Github-actions: cache repo to speed up maven builds - maven-3

Question

Maven dependencies are downloaded every time my build workflow is triggered.
Travis CI provides a way to cache maven repository. Does Github actions provider similar functionality that allows to cache maven repository?

Answer 1

For completeness, this is an example of how to cache the local Maven repository on subsequent builds:
steps:
# Typical Java workflow steps
- uses: actions/checkout#v1
- name: Set up JDK 11
uses: actions/setup-java#v1
with:
java-version: 11
# Step that does that actual cache save and restore
- uses: actions/cache#v1
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
# Step that runs the tests
- name: Run tests
run: mvn test
See this page for more details.

Answer 2

As of 2021, the most up to date official answer would be
- name: Cache local Maven repository
uses: actions/cache#v2
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
taken from an official github example at https://github.com/actions/cache/blob/master/examples.md#java---maven

Answer 3

Apparently as of 10 September 2019 caching of build dependencies is not present in Github Actions. Github staff have acknowledged that this feature is necessary, and have replied that "We're working on caching packages and artifacts between workflow executions, we'll have it by mid-November [2019]."
Source: https://github.community/t5/GitHub-Actions/Caching-files-between-GitHub-Action-executions/m-p/30974/highlight/true#M630

Answer 4

Dependency caching is now available:
https://help.github.com/en/actions/automating-your-workflow-with-github-actions/caching-dependencies-to-speed-up-workflows

Answer 5

For maven you can now use setup-java to cache the dependencies. Example:
- uses: actions/setup-java#v2.3.1
name: Install Java
with:
java-version: 8
distribution: 'adopt'
cache: 'maven'
Note that there are the same with other setup-*: node, python and ruby.

Answer 6

I started to use skjolber's Maven Cache Github Action, see https://github.com/marketplace/actions/maven-cache. My first tests are quite positive. The first build downloaded the dependencies from Maven Central; the subsequent build found the dependencies in the cache.

Answer 7

For multimodule projects one could speedup builds by building only modules affected by the recent changes using https://github.com/avodonosov/hashver-maven-plugin/
This will work given the possibility to cache the local maven repository, as described in the #Rob van der Leek's answer.
mvn install the project artifacts after every build, and on the next build the hashver-maven-plugin will find artifacts of the unaffected modules and will skip them.