GitLab Maven Repository

With the GitLab Maven Repository, every project can have its own space to store its Maven artifacts.

GitLab Maven Repository

Enabling the Maven Repository

Note: This option is available only if your GitLab administrator has enabled support for the Maven repository.

After the Packages feature is enabled, the Maven Repository will be available for all new projects by default. To enable it for existing projects, or if you want to disable it:

  1. Navigate to your project’s Settings > General > Permissions.
  2. Find the Packages feature and enable or disable it.
  3. Click on Save changes for the changes to take effect.

You should then be able to see the Packages section on the left sidebar. Next, you must configure your project to authorize with the GitLab Maven repository.

Getting Started

This section will cover installing Maven and building a package. This is a quickstart to help if you’re new to building Maven packages. If you’re already using Maven and understand how to build your own packages, move onto the next section.

Installing Maven

Follow the instructions at maven.apache.org to download and install Maven for your local development environment. Once installation is complete, verify you can use Maven in your terminal by running:

mvn --version

You should see something similar to the below printed in the output:

Apache Maven 3.6.1 (d66c9c0b3152b2e69ee9bac180bb8fcc8e6af555; 2019-04-04T20:00:29+01:00)
Maven home: /Users/<your_user>/apache-maven-3.6.1
Java version: 12.0.2, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk-12.0.2.jdk/Contents/Home
Default locale: en_GB, platform encoding: UTF-8
OS name: "mac os x", version: "10.15.2", arch: "x86_64", family: "mac"

Creating a project

Understanding how to create a full Java project is outside the scope of this guide but you can follow the steps below to create a new project that can be published to the GitLab Package Registry.

Start by opening your terminal and creating a directory where you would like to store the project in your environment. From inside the directory, you can run the following Maven command to initialize a new package:

mvn archetype:generate -DgroupId=com.mycompany.mydepartment -DartifactId=my-project -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

The arguments are as follows:

  • DgroupId: A unique string that identifies your package. You should follow the Maven naming conventions.
  • DartifactId: The name of the JAR, appended to the end of the DgroupId.
  • DarchetypeArtifactId: The archetype used to create the initial structure of the project.
  • DinteractiveMode: Create the project using batch mode (optional).

After running the command, you should see the following message, indicating that your project has been set up successfully:

...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.429 s
[INFO] Finished at: 2020-01-28T11:47:04Z
[INFO] ------------------------------------------------------------------------

You should see a new directory where you ran this command matching your DartifactId parameter (in this case it should be my-project).

Adding the GitLab Package Registry as a Maven remote

The next step is to add the GitLab Package Registry as a Maven remote. If a project is private or you want to upload Maven artifacts to GitLab, credentials will need to be provided for authorization too. Support is available for personal access tokens and CI job tokens only. Deploy tokens and regular username/password credentials do not work.

Authenticating with a personal access token

To authenticate with a personal access token, set the scope to api and add a corresponding section to your settings.xml file:

<settings>
  <servers>
    <server>
      <id>gitlab-maven</id>
      <configuration>
        <httpHeaders>
          <property>
            <name>Private-Token</name>
            <value>REPLACE_WITH_YOUR_PERSONAL_ACCESS_TOKEN</value>
          </property>
        </httpHeaders>
      </configuration>
    </server>
  </servers>
</settings>

You should now be able to upload Maven artifacts to your project.

Authenticating with a CI job token

If you’re using Maven with GitLab CI/CD, a CI job token can be used instead of a personal access token.

To authenticate with a CI job token, add a corresponding section to your settings.xml file:

<settings>
  <servers>
    <server>
      <id>gitlab-maven</id>
      <configuration>
        <httpHeaders>
          <property>
            <name>Job-Token</name>
            <value>${env.CI_JOB_TOKEN}</value>
          </property>
        </httpHeaders>
      </configuration>
    </server>
  </servers>
</settings>

You can read more on how to create Maven packages using GitLab CI/CD.

Configuring your project to use the GitLab Maven repository URL

To download and upload packages from GitLab, you need a repository and distributionManagement section in your pom.xml file. If you’re following the steps from above, then you’ll need to add the following information to your my-project/pom.xml file.

Depending on your workflow and the amount of Maven packages you have, there are 3 ways you can configure your project to use the GitLab endpoint for Maven packages:

  • Project level: Useful when you have few Maven packages which are not under the same GitLab group.
  • Group level: Useful when you have many Maven packages under the same GitLab group.
  • Instance level: Useful when you have many Maven packages under different GitLab groups or on their own namespace.
Note: In all cases, you need a project specific URL for uploading a package in the distributionManagement section.

Project level Maven endpoint

The example below shows how the relevant repository section of your pom.xml would look like:

<repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </snapshotRepository>
</distributionManagement>

The id must be the same with what you defined in settings.xml.

Replace PROJECT_ID with your project ID which can be found on the home page of your project.

If you have a self-managed GitLab installation, replace gitlab.com with your domain name.

Note: For retrieving artifacts, you can use either the URL encoded path of the project (e.g., group%2Fproject) or the project’s ID (e.g., 42). However, only the project’s ID can be used for uploading.

Group level Maven endpoint

Introduced in GitLab Premium 11.7.

If you rely on many packages, it might be inefficient to include the repository section with a unique URL for each package. Instead, you can use the group level endpoint for all your Maven packages stored within one GitLab group. Only packages you have access to will be available for download.

The group level endpoint works with any package names, which means the you have the flexibility of naming compared to instance level endpoint. However, GitLab will not guarantee the uniqueness of the package names within the group. You can have two projects with the same package name and package version. As a result, GitLab will serve whichever one is more recent.

The example below shows how the relevant repository section of your pom.xml would look like. You still need a project specific URL for uploading a package in the distributionManagement section:

<repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/groups/GROUP_ID/-/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </snapshotRepository>
</distributionManagement>

The id must be the same with what you defined in settings.xml.

Replace my-group with your group name and PROJECT_ID with your project ID which can be found on the home page of your project.

If you have a self-managed GitLab installation, replace gitlab.com with your domain name.

Note: For retrieving artifacts, you can use either the URL encoded path of the group (e.g., group%2Fsubgroup) or the group’s ID (e.g., 12).

Instance level Maven endpoint

Introduced in GitLab Premium 11.7.

If you rely on many packages, it might be inefficient to include the repository section with a unique URL for each package. Instead, you can use the instance level endpoint for all maven packages stored in GitLab and the packages you have access to will be available for download.

Note that only packages that have the same path as the project are exposed via the instance level endpoint.

ProjectPackageInstance level endpoint available
foo/barfoo/bar/1.0-SNAPSHOTYes
gitlab-org/gitlabfoo/bar/1.0-SNAPSHOTNo
gitlab-org/gitlabgitlab-org/gitlab/1.0-SNAPSHOTYes

The example below shows how the relevant repository section of your pom.xml would look like. You still need a project specific URL for uploading a package in the distributionManagement section:

<repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </snapshotRepository>
</distributionManagement>

The id must be the same with what you defined in settings.xml.

Replace PROJECT_ID with your project ID which can be found on the home page of your project.

If you have a self-managed GitLab installation, replace gitlab.com with your domain name.

Note: For retrieving artifacts, you can use either the URL encoded path of the project (e.g., group%2Fproject) or the project’s ID (e.g., 42). However, only the project’s ID can be used for uploading.

Uploading packages

Once you have set up the remote and authentication and configured your project, test to upload a Maven artifact from a project of yours:

mvn deploy

If the deploy is successful, you should see the build success message again:

...
[INFO] BUILD SUCCESS
...

You should also see that the upload was uploaded to the correct registry:

Uploading to gitlab-maven: https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven/com/mycompany/mydepartment/my-project/1.0-SNAPSHOT/my-project-1.0-20200128.120857-1.jar

You can then navigate to your project’s Packages page and see the uploaded artifacts or even delete them.

Installing a package

Installing a package from the GitLab Package Registry requires that you set up the remote and authentication as above. Once this is completed, there are two ways for installaing a package.

Install with mvn install

Add the dependency manually to your project pom.xml file. To add the example created above, the XML would look like:

<dependency>
  <groupId>com.mycompany.mydepartment</groupId>
  <artifactId>my-project</artifactId>
  <version>1.0-SNAPSHOT</version>
</dependency>

Then, inside your project, run the following:

mvn install

Provided everything is set up correctly, you should see the dependency downloaded from the GitLab Package Registry:

Downloading from gitlab-maven: http://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven/com/mycompany/mydepartment/my-project/1.0-SNAPSHOT/my-project-1.0-20200128.120857-1.pom

Install with mvn dependency:get

The second way to install packages is to use the Maven commands directly. Inside your project directory, run:

mvn dependency:get -Dartifact=com.nickkipling.app:nick-test-app:1.1-SNAPSHOT

You should see the same downloading message confirming that the project was retrieved from the GitLab Package Registry.

Tip: Both the XML block and Maven command are readily copy and pastable from the Package details page, allowing for quick and easy installation.

Removing a package

In the packages view of your project page, you can delete packages by clicking the red trash icons or by clicking the Delete button on the package details page.

Creating Maven packages with GitLab CI/CD

Once you have your repository configured to use the GitLab Maven Repository, you can configure GitLab CI/CD to build new packages automatically. The example below shows how to create a new package each time the master branch is updated:

  1. Create a ci_settings.xml file that will serve as Maven’s settings.xml file. Add the server section with the same id you defined in your pom.xml file. For example, in our case it’s gitlab-maven:

    <settings xmlns="http://maven.apache.org/SETTINGS/1.1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.1.0 http://maven.apache.org/xsd/settings-1.1.0.xsd">
      <servers>
        <server>
          <id>gitlab-maven</id>
          <configuration>
            <httpHeaders>
              <property>
                <name>Job-Token</name>
                <value>${env.CI_JOB_TOKEN}</value>
              </property>
            </httpHeaders>
          </configuration>
        </server>
      </servers>
    </settings>
    
  2. Make sure your pom.xml file includes the following:

    <repositories>
      <repository>
        <id>gitlab-maven</id>
        <url>https://gitlab.com/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
      </repository>
    </repositories>
    <distributionManagement>
      <repository>
        <id>gitlab-maven</id>
        <url>https://gitlab.com/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
      </repository>
      <snapshotRepository>
        <id>gitlab-maven</id>
        <url>https://gitlab.com/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
      </snapshotRepository>
    </distributionManagement>
    
    Tip: You can either let Maven utilize the CI environment variables or hardcode your project’s ID.
  3. Add a deploy job to your .gitlab-ci.yml file:

    deploy:
      image: maven:3.3.9-jdk-8
      script:
        - 'mvn deploy -s ci_settings.xml'
      only:
        - master
    
  4. Push those files to your repository.

The next time the deploy job runs, it will copy ci_settings.xml to the user’s home location (in this case the user is root since it runs in a Docker container), and Maven will utilize the configured CI environment variables.

Troubleshooting

Useful Maven command line options

There’s some maven command line options which maybe useful when doing tasks with GitLab CI/CD.

  • File transfer progress can make the CI logs hard to read. Option -ntp,--no-transfer-progress was added in 3.6.1. Alternatively, look at -B,--batch-mode or lower level logging changes.

  • Specify where to find the POM file (-f,--file):

     package:
       script:
         - 'mvn --no-transfer-progress -f helloworld/pom.xml package'
    
  • Specify where to find the user settings (-s,--settings) instead of the default location. There’s also a -gs,--global-settings option:

     package:
       script:
         - 'mvn -s settings/ci.xml package'
    

Verifying your Maven settings

If you encounter issues within CI that relate to the settings.xml file, it might be useful to add an additional script task or job to verify the effective settings.

The help plugin can also provide system properties, including environment variables:

mvn-settings:
  script:
    - 'mvn help:effective-settings'

package:
  script:
    - 'mvn help:system'
    - 'mvn package'