Maven is a build automation and project management tool primarily used for Java projects that helps developers manage dependencies, build processes, and documentation in a centralized way. It follows a convention-over-configuration approach by providing a standard project structure and build lifecycle, allowing teams to quickly begin development without extensive configuration.
Depot Cache provides a remote cache service that can be used with Maven, allowing you to incrementally cache and reuse parts of your builds. This cache is accessible from anywhere, both on your local machine and on CI/CD systems.
Depot Cache can be used with Maven from Depot's managed GitHub Actions runners, your local machine, or any CI/CD system.
Depot GitHub Actions runners are pre-configured to use Depot Cache with Maven - each runner is launched with a settings.xml file that is pre-populated with the connection details for Depot Cache. You must verify that remote caching is enabled via the Maven Build Cache extension in .mvn/maven-build-cache-config.xml:
<cache xmlns="http://maven.apache.org/BUILD-CACHE-CONFIG/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/BUILD-CACHE-CONFIG/1.0.0 https://maven.apache.org/xsd/build-cache-config-1.0.0.xsd">
<configuration>
<enabled>true</enabled>
<hashAlgorithm>SHA-256</hashAlgorithm>
<validateXml>true</validateXml>
<remote enabled="true" saveToRemote="true" id="depot-cache">
<url>https://cache.depot.dev</url>
</remote>
<projectVersioning adjustMetaInf="true" />
</configuration>
</cache>It is important to note that the id of your remote cache must be set to depot-cache for the Depot Cache service to work correctly in Depot GitHub Actions Runners. The cache will not be used if you use a different ID.
You should also verify that you have registered the Build Cache extension in your pom.xml file:
<build>
<extensions>
<extension>
<groupId>org.apache.maven.extensions</groupId>
<artifactId>maven-build-cache-extension</artifactId>
<version>1.0.1</version>
</extension>
</extensions>
</build>If this automatic configuration is incompatible with your specific setup, you can disable automatic configuration in your organization settings page and manually configure Maven to use Depot Cache, as described below.
To manually configure Maven to use Depot Cache, you will need to configure remote caching in your ~/.m2/settings.xml file. Configure Maven to use the Depot Cache service endpoints and set your API token where there is the DEPOT_TOKEN below:
settings.xml:
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 https://maven.apache.org/xsd/settings-1.0.0.xsd">
<servers>
<server>
<id>depot-cache</id>
<configuration>
<httpHeaders>
<property>
<name>Authorization</name>
<value>Bearer DEPOT_TOKEN</value>
</property>
</httpHeaders>
</configuration>
</server>
</servers>
</settings>Note: Maven support currently only supports Depot Organization API tokens, not user tokens.
Once Maven is configured to use Depot Cache, you can run your builds as usual. Maven will automatically communicate with Depot Cache to fetch and reuse any stored build artifacts from your previous builds.
depot/build-push-actionWhen using depot/build-push-action to build Docker images that contain Maven projects, your build needs access to Maven's remote cache credentials to benefit from caching.
These credentials are not automatically available inside your Docker build environment. Unlike builds running directly on Depot-managed GitHub Actions runners (which have automatic access to Depot Cache environment variables), containerized builds execute in isolated VMs that require explicit configuration.
Follow these steps to securely pass your Maven credentials into your Docker build:
Store the Depot token in a GitHub Secret named DEPOT_TOKEN.
Configure Maven Build Cache extension in .mvn/maven-build-cache-config.xml:
<cache xmlns="http://maven.apache.org/BUILD-CACHE-CONFIG/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/BUILD-CACHE-CONFIG/1.0.0 https://maven.apache.org/xsd/build-cache-config-1.0.0.xsd">
<configuration>
<enabled>true</enabled>
<hashAlgorithm>SHA-256</hashAlgorithm>
<validateXml>true</validateXml>
<remote enabled="true" saveToRemote="true" id="depot-cache">
<url>https://cache.depot.dev</url>
</remote>
<projectVersioning adjustMetaInf="true" />
</configuration>
</cache>settings.xml to read the Depot token from an environment variable. Create or update .m2/settings.xml:<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 https://maven.apache.org/xsd/settings-1.0.0.xsd">
<servers>
<server>
<id>depot-cache</id>
<configuration>
<httpHeaders>
<property>
<name>Authorization</name>
<value>Bearer ${env.DEPOT_TOKEN}</value>
</property>
</httpHeaders>
</configuration>
</server>
</servers>
</settings>- name: Build and push
uses: depot/build-push-action@v1
with:
context: .
file: ./Dockerfile
push: true
tags: your-image:tag
secrets: |
"DEPOT_TOKEN=${{ secrets.DEPOT_TOKEN }}"# syntax=docker/dockerfile:1
# ... other Dockerfile instructions
# Copy Maven configuration files
COPY .mvn/maven-build-cache-config.xml .mvn/maven-build-cache-config.xml
COPY .m2/settings.xml /root/.m2/settings.xml
# Run build with mounted secret
RUN --mount=type=secret,id=DEPOT_TOKEN,env=DEPOT_TOKEN \
mvn clean installAdding # syntax=docker/dockerfile:1 as the first line of your Dockerfile enables mounting secrets as environment variables.