JGit HTTP Server + GraalVM native image

Sample project to compile JGit HTTP server, with LFS server support, to native executable using GraalVM native-image utility.

JGit is a pure Java implementation of the Git version control system, and is available as a library to be integrated into many projects. The JGit project also implements a git server for the Git HTTP protocol, in the form of a servlet.

For LFS server support, JGit provides the LFS server project which implements 2 servlets: the Batch API servlet, and the LFS servlet which supports upload/download of large objects to a separate storage in the local file system. In addition, this project implements a servlet to support the LFS File Locking API.

This project aims to produce stand-alone, platform-specific, native executable JGitHttpServer of the JGit HTTP servlet with LFS support, using embedded Jetty servlet container, and compiled by the GraalVM native-image utility.

Gradle and Maven build scripts are provided for building the project.

Build pre-requisites

The GraalVM native-image page shows how to set up GraalVM and its native-image utility for common platforms. Gluon also provides some setup details for GraalVM native-image creation.

The GraalVM native-image utility will use the configuration files in src/main/resources/META-INF/native-image folder to assist in the native-image generation.

Gradle build tasks

To build and run the Git server in standard JVM with Gradle, execute the run task with port number, path to the local git repos, and path to the local LFS storage as parameters:

gradlew run
gradlew run --args="8080 /path/to/repos /path/to/lfs/storage"

To generate native executable, run the nativeCompile task:

gradlew nativeCompile

The nativeCompile task would take a while to compile the source code and link into an executable file. The resulting JGitHttpServer file is in:

build/native-image/JGitHttpServer

(or if building on a Windows machine:

build\native-image\JGitHttpServer.exe

)

which can then be run directly (with parameters):

./build/native-image/JGitHttpServer 8080 /path/to/repos /path/to/lfs/storage

(or if building on a Windows machine:

build\native-image\JGitHttpServer.exe 8080 \path\to\repos \path\to\lfs\storage

)

Maven build tasks

To build and run the Git server in standard JVM with Maven, execute the compile and exec:exec tasks with port number, path to the local git repos, and path to the local LFS storage as parameters:

mvnw compile
mvnw exec:exec
mvnw exec:exec -Dexec.port=8080 -Dexec.base-path=/path/to/repos -Dexec.lfs-path=/path/to/lfs/storage

To generate native executable, run the package task:

mvnw package

The package task would take a while to compile the source code and link into an executable file. The resulting JGitHttpServer file is in:

target/native-image/JGitHttpServer

(or if building on a Windows machine:

target\native-image\JGitHttpServer.exe

)

which can then be run directly (with parameters):

./target/native-image/JGitHttpServer 8080 /path/to/repos /path/to/lfs/storage

(or if building on a Windows machine:

target\native-image\JGitHttpServer.exe 8080 \path\to\repos \path\to\lfs\storage

)

Compressed native executable

The resulting JGitHttpServer executable file, whether produced by Gradle or Maven build scripts, can be further reduced in size via compression using the UPX utility, as described here.

As an example, the resulting JGitHttpServer.exe native application file produced in Windows is normally 35MB in size, but is compressed to 10MB with the UPX command: upx --best JGitHttpServer.exe