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https://github.com/fzakaria/mvn2nix
Easily package your Maven Java application with the Nix package manager.
https://github.com/fzakaria/mvn2nix
java maven nix nixpkgs
Last synced: 7 days ago
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Easily package your Maven Java application with the Nix package manager.
- Host: GitHub
- URL: https://github.com/fzakaria/mvn2nix
- Owner: fzakaria
- License: mit
- Created: 2020-07-19T22:56:12.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-07-24T00:07:14.000Z (6 months ago)
- Last Synced: 2025-01-19T12:05:54.111Z (14 days ago)
- Topics: java, maven, nix, nixpkgs
- Language: Java
- Homepage:
- Size: 200 KB
- Stars: 100
- Watchers: 9
- Forks: 34
- Open Issues: 21
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
__:warning: mvn2nix is seeking a maintainer. Please open an issue if you are interested.__
[](https://builtwithnix.org)
> Easily package your Maven Java application with the Nix package manager.
* [How to use this](#how-to-use-this)
* [Generating the Nix dependencies file](#generating-the-nix-dependencies-file)
* [Building a Maven repository](#building-a-maven-repository)
* [Sample Derivation](#sample-derivation)
* [How does it work?](#how-does-it-work)
* [Development](#development)
__:warning: mvn2nix is in active development but is ready to be used. Please pin it to a commit to avoid
any flux.__
## How to use this
```bash
# non-flake
$ nix run -f https://github.com/fzakaria/mvn2nix/archive/master.tar.gz --command mvn2nix
# flake
$ nix run github:fzakaria/mvn2nix#mvn2nix
```
If you have [cachix](https://cachix.org/) installed, you can leverage our prebuilt binary.
> cachix use fzakaria
### Generating the Nix dependencies file
In the same spirit of [bundix](https://github.com/nix-community/bundix), **mvn2nix** creates a Nix set with the
*transitive closure* of all dependencies required by the application.
```bash
# non-flake usage
$ nix run -f https://github.com/fzakaria/mvn2nix/archive/master.tar.gz \
--command mvn2nix > mvn2nix-lock.json
# flake usage
$ nix run github:fzakaria/mvn2nix#mvn2nix > mvn2nix-lock.json
$ head mvn2nix-lock.json
{
"dependencies": {
"org.junit.jupiter:junit-jupiter:jar:5.6.2": {
"layout": "org/junit/jupiter/junit-jupiter/5.6.2/junit-jupiter-5.6.2.jar",
"sha256": "dfc0d870dec4c5428a126ddaaa987bdaf8026cc27270929c9f26d52f3030ac61",
"url": "https://repo.maven.apache.org/maven2/org/junit/jupiter/junit-jupiter/5.6.2/junit-jupiter-5.6.2.jar"
},
"org.codehaus.plexus:plexus-utils:pom:3.0.15": {
"layout": "org/codehaus/plexus/plexus-utils/3.0.15/plexus-utils-3.0.15.pom",
"sha256": "b4fe0bed469e2e973c661b4b7647db374afee7bda513560e96cd780132308f0b",
"url": "https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-utils/3.0.15/plexus-utils-3.0.15.pom"
},
```
You can then use this to download all the necessary dependencies to run your application.
### Building a Maven repository
Now that you have a **nix** dependencies file; we can re-construct a Maven repository using Nix!
```nix
let mvn2nix = import (fetchTarball https://github.com/fzakaria/mvn2nix/archive/master.tar.gz) { };
in
mvn2nix.buildMavenRepositoryFromLockFile { file = ./mvn2nix-lock.json; }
```
This creates a **/nix/store** path which is a Maven repository that can be used, such as in `mvn package --offline -Dmaven.repo.local=${mavenRepository}`
```bash
$ tree /nix/store/0ylsqi62jqz5gqf0dqrz5a3hj3jrzrwx-mvn2nix-repository | head
/nix/store/0ylsqi62jqz5gqf0dqrz5a3hj3jrzrwx-mvn2nix-repository
├── com
│ └── google
│ ├── code
│ │ └── findbugs
│ │ └── jsr305
│ │ └── 3.0.2
│ │ └── jsr305-3.0.2.jar -> /nix/store/w20lb1dk730v77qis8l6sjqpljwkyql7-jsr305-3.0.2.jar
│ ├── errorprone
│ │ └── error_prone_annotations
```
### Sample Derivation
```nix
{ pkgs ? import {} }:
let
mvn2nix = import
(fetchTarball "https://github.com/fzakaria/mvn2nix/archive/master.tar.gz")
{ };
mavenRepository =
mvn2nix.buildMavenRepositoryFromLockFile { file = ./mvn2nix-lock.json; };
inherit (pkgs) lib stdenv jdk11_headless maven makeWrapper;
inherit (stdenv) mkDerivation;
in mkDerivation rec {
pname = "my-artifact";
version = "0.01";
name = "${pname}-${version}";
src = lib.cleanSource ./.;
nativeBuildInputs = [ jdk11_headless maven makeWrapper ];
buildPhase = ''
echo "Building with maven repository ${mavenRepository}"
mvn package --offline -Dmaven.repo.local=${mavenRepository}
'';
installPhase = ''
# create the bin directory
mkdir -p $out/bin
# create a symbolic link for the lib directory
ln -s ${mavenRepository} $out/lib
# copy out the JAR
# Maven already setup the classpath to use m2 repository layout
# with the prefix of lib/
cp target/${name}.jar $out/
# create a wrapper that will automatically set the classpath
# this should be the paths from the dependency derivation
makeWrapper ${jdk11_headless}/bin/java $out/bin/${pname} \
--add-flags "-jar $out/${name}.jar"
'';
}
```
### Example flake usage
```nix
# flake.nix
{
inputs = {
mvn2nix.url = "github:fzakaria/mvn2nix";
utils.url = "github:numtide/flake-utils";
};
outputs = { nixpkgs, mvn2nix, utils, ... }:
let
pkgsForSystem = system: import nixpkgs {
# ./overlay.nix contains the logic to package local repository
overlays = [ mvn2nix.overlay (import ./overlay.nix) ];
inherit system;
};
in utils.lib.eachSystem utils.lib.defaultSystems (system: rec {
legacyPackages = pkgsForSystem system;
packages = utils.lib.flattenTree {
inherit (legacyPackages) myMavenProject;
};
defaultPackage = legacyPackages.myMavenProject;
});
}
```
```nix
# overlay.nix
final: prev: {
myMavenProject = final.callPackage ./myPackage.nix { };
}
```
```nix
# myPackge.nix
{ lib, stdenv, buildMavenRepositoryFromLockFile
, makeWrapper, maven, jdk11_headless
, nix-gitignore
}:
let
mavenRepository = buildMavenRepositoryFromLockFile { file = ./mvn2nix-lock.json; };
in stdenv.mkDerivation rec {
pname = "myMavenProject";
version = "0.9.3";
name = "${pname}-${version}";
src = nix-gitignore.gitignoreSource [ "*.nix" ] ./.;
nativeBuildInputs = [ jdk11_headless maven makeWrapper ];
buildPhase = ''
echo "Building with maven repository ${mavenRepository}"
mvn package --offline -Dmaven.repo.local=${mavenRepository}
'';
installPhase = ''
# create the bin directory
mkdir -p $out/bin
# create a symbolic link for the lib directory
ln -s ${mavenRepository} $out/lib
# copy out the JAR
# Maven already setup the classpath to use m2 repository layout
# with the prefix of lib/
cp target/${name}.jar $out/
# create a wrapper that will automatically set the classpath
# this should be the paths from the dependency derivation
makeWrapper ${jdk11_headless}/bin/java $out/bin/${pname} \
--add-flags "-jar $out/${name}.jar"
'';
}
```
## How does it work?
**mvn2nix** relies on [maven-invoker](https://maven.apache.org/shared/maven-invoker/); which fires off
Maven in a separate JVM process.
Maven is executed with a temporary *ephemeral* local repository for the given goals provided (defaults to **package**).
The local repository is than traversed, and each encountered file is recorded in the dependencies list.
**mvn2nix** includes an [example](examples/mvn2nix/default.nix) output & derivation that builds itself!
## Development
If you are running *mvn2nix* from this repository, you can do so with **nix-build**
```bash
$ nix-build
./result/bin/mvn2nix > example/mvn2nix-lock.json
```
If you want to test **buildMavenRepository** you can run:
```bash
$ nix-build -A buildMavenRepositoryFromLockFile --arg file "./mvn2nix-lock.json"
```
At the moment, _mvn2nix_ is **self-bootstrapped** consuming it's own _mvn2nix-lock.json_.
If for whatever reason, the JSON format changes or you need to update the dependencies, you can run _mvn2nix-bootstrap_.
```bash
$ nix-build -A mvn2nix-bootstrap
./result/bin/mvn2nix > example/mvn2nix-lock.json
```