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Building from Source

This guide covers building Mycel from source code for developers.

Requirements

System Requirements

Requirement Version
JDK 17 (required)
Android SDK API 36 (compile)
Gradle 8.x (wrapper included)
  • IDE: Android Studio Ladybug or newer
  • OS: macOS, Linux, or Windows with WSL

Build Configuration

SDK Versions

Configuration Value
compileSdk 36
minSdk 26 (Android 8.0)
targetSdk 34 (Android 14)

Key Dependencies

Dependency Version
Kotlin 2.1.0
Android Gradle Plugin 8.10.0
Hilt 2.57.2
Room 2.8.3
Compose BOM 2024.06.00

Getting the Source

git clone https://github.com/ethene/mycel.git
cd mycel

Building

Set Java 17

Ensure JDK 17 is available:

# macOS with Homebrew
brew install openjdk@17
export JAVA_HOME=$(/usr/libexec/java_home -v 17)

# Verify
java -version
# Should show: openjdk version "17.x.x"

Debug Build

./gradlew assembleDebug

The APK will be at: app/build/outputs/apk/debug/app-debug.apk

Release Build

Release builds require signing configuration. Create app/signing.properties:

storeFile=path/to/keystore.jks
storePassword=your_password
keyAlias=your_alias
keyPassword=your_key_password

Then build:

./gradlew assembleRelease

Installing

Using ADB

adb install app/build/outputs/apk/debug/app-debug.apk

Using Build Script

The project includes a build-and-install script:

./tools/build/rebuild_install_run_autodetect.sh

This script: 1. Detects connected devices 2. Builds the debug APK 3. Installs on all devices 4. Starts the app 5. Sets up port forwarding for debugging

Module Structure

mycel/
├── app/                    # Main application module
├── core/
│   ├── dtn/               # DTN protocol, bundles
│   ├── nearby/            # Nearby Connections transport
│   ├── ble/               # BLE transport
│   ├── transport/         # Transport abstraction
│   └── capabilities/      # Device feature detection
├── feature/
│   └── ui/                # Jetpack Compose UI
└── tools/                 # Development utilities

Testing

Unit Tests

# All tests
./gradlew test

# Specific module
./gradlew :core:nearby:test
./gradlew :core:dtn:test

Instrumented Tests

./gradlew connectedAndroidTest

Development Tools

Developer Bridge

The app includes a JSON-RPC bridge for debugging. After installation:

# Set up port forwarding
adb forward tcp:8875 tcp:8765

# Check status
curl -X POST -H 'Content-Type: application/json' \
  -d '{"method":"mesh.service.status"}' \
  http://localhost:8875/

meshctl CLI

The meshctl tool provides command-line access to the bridge:

./tools/bridge/meshctl.py --serial DEVICE_SERIAL status
./tools/bridge/meshctl.py --serial DEVICE_SERIAL nearby diag

Common Issues

"JDK 17 required"

Set JAVA_HOME to a JDK 17 installation:

export JAVA_HOME=/path/to/jdk17

"SDK not found"

Ensure ANDROID_HOME or ANDROID_SDK_ROOT is set:

export ANDROID_HOME=~/Android/Sdk

Gradle Daemon Issues

Clear the Gradle cache if builds fail unexpectedly:

./gradlew --stop
rm -rf ~/.gradle/caches/

Version Management

The app version is controlled by a single file:

app/src/main/assets/version.txt

The build system reads this file and generates: - versionName for display - versionCode for Play Store (if ever published)

Release Process

Releases are managed via GitHub:

  1. Update version.txt
  2. Run ./tools/release/prepare_release.sh
  3. CI builds and publishes the APK to GitHub Releases

Contributing

  1. Fork the repository
  2. Create a feature branch
  3. Make changes
  4. Run tests: ./gradlew test
  5. Submit a pull request

See also: Architecture Overview | Message Flow