GitLab CI template for Maven

This project implements a GitLab CI/CD template to build, test and analyse your Maven-based projects.

Usage

In order to include this template in your project, add the following to your gitlab-ci.yml:

include:
  - project: 'to-be-continuous/maven'
    ref: '3.7.1'
    file: '/templates/gitlab-ci-maven.yml'

Global configuration

The Maven template uses some global configuration throughout all jobs.

About $MAVEN_CFG_DIR

This variable is used to define the Maven configuration directory. It is used to declare the cache policy and marked the ${MAVEN_CFG_DIR}/repository directory as cached (not to download Maven dependencies over and over again).

If you have a good reason to do differently, you'll have to override the MAVEN_CLI_OPTS variable as well as the cache policy.

About $MAVEN_SETTINGS_FILE

If a file is found at the $MAVEN_SETTINGS_FILE location, the template automatically uses it as a settings.xml (using the --settings option on command line).

Note that with this design you are free to either:

1. inline the settings.xml file into your repository source (⚠️ make sure not to inline secrets but use the ${env.MY_PASSWORD} replacement pattern instead and define the MY_PASSWORD variable as secret project variable),
2. or define the settings.xml content as a file type project variable.

Jobs

mvn-build job

The Maven template features a job mvn-build that performs build and tests at once. This stage is performed in a single job for optimization purpose (it saves time) and also for test jobs dependency reasons (some test jobs such as SONAR analysis have a dependency on test results).

It uses the following variable:

About Code Coverage

With its default arguments, the GitLab CI template for Maven forces the use of JaCoCo Maven Plugin to compute code coverage during unit tests execution.

In addition it makes the necessary to integrate code coverage stats into your GitLab project (report badge and viewable coverage in merge requests).

If yo want to fix the JaCoCo plugin version or tweak the default configuration, you may have to configure the JaCoCo Maven Plugin in your pom.xml, but be aware of the following:

• do not declare JaCoCo executions for prepare-agent and report goals as each would run twice during unit tests (not necessarily with the expected configuration). If you really need to do so anyway, you'll have to override the $MAVEN_BUILD_ARGS variable to remove the explicit invocation to JaCoCo goals.
• make sure the report goal computes a CSV report, that is used by the Maven template to compute the global coverage stat.

More info:

• Maven Surefire Plugin
• surefire:test parameters

mvn-sonar job — SonarQube analysis

This job, disabled by default, is bound to the test stage and performs a SonarQube analysis of your code. This job uses the following variables:

Recommended minimal configuration

1. set the SONAR_HOST_URL value either in your .gitlab-ci.yml file or as a project or group variable (⚠️ setting it as a group variable will enable the SonarQube analysis for all the children projects),
2. define your SonarQube credentials (🔒 SONAR_TOKEN or SONAR_LOGIN & 🔒 SONAR_PASSWORD) as project or group variables,
3. configure the project SonarQube settings in the pom.xml file (⚠️ the SonarScanner for Maven completely ignores the sonar-project.properties file):

   <properties>
     <!-- the SonarQube project key -->
     <sonar.projectKey>write-key-here</sonar.projectKey>
     <!-- additional SonarQube settings can go here -->
     ...
   </properties>

   More info about SonarQube settings

⚠️ if using SonarCloud (a cloud-based SonarQube-as-a-Service), you'll have to define the additional sonar.organization property (see mandatory-parameters).

ℹ️ As SonarCloud determined the organization and projectKey properties from the project's GitLab context when importing the project, you can reuse the predefined GitLab variables as follows in your pom.xml:

<properties>
  <!-- SonarCloud settings -->
  <sonar.organization>${env.CI_PROJECT_ROOT_NAMESPACE}</sonar.organization>
  <sonar.projectKey>${env.CI_PROJECT_ROOT_NAMESPACE}_${env.CI_PROJECT_NAME}</sonar.projectKey>
</properties>

Automatic Branch Analysis & Merge Request Analysis

This template relies on SonarScanner's GitLab integration, which is able to auto-detect whether to launch Branch Analysis or Merge Request Analysis from GitLab's environment variables.

⚠️ This feature also depends on your SonarQube server version and license. If using Community Edition, you'll have to install the sonarqube-community-branch-plugin to enable automatic Branch & Merge Request analysis (only works from SonarQube version 8).

⚠️ Merge Request Analysis only works if you're running Merge Request pipeline strategy (default).

Disable the job

ℹ️ See Usage for more information about disabling any job that MAY not be required in a project or group.

Without disabling the job, you can still exclude a particular project by defining a property <sonar.skip>true</sonar.skip> in the pom.xml of the project or module you want to exclude.

mvn-dependency-check job

This job enables a manual Dependency-Check analysis.

It is bound to the test stage, and uses the following variables:

A Dependency Check is a quite long operation and therefore the job is configured to be ran manually by default.

However, if you want to enable an automatic Dependency-Check scan, you will have to override the rules keyword for the mvn-dependency-check job.

Dependency-Check fetches its vulnerbility database from the NVD API which has rate limiting. Using an NVD API key, the rate limit is higher which reduces the execution time of Dependency-Check.

In order to configure an NVD API key you need to:

• Set the NVD_API_KEY variable with your NVD API key. ⚠️ This is a sensitive value, so we recommend you add it as a masked Gitlab variable
• Add -DnvdApiKey=$NVD_API_KEY to MAVEN_DEPENDENCY_CHECK_ARGS

In case your Gitlab runners cannot contact the NVD API (e.g. if they are not allowed to connect to the Internet), you can maintain a local data feed cache with the vulnz tool.

In order to configure Dependency-Check to fetch the vulnerabilities from your cache you need to:

• Run the vulnz tool in order to fetch the vulnerabilities and store them as data feeds (the data feeds will be stored as JSON files with the NVD Vulnerability Data API version 2.0 schema)
• Make these data feeds accessible via a URL reachable by your Gitlab runners
• Add -DnvdDatafeedUrl=https://URL-OF-LOCAL-CACHE to MAVEN_DEPENDENCY_CHECK_ARGS

Furthermore, if you want to upload Dependency-Check reports to SonarQube, you have to:

• Move mvn-dependency-check to the build stage
• Add -Dformats=html,json,xml to MAVEN_DEPENDENCY_CHECK_ARGS to output reports
  • HTML report to read the report on SonarQube UI
  • JSON report to create SonarQube issues from the report
  • XML report to import into DefectDojo security dashboard
• Add -Dsonar.dependencyCheck.htmlReportPath and -Dsonar.dependencyCheck.jsonReportPath with the paths of the generated html and json reports to SonarQube arguments.

More info:

• Maven Dependency-Check Plugin

mvn-no-snapshot-deps job

This job checks if the project has release-only dependencies, i.e., no _*-SNAPSHOT_ versions, using the Maven Enforcer plugin.

Failure is allowed in feature branches.

It is bound to the test stage, and uses the following variables:

mvn-sbom job

This job generates a SBOM file listing all dependencies using cyclonedx-maven-plugin.

It is bound to the test stage, and uses the following variables:

mvn-release & mvn-deploy-* jobs

These jobs are disabled by default and - when enabled - respectively perform the following:

1. a Maven release:prepare of your current branch
   • only triggers the first part of the release (version changes in pom.xml, Git commits and version tag)
   • provides a default integration with semantic-release (see below)
   • the second part of the release (package and publish to a Maven registry) is performed by the mvn-deploy job below
2. a Maven deploy of your Java packages (jar, war, etc.) to any Maven-compliant registry
   • mvn-deploy-release publishes the stable version on the tag pipeline triggered by a mvn-release,
   • mvn-deploy-snapshot publishes the snapshot version on other branches.

They are bound to the publish stage, and use the following variables:

More info:

• Maven Deploy Plugin
• Maven Release Plugin

Inject the Git branch slug in SNAPSHOT versions

In order to segregate your SNAPSHOT versions per branch, the Maven template allows you to add the Git branch slug into the pom version. Thus, any other project willing to use your SNAPSHOT packages will be able to do so, explicitly setting its dependency on the desired version (branch). Only the production branch (main or master by default) will be preserved from this behavior.

This feature can be enabled setting MAVEN_DEPLOY_SNAPSHOT_WITH_SLUG_ENABLED to true.

Example: for a project with <version>1.2.1-SNAPSHOT</version> in its pom.xml:

semantic-release integration

If you activate the semantic-release-info job from the semantic-release template, the mvn-release job will rely on the generated next version info.

• the release will only be performed if a semantic release is present
• the version is passed to the Maven Release plugin as the release version argument adding -DreleaseVersion=${SEMREL_INFO_NEXT_VERSION} to the MAVEN_RELEASE_ARGS value

⚠️ Both the Maven Release plugin and semantic-release template use a dedicated tag format that need to be set accordingly. By default, the Maven Release plugin uses ${artifactId}-${version} and semantic-release uses ${version} For exemple you can modify the semantic-release tag format with the SEMREL_TAG_FORMAT variable (see semantic-release template variables).

ℹ️ semantic-release determines the next release version from the existing tags in the Git repository. As the default semantic-release tag format (${version}) is not the Maven default, if leaving defaults, semantic-release will always determine the next version to release as 1.0.0, trying to keep overwriting the same version. In addition to the functional problem, this might result in a release failure as soon as trying to release version 1.0.0 for the second time (as Maven repos configured as "release" repos will not permit overwriting). Simply set SEMREL_TAG_FORMAT as shown below to have the semantic-release tag format match the maven release plugin one.

variables:
  # double dollar to prevent evaluation (escape char)
  SEMREL_TAG_FORMAT: "myArtifactId-$${version}"

Or you can override the maven release plugin tag format.

Note: It is the mvn-release job that will perform the release and so you only need the semantic-release-info job. Set the SEMREL_RELEASE_DISABLED variable as shown below.

variables:
  SEMREL_RELEASE_DISABLED: "true"

Finally, the semantic-release integration can be disabled with the MVN_SEMREL_RELEASE_DISABLED variable.

Maven repository authentication

Your Maven repository may require authentication credentials to publish artifacts.

You may handle them in the following ways:

1. define all required credentials as 🔒 project variables,
2. make sure your pom.xml (or ancestor) declares your <repository> and <snapshotRepository> with server ids in a <distributionManagement> section,
3. in your ${MAVEN_CFG_DIR}/settings.xml file, define the repository servers credentials in the <servers> section using the ${env.VARIABLE} pattern—will be automatically evaluated and replaced by Maven.

Example 1 — using the GitLab Maven Repository

pom.xml:

<!-- ... -->
<distributionManagement>
  <snapshotRepository>
      <id>gitlab-maven</id>
      <url>${env.CI_API_V4_URL}/projects/${env.CI_PROJECT_ID}/packages/maven</url>
  </snapshotRepository>
  <repository>
      <id>gitlab-maven</id>
      <url>${env.CI_API_V4_URL}/projects/${env.CI_PROJECT_ID}/packages/maven</url>
  </repository>
</distributionManagement>
<!-- ... -->

${MAVEN_SETTINGS_FILE}:

<settings>
  <servers>
    <!-- required when using GitLab's package registry to deploy -->
    <!-- see: https://docs.gitlab.com/ee/user/packages/maven_repository/index.html#use-the-gitlab-endpoint-for-maven-packages -->
    <server>
        <id>gitlab-maven</id>
        <configuration>
            <httpHeaders>
                <property>
                    <name>Job-Token</name>
                    <value>${env.CI_JOB_TOKEN}</value>
                </property>
            </httpHeaders>
        </configuration>
    </server>
  </servers>
</settings>

Example 2 — using an Artifactory repository with same credentials for snapshot & release

pom.xml:

<!--... -->
<distributionManagement>
  <snapshotRepository>
    <id>artifactory</id>
    <url>https://artifactory.acme.host/artifactory/maven-snapshot-repo</url>
  </snapshotRepository>
  <repository>
    <id>artifactory</id>
    <url>https://artifactory.acme.host/artifactory/maven-release-repo</url>
  </repository>
</distributionManagement>
<!--...-->

${MAVEN_CFG_DIR}/settings.xml:

<settings>
  <servers>
    <server>
      <id>artifactory</id>
      <username>${env.ARTIFACTORY_USER}</username>
      <password>${env.ARTIFACTORY_PASSWORD}</password>
    </server>
  </servers>
  <mirrors>
    <mirror>
      <id>artifactory.mirror</id>
      <mirrorOf>central</mirrorOf>
      <name>Artifactory Maven 2 central repository mirror</name>
      <url>https://artifactory.acme.host/artifactory/maven-virtual-repo/</url>
    </mirror>
  </mirrors>
</settings>

SCM authentication

A Maven release involves some Git push operations.

You can either use an ssh key or an authenticated and authorized Git user.

Using an SSH key

We recommend you to use a project deploy key with write access to your project.

The key should not have a passphrase (see how to generate a new SSH key pair).

Specify 🔒 $GIT_PRIVATE_KEY as protected project variable with the private part of the deploy key.

-----BEGIN 0PENSSH PRIVATE KEY-----
blablabla
-----END OPENSSH PRIVATE KEY-----

The template handles both classic variable and file variable.

⚠️ The scm connections in your pom.xml should use the ssh protocol

  <scm>
    <connection>scm:git:git@gitlab-host/path/to/my/project.git</connection>
    <developerConnection>scm:git:git@gitlab-host/path/to/my/project.git</developerConnection>
    ...
  </scm>

Using Git user authentication

Simply specify 🔒 $GIT_USERNAME and 🔒 $GIT_PASSWORD as protected project variables and they will be dynamically evaluated and appended to the Maven release arguments.

Note that the password should be an access token with write_repository scope and Maintainer role.

⚠️ The scm connections in your pom.xml should use the https protocol

  <scm>
    <connection>scm:git:https://gitlab-host/path/to/my/project.git</connection>
    <developerConnection>scm:git:https://gitlab-host/path/to/my/project.git</developerConnection>
    ...
  </scm>

Variants

Jib variant

This variant builds optimized Docker and OCI images for your Java applications (without deep mastery of Docker best-practices) with Jib.

Configuration

This variant uses the Jib Maven Plugin to build a Docker container and publish that container to a registry.

Images and registries config

The template uses GitLab registries and authentication defaults. See the Docker template for configuring alternate registries and credentials.

Security scanning and reporting

Jib build and publish configuration

Tho mvn-build job produces and uploads the container snapshot to the registry provided in $MAVEN_JIB_SNAPSHOT_IMAGE via the Jib build goal, e.g., mvn verify com.google.cloud.tools:jib-maven-plugin:build.

Publishing the release image follows the two-phase Maven release and deploy model. The mvn-release job is responsible for versioning and tagging the pom.xml using the Maven Release Plugin, e.g., release:prepare. The mvn-deploy-release job deploys, or "releases," the container via skopeo copy arguments to the provided registry in $MAVEN_JIB_RELEASE_IMAGE.

Usage

See the Jib Quickstart for minimal guidance on the use of the plugin for your project. If you're here, you probably have a use case, i.e., you kicked off a JHipster project and found Jib pre-configured for containerization.

The template uses GitLab registries and authentication defaults. See the Docker template for configuring alternate registries and credentials.

$MAVEN_JIB_BUILD_ARGS sets the snapshot container publish registry via a System Property, -Djib.to.image=$MAVEN_JIB_SNAPSHOT_IMAGE. This can be declaratively provided in the POM configuration for the Jib plugin and omitted, e.g., #MAVEN_JIB_BUILD_ARGS or $MAVEN_JIB_BUILD_ARGS: "" in the project .gitlab-ci.yml. This is advanced usage and should be understood in context of how skopeo copy works in the production pipeline.

Registry authorization

The variant tooling, Jib and Skopeo, support Docker configuration files (default). Jib supports additional authentication methods, including credential helpers, the POM and CLI, and even Maven Settings, e.g., .m2/settings.xml.

All authentication methods should use masked GitLab environment variables.

Example

include:
  # main template
  - project: 'to-be-continuous/maven'
    ref: '3.7.1'
    file: '/templates/gitlab-ci-maven.yml'
  # Jib is implemented as an extension to Maven, and uses supporting features of the TBC Maven template
  - project: 'to-be-continuous/maven'
    ref: '3.7.1'
    file: '/templates/gitlab-ci-maven-jib.yml'

variables: