(result.stderr, wrap: false);
+      return const <String>[];
+    }
+    final List<String> options = <String>[];
+    for (final String line in LineSplitter.split(result.stdout)) {
+      final RegExpMatch? match = _kBuildVariantRegex.firstMatch(line);
+      if (match != null) {
+        options.add(match.namedGroup(_kBuildVariantRegexGroupName)!);
+      }
+    }
+    return options;
+  }
 }
 
 /// Prints how to consume the AAR from a host app.

packages/flutter_tools/lib/src/android/gradle_errors.dart

@@ -11,6 +11,7 @@ import '../base/terminal.dart';
 import '../globals.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
+import 'android_sdk.dart';
 import 'android_studio.dart';
 import 'gradle_utils.dart';
 import 'multidex.dart';
@@ -379,7 +380,7 @@ final GradleHandledError flavorUndefinedHandler = GradleHandledError(
       workingDirectory: project.android.hostAppGradleRoot.path,
       environment: <String, String>{
         if (javaPath != null)
-          'JAVA_HOME': javaPath!,
+          AndroidSdk.javaHomeEnvironmentVariable: javaPath!,
       },
     );
     // Extract build types and product flavors.

packages/flutter_tools/lib/src/flutter_cache.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:meta/meta.dart';
 import 'package:package_config/package_config.dart';
 
+import 'android/android_sdk.dart';
 import 'android/android_studio.dart';
 import 'base/common.dart';
 import 'base/error_handling_io.dart';
@@ -425,7 +426,7 @@ class AndroidMavenArtifacts extends ArtifactSet {
         ],
         environment: <String, String>{
           if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+            AndroidSdk.javaHomeEnvironmentVariable: javaPath!,
         },
       );
       if (processResult.exitCode != 0) {

packages/flutter_tools/lib/src/project.dart

@@ -7,6 +7,7 @@ import 'package:xml/xml.dart';
 import 'package:yaml/yaml.dart';
 
 import '../src/convert.dart';
+import 'android/android_builder.dart';
 import 'android/gradle_utils.dart' as gradle;
 import 'base/common.dart';
 import 'base/error_handling_io.dart';
@@ -474,6 +475,13 @@ class AndroidProject extends FlutterProjectPlatform {
   /// Returns true if the current version of the Gradle plugin is supported.
   late final bool isSupportedVersion = _computeSupportedVersion();
 
+  Future<List<String>> getBuildVariants() async {
+    if (!existsSync() || androidBuilder == null) {
+      return const <String>[];
+    }
+    return androidBuilder!.getBuildVariants(project: parent);
+  }
+
   bool _computeSupportedVersion() {
     final FileSystem fileSystem = hostAppGradleRoot.fileSystem;
     final File plugin = hostAppGradleRoot.childFile(