Configure Maven to use Depot Cache

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 works 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.

Note: You need a Depot API token to authenticate with the cache service. Maven support currently only supports Depot Organization API tokens, not user tokens.

Local workstation

Configure 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>

Then configure Maven to use the Depot Cache service in your ~/.m2/settings.xml file. Replace DEPOT_TOKEN with your API token:

<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>

After you configure Maven to use Depot Cache, run your builds as usual. Maven automatically communicates with Depot Cache to fetch and reuse any stored build artifacts from your previous builds.

Local workstation with containerized builds

When building Docker images that contain Maven projects locally, your build needs access to Maven's remote cache credentials to benefit from caching. Containerized builds execute in isolated environments that require explicit configuration.

Maven configuration

Configure 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>

Create or update .m2/settings.xml to read the Depot token from an environment variable:

<?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>

Dockerfile configuration

Update your Dockerfile to copy configuration files and mount the secret:

# 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 install

Adding # syntax=docker/dockerfile:1 as the first line of your Dockerfile enables mounting secrets as environment variables.

Depot CLI

depot build --secret id=DEPOT_TOKEN,env=DEPOT_TOKEN -t your-image:tag .

Docker buildx

docker buildx build --secret id=DEPOT_TOKEN,env=DEPOT_TOKEN -t your-image:tag .

Bake

Define the secret in your docker-bake.hcl file:

target "default" {
  context    = "."
  dockerfile = "Dockerfile"
  tags       = ["your-image:tag"]
  secret = [
    {
      type = "env"
      id   = "DEPOT_TOKEN"
    }
  ]
}

Then run the build:

DEPOT_TOKEN=your_token depot bake

Depot GitHub Actions runners

Depot GitHub Actions runners are pre-configured to use Depot Cache with Maven. Each runner launches with a settings.xml file pre-populated with the connection details for Depot Cache.

You must configure 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>

Set the id of your remote cache to depot-cache for the Depot Cache service to work correctly in Depot GitHub Actions Runners.

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>

Then run your Maven builds as normal:

jobs:
  build:
    runs-on: depot-ubuntu-24.04
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-java@v4
        with:
          distribution: 'temurin'
          java-version: '17'
      - run: mvn clean install

To disable automatic configuration, turn off Allow Actions jobs to automatically connect to Depot Cache in your organization settings page. You can then manually configure Maven as described in the Local workstation section.

Depot GitHub Actions runners with containerized builds

When running containerized builds on Depot GitHub Actions runners, your build needs access to Maven's remote cache credentials. These credentials aren't automatically available inside your Docker build environment.

Maven configuration

Configure 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>

Create or update .m2/settings.xml to read the Depot token from an environment variable:

<?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>

Dockerfile configuration

Update your Dockerfile to copy configuration files and run the build with mounted secret:

# 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 install

Adding # syntax=docker/dockerfile:1 as the first line of your Dockerfile enables mounting secrets as environment variables.

`depot/build-push-action`

Store the Depot token in a GitHub Secret named DEPOT_TOKEN, then configure your workflow:

- 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 }}"

`depot/bake-action`

Define the secret in your docker-bake.hcl file:

target "default" {
  context    = "."
  dockerfile = "Dockerfile"
  tags       = ["your-image:tag"]
  secret = [
    {
      type = "env"
      id   = "DEPOT_TOKEN"
    }
  ]
}

Then configure your workflow:

- name: Bake
  uses: depot/bake-action@v1
  with:
    files: docker-bake.hcl
  env:
    DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}

Docker CLI

Store the Depot token in a GitHub Secret named DEPOT_TOKEN, then configure your workflow:

- name: Build
  run: |
    docker buildx build \
      --secret id=DEPOT_TOKEN,env=DEPOT_TOKEN \
      -t your-image:tag .
  env:
    DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}