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Maven packages in the Package Repository

Publish Maven artifacts in your project’s Package Registry. Then, install the packages whenever you need to use them as a dependency.

Build a Maven package

This section explains how to install Maven and build a package.

If you already use Maven and know how to build your own packages, go to the next section.

Maven repositories work well with Gradle, too. To set up a Gradle project, see get started with Gradle.

Install 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. After installation is complete, verify you can use Maven in your terminal by running:

mvn --version

The output should be similar to:

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"

Create a project

Follow these steps to create a Maven project that can be published to the GitLab Package Registry.

  1. Open your terminal and create a directory to store the project.

  2. From the new directory, run this 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:

    • DgroupId: A unique string that identifies your package. 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).

This message indicates that the project was set up successfully:

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

In the folder where you ran the command, a new directory should be displayed. The directory name should match the DartifactId parameter, which in this case, is my-project.

Build a Java project with Gradle

This section explains how to install Gradle and initialize a Java project.

If you already use Gradle and know how to build your own packages, go to the next section.

Install Gradle

If you want to create a new Gradle project, you must install Gradle. Follow instructions at gradle.org to download and install Gradle for your local development environment.

In your terminal, verify you can use Gradle by running:

gradle -version

To use an existing Gradle project, in the project directory, on Linux execute gradlew, or on Windows execute gradlew.bat.

The output should be similar to:

------------------------------------------------------------
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

Create a Java project

Follow these steps to create a Maven project that can be published to the GitLab Package Registry.

  1. Open your terminal and create a directory to store the project.

  2. From this new directory, run this 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]

  3. 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

  4. 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]

  5. Enter 1 to create a new Java Library project that is described in Groovy DSL. The output should be:

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

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

    Project name (default: test):

  7. Enter a project name or press Enter to use the directory name as project name.

Authenticate to the Package Registry with Maven

To authenticate to the Package Registry, you need either a personal access token or deploy token.

Authenticate with a personal access token in Maven

To use a personal access token, add this section to your settings.xml file.

The name must be Private-Token.

<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>

Authenticate with a deploy token in Maven

To use a deploy token, add this section to your settings.xml file.

The name must be Deploy-Token.

<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>

Authenticate with a CI job token in Maven

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

The name must be Job-Token.

<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>

Read more about how to create Maven packages using GitLab CI/CD.

Authenticate to the Package Registry with Gradle

To authenticate to the Package Registry, you need either a personal access token or deploy token.

Authenticate 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.example.com/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Private-Token'
            value = gitLabPrivateToken
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

Authenticate 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.example.com/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Deploy-Token'
            value = '<deploy-token>'
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

Authenticate 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.example.com/api/v4/groups/<group>/-/packages/maven"
        name "GitLab"
        credentials(HttpHeaderCredentials) {
            name = 'Job-Token'
            value = System.getenv("CI_JOB_TOKEN")
        }
        authentication {
            header(HttpHeaderAuthentication)
        }
    }
}

Use the GitLab endpoint for Maven packages

To use the GitLab endpoint for Maven packages, choose an option:

  • Project-level: Use when you have few Maven packages and they are not in the same GitLab group.
  • Group-level: Use when you have many Maven packages in the same GitLab group.
  • Instance-level: Use when you have many Maven packages in different GitLab groups or in their own namespace.

The option you choose determines the settings you add to your pom.xml file.

In all cases, to publish a package, you need:

  • A project-specific URL in the distributionManagement section.
  • A repository and distributionManagement section.

Project-level Maven endpoint

The relevant repository section of your pom.xml in Maven should look like this:

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

The corresponding section in Gradle would be:

repositories {
    maven {
        url "https://gitlab.example.com/api/v4/projects/PROJECT_ID/packages/maven"
        name "GitLab"
    }
}
  • The id is what you defined in settings.xml.
  • The PROJECT_ID is your project ID, which you can view on your project's home page.
  • Replace gitlab.example.com with your domain name.
  • For retrieving artifacts, use either the URL-encoded path of the project (like group%2Fproject) or the project's ID (like 42). However, only the project's ID can be used for publishing.

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 the 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, so you have more flexibility in naming, compared to the instance-level endpoint. However, GitLab does not guarantee the uniqueness of 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.

This example shows the relevant repository section of your pom.xml file. You still need a project-specific URL for publishing a package in the distributionManagement section:

<repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.com/api/v4/groups/GROUP_ID/-/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.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.example.com/api/v4/groups/GROUP_ID/-/packages/maven"
        name "GitLab"
    }
}
  • For the id, use what you defined in settings.xml.
  • For my-group, use your group name.
  • For PROJECT_ID, use your project ID, which you can view on your project's home page.
  • Replace gitlab.example.com with your domain name.
  • For retrieving artifacts, use either the URL-encoded path of the group (like group%2Fsubgroup) or the group's ID (like 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. All packages you have access to are available for download.

Only packages that have the same path as the project are exposed by 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

This example shows how relevant repository section of your pom.xml. You still need a project-specific URL in the distributionManagement section.

<repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.com/api/v4/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.com/api/v4/projects/PROJECT_ID/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>https://gitlab.example.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.example.com/api/v4/packages/maven"
        name "GitLab"
    }
}
  • The id is what you defined in settings.xml.
  • The PROJECT_ID is your project ID, which you can view on your project's home page.
  • Replace gitlab.example.com with your domain name.
  • For retrieving artifacts, use either the URL-encoded path of the project (like group%2Fproject) or the project's ID (like 42). However, only the project's ID can be used for publishing.

Publish a package

After you have set up the remote and authentication and configured your project, publish a Maven artifact from your project.

Publish by using Maven

To publish a package by using Maven:

mvn deploy

If the deploy is successful, the build success message should be displayed:

...
[INFO] BUILD SUCCESS
...

The message should also show that the package was published to the correct location:

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

Publish by using Gradle

To publish a package by using Gradle:

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

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

  2. Add a publishing section:

    publishing {
    publications {
        library(MavenPublication) {
            from components.java
        }
    }
    repositories {
        maven {
            url "https://gitlab.example.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)
            }
        }
    }
}

  3. Replace PROJECT_ID with your project ID, which can be found on your project's home page.

  4. Run the publish task:

    gradle publish

Now navigate to your project's Packages & Registries page and view the published artifacts.

Install a package

To install a package from the GitLab Package Registry, you must configure the remote and authenticate. When this is completed, there are two ways to install a package.

Use Maven with mvn install

To install a package by using mvn install:

  1. Add the dependency manually to your project pom.xml file. To add the example created earlier, the XML would be:

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

  2. In your project, run the following:

    mvn install

The message should show that the package is downloading from the Package Registry:

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

Use Maven with mvn dependency:get

You can install packages by using the Maven commands directly.

  1. In your project directory, run:

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

The message should show that the package is downloading from the Package Registry:

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

NOTE: In the GitLab UI, on the Package Registry page for Maven, you can view and copy these commands.

Use Gradle

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

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

Remove a package

For your project, go to Packages & Registries > Package Registry.

To remove a package, click the red trash icon or, from the package details, the Delete button.

Create Maven packages with GitLab CI/CD

After you have configured your repository to use the Package Repository for Maven, you can configure GitLab CI/CD to build new packages automatically.

Create Maven packages with GitLab CI/CD by using Maven

You can 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.

  2. Add the server section with the same ID you defined in your pom.xml file. For example, use gitlab-maven as the ID:

    <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>

  3. Make sure your pom.xml file includes the following. You can either let Maven use the CI environment variables, as shown in this example, or you can hard code your server's hostname and project's ID.

    <repositories>
  <repository>
    <id>gitlab-maven</id>
    <url>${env.CI_SERVER_URL}/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
  </repository>
</repositories>
<distributionManagement>
  <repository>
    <id>gitlab-maven</id>
    <url>${env.CI_SERVER_URL}/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
  </repository>
  <snapshotRepository>
    <id>gitlab-maven</id>
    <url>${env.CI_SERVER_URL}/api/v4/projects/${env.CI_PROJECT_ID}/packages/maven</url>
  </snapshotRepository>
</distributionManagement>

  4. 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

  5. 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 example:

  • The user is root, because the job runs in a Docker container.
  • Maven uses the configured CI environment variables.

Create Maven packages with GitLab CI/CD by using Gradle

You can create a package each time the master branch is updated.

  1. Authenticate 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. Commit files to your repository.

When the pipeline is successful, the package is created.

Version validation

The version string is validated by 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

WARNING: 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 you can use 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.xml 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'

Verify your Maven settings

If you encounter issues within CI/CD that relate to the settings.xml file, try adding 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'