GitLab Maven Repository

Version history

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 is 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 > Visibility, project features, 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 & Registries section on the left sidebar. Next, you must configure your project to authorize with the GitLab Maven repository.

Getting Started with Maven

This section covers 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.

Maven repositories work well with Gradle, too. Move onto getting started with Gradle if you want to setup a Gradle project.

Installing Maven

The required minimum versions are:

  • Java 11.0.5+
  • Maven 3.6+

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).

Getting started with Gradle

This section covers installing Gradle and initializing a Java project. This is a quickstart to help if you’re new to Gradle. If you’re already using Gradle and understand how to build your own packages, move onto the next section.

Installing Gradle

Installation is needed only if you want to create a new Gradle project. Follow instructions at gradle.org to download and install Gradle for your local development environment.

Verify you can use Gradle in your terminal by running:

gradle -version

If you want to use an existing Gradle project, installation is not necessary. Simply execute gradlew (on Linux) or gradlew.bat (on Windows) in the project directory instead.

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

------------------------------------------------------------
Gradle 6.0.1
------------------------------------------------------------

Build time:   2019-11-18 20:25:01 UTC
Revision:     fad121066a68c4701acd362daf4287a7c309a0f5

Kotlin:       1.3.50
Groovy:       2.5.8
Ant:          Apache Ant(TM) version 1.10.7 compiled on September 1 2019
JVM:          11.0.5 (Oracle Corporation 11.0.5+10)
OS:           Windows 10 10.0 amd64

Creating a project in Gradle

Understanding how to create a full Java project in Gradle 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:

gradle init

The output should be

Select type of project to generate:
  1: basic
  2: application
  3: library
  4: Gradle plugin
Enter selection (default: basic) [1..4]

Enter 3 to create a new Library project. The output should be:

Select implementation language:
  1: C++
  2: Groovy
  3: Java
  4: Kotlin
  5: Scala
  6: Swift

Enter 3 to create a new Java Library project. The output should be:

Select build script DSL:
  1: Groovy
  2: Kotlin
Enter selection (default: Groovy) [1..2]

Choose 1 to create a new Java Library project which is described in Groovy DSL. The output should be:

Select test framework:
  1: JUnit 4
  2: TestNG
  3: Spock
  4: JUnit Jupiter

Choose 1 to initialize the project with JUnit 4 testing libraries. The output should be:

Project name (default: test):

Enter a project name or hit enter to use the directory name as project name.

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 must be provided for authorization too. Support is available for personal access tokens, CI job tokens, and deploy tokens only. 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 when creating one, and add it to your Maven or Gradle configuration files.

Authenticating with a personal access token in Maven

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>

Authenticating with a personal access token in Gradle

Create a file ~/.gradle/gradle.properties with the following content:

gitLabPrivateToken=REPLACE_WITH_YOUR_PERSONAL_ACCESS_TOKEN

Add a repositories section to your build.gradle file:

repositories {
    maven {
        url "https://<gitlab-url>/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Private-Token'
            value = gitLabPrivateToken
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

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

Authenticating with a CI job token

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

Authenticating with a CI job token in Maven

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.

Authenticating with a CI job token in Gradle

To authenticate with a CI job token, add a repositories section to your build.gradle file:

repositories {
    maven {
        url "https://<gitlab-url>/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Job-Token'
            value = System.getenv("CI_JOB_TOKEN")
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

Authenticating with a deploy token

To authenticate with a deploy token, set the scope to api when creating one, and add it to your Maven or Gradle configuration files.

Authenticating with a deploy token in Maven

Add a corresponding section to your settings.xml file:

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

Authenticating with a deploy token in Gradle

To authenticate with a deploy token, add a repositories section to your build.gradle file:

repositories {
    maven {
        url "https://<gitlab-url>/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Deploy-Token'
            value = '<deploy-token>'
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

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 must 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 in Maven:

<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 corresponding section in Gradle would look like this:

repositories {
    maven {
        url "https://gitlab.com/api/v4/projects/PROJECT_ID/packages/maven"
        name "GitLab"
    }
}

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

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 are 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 does 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 serves 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>

For Gradle, the corresponding repositories section would look like:

repositories {
    maven {
        url "https://gitlab.com/api/v4/groups/GROUP_ID/-/packages/maven"
        name "GitLab"
    }
}

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

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 are available for download.

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

Project Package Instance level endpoint available
foo/bar foo/bar/1.0-SNAPSHOT Yes
gitlab-org/gitlab foo/bar/1.0-SNAPSHOT No
gitlab-org/gitlab gitlab-org/gitlab/1.0-SNAPSHOT Yes

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 corresponding repositories section in Gradle would look like:

repositories {
    maven {
        url "https://gitlab.com/api/v4/packages/maven"
        name "GitLab"
    }
}

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.

Upload using Maven

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

Upload using Gradle

Add the Gradle plugin maven-publish to the plugins section:

plugins {
    id 'java'
    id 'maven-publish'
}

Add a publishing section:

publishing {
    publications {
        library(MavenPublication) {
            from components.java
        }
    }
    repositories {
        maven {
            url "https://gitlab.com/api/v4/projects/<PROJECT_ID>/packages/maven"
            credentials(HttpHeaderCredentials) {
                name = "Private-Token"
                value = gitLabPrivateToken // the variable resides in ~/.gradle/gradle.properties
            }
            authentication {
                header(HttpHeaderAuthentication)
            }
        }
    }
}

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

Run the publish task:

gradle publish

You can then navigate to your project’s Packages & Registries 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 to install a package.

Install using Maven 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 using Maven 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.

Install using Gradle

Add a dependency to build.gradle in the dependencies section:

dependencies {
    implementation 'com.mycompany.mydepartment:my-project:1.0-SNAPSHOT'
}

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.

Creating Maven packages with GitLab CI/CD using Maven

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 serves 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:3.6-jdk-11
      script:
        - 'mvn deploy -s ci_settings.xml'
      only:
        - master
    
  4. Push those files to your repository.

The next time the deploy job runs, it copies 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 uses the configured CI environment variables.

Creating Maven packages with GitLab CI/CD using Gradle

The example below shows how to create a new package each time the master branch is updated:

  1. Make sure you use the Job-Token authentication as described in “Authenticating with a CI job token in Gradle”.

  2. Add a deploy job to your .gitlab-ci.yml file:

    deploy:
      image: gradle:6.5-jdk11
      script:
        - 'gradle publish'
      only:
        - master
    
  3. Push those files to your repository.

Version validation

The version string is validated using the following regex.

\A(\.?[\w\+-]+\.?)+\z

You can play around with the regex and try your version strings on this regular expression editor.

Troubleshooting

Review network trace logs

If you are having issues with the Maven Repository, you may want to review network trace logs.

For example, try to run mvn deploy locally with a PAT token and use these options:

mvn deploy \
-Dorg.slf4j.simpleLogger.log.org.apache.maven.wagon.providers.http.httpclient=trace \
-Dorg.slf4j.simpleLogger.log.org.apache.maven.wagon.providers.http.httpclient.wire=trace
Caution: When you set these options, all network requests are logged and a large amount of output is generated.

Useful Maven command-line options

There are some Maven command-line options that may be useful when performing 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'