Add Android release binaries to CI

.github/actions/android-ndk/action.yml

@@ -0,0 +1,31 @@
+# This is a small action which uses the pre-installed Android NDK on GitHub
+# Actions builders, configured with `$ANDROID_NDK`, to compile and link Android
+# code. For Rust we mostly need to configure the linker to Cargo and the C
+# compiler to the `cc` crate, so this sets various environment variables to the
+# appropriate tool within `$ANDROID_NDK`.
+
+name: 'Setup Rust to use the Android NDK'
+description: 'Setup Rust to use the android NDK'
+
+inputs:
+  target:
+    description: 'Rust target being used'
+    required: true
+  android-platform:
+    description: 'Platform version to use for the C compiler'
+    required: false
+    default: '26'
+
+runs:
+  using: composite
+  steps:
+    - run: |
+        target=${{ inputs.target }}
+        upcase=$(echo $target | tr a-z- A-Z_)
+        ndk_bin=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64/bin
+        linker=$ndk_bin/${target}${{ inputs.android-platform }}-clang
+        echo CARGO_TARGET_${upcase}_LINKER=$linker >> $GITHUB_ENV
+        echo CC_${target}=$linker >> $GITHUB_ENV
+        echo RANLIB_${target}=$ndk_bin/llvm-ranlib >> $GITHUB_ENV
+        echo AR_${target}=$ndk_bin/llvm-ar >> $GITHUB_ENV
+      shell: bash

.github/actions/binary-compatible-builds/main.js

@@ -21,6 +21,12 @@ if (process.platform == 'win32') {
   return;
 }
 
+// Android doesn't use a container as it's controlled by the installation of the
+// SDK/NDK.
+if (process.env.INPUT_NAME && process.env.INPUT_NAME.indexOf("android") >= 0) {
+  return;
+}
+
 // ... and on Linux we do fancy things with containers. We'll spawn an old
 // CentOS container in the background with a super old glibc, and then we'll run
 // commands in there with the `$CENTOS` env var.

.github/workflows/main.yml

@@ -306,8 +306,6 @@ jobs:
     needs: determine
     name: Check
     runs-on: ubuntu-latest
-    env:
-      CARGO_NDK_VERSION: 2.12.2
     steps:
     - uses: actions/checkout@v4
       with:
@@ -389,23 +387,6 @@ jobs:
     - run: rustup target add x86_64-unknown-freebsd
     - run: cargo check -p wasmtime --no-default-features --features cranelift,wat,async,cache --target x86_64-unknown-freebsd
 
-    # Check whether `wasmtime` cross-compiles to aarch64-linux-android
-    - run: rustup target add aarch64-linux-android
-    - name: Set up JDK 17
-      uses: actions/setup-java@v4
-      with:
-        java-version: '17'
-        distribution: 'temurin'
-    - name: Setup Android SDK
-      uses: android-actions/setup-android@v3
-    - uses: actions/cache@v4
-      with:
-        path: ${{ runner.tool_cache }}/cargo-ndk
-        key: cargo-ndk-bin-${{ env.CARGO_NDK_VERSION }}
-    - run: echo "${{ runner.tool_cache }}/cargo-ndk/bin" >> $GITHUB_PATH
-    - run: cargo install --root ${{ runner.tool_cache }}/cargo-ndk --version ${{ env.CARGO_NDK_VERSION }} cargo-ndk --locked
-    - run: cargo ndk -t arm64-v8a check -p wasmtime
-
     # Run clippy configuration
     - run: rustup component add clippy
     - run: cargo clippy --workspace
@@ -881,6 +862,11 @@ jobs:
       with:
         name: ${{ matrix.build }}
 
+    - uses: ./.github/actions/android-ndk
+      if: contains(matrix.target, 'android')
+      with:
+        target: ${{ matrix.target }}
+
     - run: $CENTOS ./ci/build-release-artifacts.sh "${{ matrix.build }}" "${{ matrix.target }}"
 
     # Assemble release artifacts appropriate for this platform, then upload them

ci/build-build-matrix.js

@@ -49,6 +49,16 @@ const array = [
     "os": "windows-latest",
     "target": "x86_64-pc-windows-gnu",
   },
+  {
+    "build": "aarch64-android",
+    "os": "ubuntu-latest",
+    "target": "aarch64-linux-android",
+  },
+  {
+    "build": "x86_64-android",
+    "os": "ubuntu-latest",
+    "target": "x86_64-linux-android",
+  },
 ];
 
 const builds = [];

docs/stability-tiers.md

@@ -89,6 +89,8 @@ For explanations of what each tier means see below.
 | Target               | `aarch64-pc-windows-msvc`         | CI testing, unwinding, full-time maintainer |
 | Target               | `riscv64gc-unknown-linux-gnu`     | full-time maintainer        |
 | Target               | `wasm32-wasi` [^3]                | Supported but not tested    |
+| Target               | `aarch64-linux-android`           | CI testing, full-time maintainer |
+| Target               | `x86_64-linux-android`            | CI testing, full-time maintainer |
 | Compiler Backend     | Winch on aarch64                  | finished implementation     |
 | WebAssembly Proposal | [`gc`]                            | Complete implementation     |
 | WASI Proposal        | [`wasi-nn`]                       | More expansive CI testing   |