i2pplus

Building I2P+ for Developers

This document is for developers building, hacking on, or packaging I2P+. End users looking to install I2P+ should see INSTALL.md instead.

Two build systems

I2P+ ships with two build sub-systems, both maintained side by side:

System	Primary use
Ant	The release path: components, installers, updaters, packaging, signing, jbigi
Gradle	Per-module development builds, IDE import, test tooling

Both write their output outside the workspace: ${java.io.tmpdir}/build-i2p (the build.root convention), mirroring each other. Final artifacts land in ./dist.

The Ant build is authoritative for releases; the Gradle build exists for convenience and does not produce installers.

Prerequisites

Requirement	Details
Java SDK	8 or higher to compile (class files target 1.8)
Apache Ant	1.9.8 or higher
GNU gettext	`xgettext`, `msgfmt`, and `msgmerge` must be on your PATH
Locale	Build environment must use a UTF-8 locale
JDK 14+	Only for jpackage targets (see below); pin LTS 21 via `jpackage.home`

Java 17 will become the minimum after the Jetty 12 migration.

For JVM compatibility details, see https://i2pplus.github.io/i2pplus

The JDK split

Compilation targets Java 8 bytecode; ant itself may run on any newer JDK.
jpackage (JDK 14+) must run on a separate, newer JDK. The default is /usr/lib/jvm/java-21-openjdk-amd64; override in override.properties:
```
jpackage.home=/path/to/jdk21
```
jpackage cannot cross-compile: jpackage-win must run on a Windows host.

Optional tooling

MinGW — only for buildJbigi-win64 (Windows DLLs).
fakeroot / dpkg-deb — only for buildDeb.
launch4j — bundled; used by installerexe (IzPack4 Windows wrapper).

Configuration

build.properties — build settings; release.number, i2p.build.number.
override.properties — machine-local overrides (JDK paths, keys); never commit machine-specific values.
ant help prints the full curated target list with outputs; the sections below are the highlights.

Ant build

Components

Target	Output
`build`	All `.jar` and `.war` components
`buildCore`	`./build/i2p.jar`
`buildRouter`	`./build/router.jar`
`buildRouterConsole`, `buildWEB`	Console webapp jars/wars
`buildJetty`	Jetty-related jars
`buildJbigi`	Native jbigi libs (Win64 + Linux64 + ARM64) → `installer/lib/jbigi/`
`buildAddressbook`, `buildI2PSnark`, `buildI2PTunnel`, `buildSAM`, `buildStreaming`, `buildSusiMail`, `buildSusiDNS`, `buildDesktopGui`, `buildI2PControl`, `buildImagegen`, `buildJrobin`, `buildMinistreaming`, `buildPack200`	Per-app jars/wars

Installers

Target	Output
`pkg`	`distclean` then everything: updater + installer
`installer` / `installer5`	Cross-platform IzPack GUI installer → `dist/i2pinstall_<ver>.jar`, wrapped `dist/i2pinstall.exe`
`installer-windows` / `installer5-windows`	Windows GUI installer → `dist/i2pinstall_<ver>_windows.exe`
`installer-osx`	macOS installer → `dist/i2pinstall_<ver>_osx.tar.bz2`
`installer-linux` / `installer5-linux`, `installer-freebsd`, `installer-nowindows`	Platform GUI installers
`jpackage-win`	Self-contained Windows exe (bundled runtime, JDK 14+, must run on Windows) → `dist/i2pinstaller-<ver>.exe`
`7zip-`, `zip-`	Non-installer platform archives → `dist/`

Updaters

Target	Output
`updater`	`dist/i2pupdate.zip`
`updaterWithJetty`, `updaterWithGeoIP`, `updaterWithASN`, `updaterWithJbigi`, `updaterSmall`, `updaterCompact`, …	Updater variants
`signed-updater200*`	Signed `.su3` updates → `dist/i2pupdate.su3`

Utilities & distribution

Target	Purpose
`test`, `junit.test`	Unit tests
`distclean`	Remove all derived/temporary files
`buildProperties`, `buildRequirements`	Show build configuration and requirements
`tarball`	Clean-install tar → `dist/i2p.tar.bz2`
`buildDeb`	Self-contained Debian package → `dist/i2p*.deb`
`buildAppImage`	Linux AppImage → `dist/I2P+_<ver>.appimage`
`git-tag`	Create annotated release tag
`javadoc`, `javadoc-zip`, `devdocs`, `devdocs-zip`	Documentation
`poupdate-source`	Update translation `.po` files

Gradle build

The Gradle build mirrors the ant module layout; each module has its own build.gradle:

core/  router/  installer/  apps/{ministreaming,streaming,i2ptunnel,jetty,i2psnark,systray,sam,routerconsole,desktopgui,jrobin,pack200,addressbook,susidns,susimail,i2pcontrol,imagegen}

Typical workflow (from the repo root):

./gradlew tasks                # list tasks
./gradlew :core:build          # build the core module
./gradlew :router:build        # build the router module
./gradlew codeCoverageReport   # Jacoco aggregate report

Gradle build output goes to ${java.io.tmpdir}/build-i2p/gradle/<module> so the workspace stays clean (matching the ant convention).

Build output verbosity

The default ant output is verbose. A custom logger can be installed once to condense it:

ant install-buildtools

This installs ConciseLogger into ~/.ant/lib and activates it via ~/.antrc (ANT_ARGS="-logger net.i2p.router.build.ConciseLogger").

Native crypto libraries (jbigi)

jbigi provides hardware-optimised modular exponentiation via GMP. Pre-built binaries for common architectures are included in the installer. To rebuild for a specific CPU, see core/c/jbigi/README.md or use ant buildJbigi.

Cross-references

INSTALL.md — end-user installation, running, and services
HACKING.md — code conventions and workflow
DIRECTORIES.md — repository layout