Make android buildable under bazel

.bazelrc

@@ -1 +1,7 @@
 build --cxxopt=-std=c++17 --host_cxxopt=-std=c++17
+
+# Enforce stable JDK 17 compilation globally (aligns with rules_android defaults)
+common --java_language_version=17
+common --java_runtime_version=17
+common --tool_java_language_version=17
+common --tool_java_runtime_version=17

.github/workflows/testing.yml

@@ -81,7 +81,7 @@ jobs:
       matrix:
         bzlmod: [true, false]
     env:
-      USE_BAZEL_VERSION: 7.7.1
+      USE_BAZEL_VERSION: 8.7.0
 
     steps:
     - uses: actions/checkout@v4
@@ -100,11 +100,11 @@ jobs:
         key: ${{ runner.os }}-bazel-${{ env.USE_BAZEL_VERSION }}-${{ hashFiles('WORKSPACE', 'repositories.bzl') }}
 
     - name: Run bazel build
-      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
 
     - name: Run bazel test
-      run: bazelisk test //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk test //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
 
     - name: Run example bazel build
-      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
       working-directory: ./examples

MODULE.bazel

@@ -1,7 +1,6 @@
 module(
     name = "grpc-java",
     version = "1.82.0-SNAPSHOT",  # CURRENT_GRPC_VERSION
-    compatibility_level = 0,
     repo_name = "io_grpc_grpc_java",
 )
 
@@ -53,6 +52,7 @@ bazel_dep(name = "bazel_skylib", version = "1.7.1")
 bazel_dep(name = "googleapis", version = "0.0.0-20240326-1c8d509c5", repo_name = "com_google_googleapis")
 bazel_dep(name = "grpc-proto", version = "0.0.0-20240627-ec30f58.bcr.1", repo_name = "io_grpc_grpc_proto")
 bazel_dep(name = "protobuf", version = "33.4", repo_name = "com_google_protobuf")
+bazel_dep(name = "rules_android", version = "0.6.0")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "rules_java", version = "9.1.0")
 bazel_dep(name = "rules_jvm_external", version = "6.0")

WORKSPACE

@@ -17,6 +17,7 @@ load("@com_google_protobuf//:protobuf_deps.bzl", "PROTOBUF_MAVEN_ARTIFACTS", "pr
 
 protobuf_deps()
 
+# Register remote JDK toolchains to safely compile Java targets under Bazel 8.
 load("@rules_java//java:rules_java_deps.bzl", "rules_java_dependencies")
 
 rules_java_dependencies()
@@ -25,6 +26,11 @@ load("@bazel_features//:deps.bzl", "bazel_features_deps")
 
 bazel_features_deps()
 
+# Must be loaded after bazel_features_deps() to avoid circular deps.
+load("@rules_java//java:repositories.bzl", "rules_java_toolchains")
+
+rules_java_toolchains()
+
 load("@bazel_jar_jar//:jar_jar.bzl", "jar_jar_repositories")
 
 jar_jar_repositories()
@@ -49,10 +55,119 @@ http_archive(
 load("@rules_jvm_external//:defs.bzl", "maven_install")
 
 maven_install(
-    artifacts = IO_GRPC_GRPC_JAVA_ARTIFACTS + PROTOBUF_MAVEN_ARTIFACTS,
+    artifacts = IO_GRPC_GRPC_JAVA_ARTIFACTS + PROTOBUF_MAVEN_ARTIFACTS + [
+    # Hack: Android compile-time worker ResourceProcessorBusyBox uses protos internally.
+    # This ensures rules_jvm_external generates its namespace target alias,
+    # enabling the IO_GRPC_GRPC_JAVA_OVERRIDE_TARGETS to override it correctly.
+        "com.google.protobuf:protobuf-java-util:3.25.5",
+    ],
     override_targets = IO_GRPC_GRPC_JAVA_OVERRIDE_TARGETS,
     repositories = [
         "https://repo.maven.apache.org/maven2/",
+        # For androidx deps (e.g. core) not published to Maven Central.
+        "https://maven.google.com",
     ],
     strict_visibility = True,
 )
+
+# Define a custom rules_android_maven repository to override its com.google.protobuf
+# runtime dependency to point directly to our workspace compiled C++ target.
+# This resolves severe runtime-vs-gencode validation crashes inside the precompiled
+# ResourceProcessorBusyBox tool when executing under legacy workspace mode.
+maven_install(
+    name = "rules_android_maven",
+    artifacts = [
+        "androidx.privacysandbox.tools:tools:1.0.0-alpha06",
+        "androidx.privacysandbox.tools:tools-apigenerator:1.0.0-alpha06",
+        "androidx.privacysandbox.tools:tools-apipackager:1.0.0-alpha06",
+        "androidx.test:core:1.6.0-alpha01",
+        "androidx.test.ext:junit:1.2.0-alpha01",
+        "com.android.tools.apkdeployer:apkdeployer:8.8.0-alpha05",
+        "org.gradle:gradle-core:4.2.1",
+        "com.android.tools.build:bundletool:1.15.5",
+        "com.android.tools:desugar_jdk_libs_minimal:2.0.4",
+        "com.android.tools:desugar_jdk_libs_configuration_minimal:2.0.4",
+        "com.android.tools:desugar_jdk_libs_nio:2.0.4",
+        "com.android.tools:desugar_jdk_libs_configuration_nio:2.0.4",
+        "com.android.tools.build:gradle:8.7.0",
+        "com.android.tools:r8:8.5.35",
+        "org.bouncycastle:bcprov-jdk18on:1.77",
+        "org.hamcrest:hamcrest-core:2.2",
+        "org.robolectric:robolectric:4.14.1",
+        "com.google.flogger:flogger:0.8",
+        "com.google.guava:guava:32.1.2-jre",
+        "com.google.truth:truth:1.1.5",
+        "info.picocli:picocli:4.7.4",
+        "jakarta.inject:jakarta.inject-api:2.0.1",
+        "junit:junit:4.13.2",
+        "com.beust:jcommander:1.82",
+        "com.google.protobuf:protobuf-java:3.25.5",
+        "com.google.protobuf:protobuf-java-util:3.25.5",
+        "com.google.code.findbugs:jsr305:3.0.2",
+        "androidx.databinding:databinding-compiler:8.7.0",
+        "org.ow2.asm:asm:9.6",
+        "org.ow2.asm:asm-commons:9.6",
+        "org.ow2.asm:asm-tree:9.6",
+        "org.ow2.asm:asm-util:9.6",
+        "com.android.tools.layoutlib:layoutlib-api:30.1.3",
+        "com.android:zipflinger:8.7.0",
+        "com.android.tools.build:manifest-merger:30.1.3",
+        "com.android:signflinger:8.7.0",
+        "com.android.tools.build:aapt2-proto:8.6.1-11315950",
+        "com.android.tools.analytics-library:protos:30.1.3",
+        "com.android.tools.analytics-library:shared:30.1.3",
+        "com.android.tools.analytics-library:tracker:30.1.3",
+        "com.android.tools:annotations:30.1.3",
+        "com.android.tools.build:apksig:8.7.0",
+        "com.android.tools.build:apkzlib:8.7.0",
+        "com.android.tools.build:builder:8.7.0",
+        "com.android.tools.build:builder-model:8.7.0",
+        "com.google.auto.value:auto-value:1.11.0",
+        "com.google.auto.value:auto-value-annotations:1.11.0",
+        "com.google.auto:auto-common:1.2.2",
+        "com.google.auto.service:auto-service:1.1.1",
+        "com.google.auto.service:auto-service-annotations:1.1.1",
+        "com.google.errorprone:error_prone_annotations:2.33.0",
+        "com.google.errorprone:error_prone_type_annotations:2.33.0",
+        "com.google.errorprone:error_prone_check_api:2.33.0",
+        "com.google.errorprone:error_prone_core:2.33.0",
+    ],
+    override_targets = {
+        "com.google.protobuf:protobuf-java": "@com_google_protobuf//:protobuf_java",
+        "com.google.protobuf:protobuf-java-util": "@com_google_protobuf//:protobuf_java_util",
+    },
+    repositories = [
+        "https://repo1.maven.org/maven2",
+        "https://maven.google.com",
+        "https://repo.gradle.org/gradle/libs-releases",
+    ],
+    use_starlark_android_rules = True,
+    aar_import_bzl_label = "@rules_android//rules:rules.bzl",
+)
+
+# Download rules_android prerequisite repositories (such as @robolectric,
+# @io_bazel_rules_go, and @bazel_gazelle). This MUST be executed before loading
+# @rules_android//:defs.bzl to resolve top-level circular Starlark load statements.
+load("@rules_android//:prereqs.bzl", "rules_android_prereqs")
+
+rules_android_prereqs()
+
+load("@rules_android//:defs.bzl", "rules_android_workspace")
+
+rules_android_workspace()
+
+load("@rules_android//rules/android_sdk_repository:rule.bzl", "android_sdk_repository")
+
+android_sdk_repository(
+    name = "androidsdk",
+)
+
+# Register Android and SDK toolchains.
+# Note: @rules_android//toolchains/android_sdk:android_sdk_tools is required
+# to bridge legacy generated `@androidsdk` toolchains to modern standalone
+# rules_android toolchain type expectations under legacy workspace mode.
+register_toolchains(
+    "@androidsdk//:all",
+    "@rules_android//toolchains/android:all",
+    "@rules_android//toolchains/android_sdk:android_sdk_tools",
+)

android/BUILD.bazel

@@ -0,0 +1,19 @@
+load("@rules_android//rules:rules.bzl", "android_library")
+load("@rules_jvm_external//:defs.bzl", "artifact")
+
+android_library(
+    name = "android",
+    srcs = glob([
+        "src/main/java/**/*.java",
+    ]),
+    custom_package = "io.grpc.android",
+    manifest = "src/main/AndroidManifest.xml",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//api",
+        "//core:internal",
+        artifact("com.google.code.findbugs:jsr305"),
+        artifact("com.google.errorprone:error_prone_annotations"),
+        artifact("com.google.guava:guava"),
+    ],
+)

examples/MODULE.bazel

@@ -2,6 +2,8 @@ bazel_dep(name = "grpc-java", version = "1.82.0-SNAPSHOT", repo_name = "io_grpc_
 bazel_dep(name = "rules_java", version = "9.3.0")
 bazel_dep(name = "grpc-proto", version = "0.0.0-20240627-ec30f58", repo_name = "io_grpc_grpc_proto")
 bazel_dep(name = "protobuf", version = "33.1", repo_name = "com_google_protobuf")
+bazel_dep(name = "rules_android", version = "0.6.0")
+bazel_dep(name = "rules_proto", version = "7.1.0")
 bazel_dep(name = "rules_jvm_external", version = "6.0")
 
 # Do not use this override in your own MODULE.bazel. It is unnecessary when
@@ -26,7 +28,11 @@ maven.install(
     artifacts = [
         "com.google.api.grpc:grpc-google-cloud-pubsub-v1:0.1.24",
         "com.google.api.grpc:proto-google-cloud-pubsub-v1:0.1.24",
+        "androidx.appcompat:appcompat:1.0.0",
+    ],
+    repositories = [
+        "https://repo.maven.apache.org/maven2/",
+        "https://maven.google.com",
     ],
-    repositories = ["https://repo.maven.apache.org/maven2/"],
     strict_visibility = True,
 )

examples/android/helloworld/app/BUILD.bazel

@@ -0,0 +1,42 @@
+load("@rules_android//rules:rules.bzl", "android_binary")
+load("@io_grpc_grpc_java//:java_grpc_library.bzl", "java_grpc_library")
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@rules_java//java:defs.bzl", "java_lite_proto_library")
+
+proto_library(
+    name = "helloworld_proto",
+    srcs = ["src/main/proto/helloworld.proto"],
+)
+
+java_lite_proto_library(
+    name = "helloworld_java_proto_lite",
+    deps = [":helloworld_proto"],
+)
+
+java_grpc_library(
+    name = "helloworld_java_grpc_lite",
+    srcs = [":helloworld_proto"],
+    flavor = "lite",
+    deps = [":helloworld_java_proto_lite"],
+)
+
+android_binary(
+    name = "app",
+    srcs = glob([
+        "src/main/java/**/*.java",
+    ]),
+    custom_package = "io.grpc.helloworldexample",
+    manifest = "src/main/AndroidManifest.xml",
+    resource_files = glob(["src/main/res/**"]),
+    visibility = ["//visibility:public"],
+    deps = [
+        ":helloworld_java_grpc_lite",
+        ":helloworld_java_proto_lite",
+        "@io_grpc_grpc_java//api",
+        "@io_grpc_grpc_java//android",
+        "@io_grpc_grpc_java//okhttp",
+        "@io_grpc_grpc_java//protobuf-lite",
+        "@io_grpc_grpc_java//stub",
+        "@maven//:androidx_appcompat_appcompat",
+    ],
+)

examples/android/helloworld/app/build.gradle

@@ -55,4 +55,5 @@ dependencies {
     implementation 'io.grpc:grpc-okhttp:1.82.0-SNAPSHOT' // CURRENT_GRPC_VERSION
     implementation 'io.grpc:grpc-protobuf-lite:1.82.0-SNAPSHOT' // CURRENT_GRPC_VERSION
     implementation 'io.grpc:grpc-stub:1.82.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-android:1.82.0-SNAPSHOT' // CURRENT_GRPC_VERSION
 }

examples/android/helloworld/app/src/main/java/io/grpc/helloworldexample/HelloworldActivity.java

@@ -29,7 +29,7 @@
 import android.widget.EditText;
 import android.widget.TextView;
 import io.grpc.ManagedChannel;
-import io.grpc.ManagedChannelBuilder;
+import io.grpc.android.AndroidChannelBuilder;
 import io.grpc.examples.helloworld.GreeterGrpc;
 import io.grpc.examples.helloworld.HelloReply;
 import io.grpc.examples.helloworld.HelloRequest;
@@ -91,7 +91,12 @@ protected String doInBackground(String... params) {
       String portStr = params[2];
       int port = TextUtils.isEmpty(portStr) ? 0 : Integer.valueOf(portStr);
       try {
-        channel = ManagedChannelBuilder.forAddress(host, port).usePlaintext().build();
+        Activity activity = activityReference.get();
+        AndroidChannelBuilder channelBuilder = AndroidChannelBuilder.forAddress(host, port);
+        if (activity != null) {
+          channelBuilder.context(activity.getApplicationContext());
+        }
+        channel = channelBuilder.usePlaintext().build();
         GreeterGrpc.GreeterBlockingStub stub = GreeterGrpc.newBlockingStub(channel);
         HelloRequest request = HelloRequest.newBuilder().setName(message).build();
         HelloReply reply = stub.sayHello(request);

repositories.bzl

@@ -110,6 +110,13 @@ def grpc_java_repositories():
             strip_prefix = "bazel_jar_jar-0.1.6",
             url = "https://github.com/bazeltools/bazel_jar_jar/releases/download/v0.1.6/bazel_jar_jar-v0.1.6.tar.gz",
         )
+    if not native.existing_rule("rules_android"):
+        http_archive(
+            name = "rules_android",
+            sha256 = "af84b69ab3d16dd1a41056286e6511f147a94ccea995603e13e934c915c1631c",
+            strip_prefix = "rules_android-0.6.0",
+            urls = ["https://github.com/bazelbuild/rules_android/releases/download/v0.6.0/rules_android-v0.6.0.tar.gz"],
+        )
 
 def com_google_protobuf():
     # proto_library rules implicitly depend on @com_google_protobuf//:protoc,