Building Pumpkin Launcher

This covers building the native Pumpkin server binaries, packaging the Android app, and installing it — all from a terminal.

Shortcut: skip building the native binaries entirely

Pre-built Android binaries (libpumpkin.so for arm64-v8a, armeabi-v7a, and x86_64) are published on this repo's Releases page. If you just want to build the app itself, download those and skip straight to Step 2: Copy the binaries into the Android project below — no Rust toolchain, NDK, or cargo-ndk setup needed at all.

Only follow Step 1 if you want to compile the native binaries yourself (e.g. to track a newer Pumpkin commit than what's currently published).

Prerequisites

• Rust (via rustup)
• Android NDK (installed via Android Studio's SDK Manager, or standalone)
• cargo-ndk: cargo install cargo-ndk
• Android SDK Platform Tools (for adb, if installing via command line)
• The Rust targets for all three architectures:

  rustup target add aarch64-linux-android
  rustup target add armv7-linux-androideabi
  rustup target add x86_64-linux-android
  

Step 1 (optional): Build the native server binaries yourself

From the root of the Pumpkin source repo:

$env:ANDROID_NDK_HOME = "C:\path\to\Android\Sdk\ndk\<version>"

cargo ndk -t arm64-v8a -t armeabi-v7a -t x86_64 --platform 26 -o .\android-build build --release -p pumpkin

Note: --platform 26 targets Android API level 24+ networking symbols (e.g. getifaddrs/freeifaddrs), which some of Pumpkin's dependencies require. Without it, linking may fail with undefined symbol errors.

This produces three binaries:

target\aarch64-linux-android\release\pumpkin
target\armv7-linux-androideabi\release\pumpkin
target\x86_64-linux-android\release\pumpkin

You may see error: No cdylib file found to copy at the very end — this is a harmless quirk of cargo-ndk expecting a cdylib artifact, which Pumpkin doesn't produce (it builds a plain executable). As long as all three binaries above exist, the build succeeded.

2. Copy the binaries into the Android project

copy target\aarch64-linux-android\release\pumpkin <ANDROID_PROJECT>\app\src\main\jniLibs\arm64-v8a\libpumpkin.so
copy target\armv7-linux-androideabi\release\pumpkin <ANDROID_PROJECT>\app\src\main\jniLibs\armeabi-v7a\libpumpkin.so
copy target\x86_64-linux-android\release\pumpkin <ANDROID_PROJECT>\app\src\main\jniLibs\x86_64\libpumpkin.so

Each binary must be placed under jniLibs/<abi>/libpumpkin.so — this exact naming lets Android's package installer treat it as a native library, which is what grants it execute permission at install time.

3. Build the Android APK

From the Android project root (where gradlew/gradlew.bat live):

cd <ANDROID_PROJECT>
.\gradlew clean
.\gradlew assembleDebug

Output APK:

app\build\outputs\apk\debug\app-debug.apk

If the build fails with OutOfMemoryError

Add/update gradle.properties in the project root:

org.gradle.jvmargs=-Xmx8192m -XX:MaxDirectMemorySize=2048m -Dfile.encoding=UTF-8

Then restart the Gradle daemon so it picks up the change:

.\gradlew --stop
.\gradlew assembleDebug

4. Install on a device

With a phone connected via USB (USB debugging enabled) or an emulator running:

adb install -r app\build\outputs\apk\debug\app-debug.apk

-r reinstalls in place over any existing install — no need to manually uninstall first.

If adb isn't on your PATH, use the full path from your SDK install, e.g.:

& "C:\path\to\Android\Sdk\platform-tools\adb.exe" install -r app\build\outputs\apk\debug\app-debug.apk

Automating steps 1–2

pumpkin_auto_build.py (included in this repo) automates checking for new Pumpkin releases and rebuilding the native binaries automatically. See the comments at the top of that file for configuration. It stops short of building/installing the APK itself (steps 3–4 above), so you can review changes before deploying.