Android

This guide covers building godot-bevy projects for Android devices. Android development requires cross-compilation from your development machine to ARM64 architecture used by most modern Android devices.

Prerequisites

Android NDK - The Native Development Kit provides the compilers and tools needed to build native code for Android. Download from Android NDK Downloads
Rust target - Install the Android ARM64 compilation target for Rust:
```
rustup target add aarch64-linux-android
```

Step 1: Configure Build Environment

The Rust cc build system needs explicit paths to Android NDK compilers for cross-compilation. This tells Rust which Android-specific compilers to use instead of your system's default compilers.

Option A: Environment Variables

Set these once per terminal session:

export NDK_HOME="/path/to/your/android/ndk"
export CC="$NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android21-clang"
export CXX="$NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android21-clang++"
export AR="$NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-ar"

Option B: Inline Command

Self-contained approach that doesn't modify your shell environment:

CC="$NDK_HOME/..." CXX="$NDK_HOME/..." AR="$NDK_HOME/..." cargo build --target aarch64-linux-android

Step 2: Configure Cargo Linker

Create .cargo/config.toml in your rust/ directory. This tells Cargo how to link the compiled code into Android-compatible libraries:

[target.aarch64-linux-android]
linker = "/path/to/your/android/ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android21-clang"
ar = "/path/to/your/android/ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-ar"

Step 3: Modify Entry Point

Android requires a specific entry point function name. Change your Bevy app entry point (likely lib.rs) from:

#![allow(unused)]
fn main() {
#[bevy_app]
fn build_bevy_app(app: &mut App) {
    // ...
}
}

To:

#![allow(unused)]
fn main() {
#[bevy_app]
#[no_mangle]
fn android_main(app: &mut App) {
    // ...
}
}

The #[no_mangle] attribute prevents Rust from changing the function name during compilation, ensuring Android can find the entry point.

Step 4: Build for Android

Build your Rust library for Android:

cargo build --target aarch64-linux-android

or use the self-contained command from above if you haven't setup the envs.

This creates a shared library file lib{your_app_name}.so in rust/target/aarch64-linux-android/debug/ that Android can load.

Step 5: Update Godot Configuration

Update rust.gdextension

Tell Godot where to find your Android library by adding these paths to your rust.gdextension file:

[libraries]
# ... existing entries ...
android.debug.arm64 = "res://rust/target/aarch64-linux-android/debug/lib{your_app_name}.so"
android.release.arm64 = "res://rust/target/aarch64-linux-android/release/lib{your_app_name}.so"

Configure Godot Export

Go to Project → Export...
Select Android preset
Under Architectures, ensure arm64-v8a is selected

Note: The Rust target aarch64-linux-android corresponds to Android's arm64-v8a architecture

Export your app and deploy to your Android device.

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