Jenkins Custom WAR Packager

Custom WAR Packager (CWP) allows building ready-to-fly Jenkins packages using a YAML specification. The tool can produce Docker images, WAR files, and Jenkinsfile Runner docker images (aka single-shot Jenkins masters). These bundles may include Jenkins core, plugins, extra libraries, and self-configuration via Groovy Hook Scripts or Configuration-as-Code Plugin YAML files.

See this blog post for more information.

Demo

• Jenkins WAR - all latest - bundles master branches for core and some key libraries/modules
• Jenkins WAR - all latest with Maven - same as a above, but with Maven
• External Task Logging to Elasticsearch - runs External Logging demo and preconfigures it using System Groovy Hooks. The demo is packaged with Docker, and it provides a ready-to-fly Docker Compose package.
• Configuration as Code - configuring WAR with Configuration-as-Code Plugin via YAML
• Core components build - demonstrates how to modify core components (libraries, modules)
• Custom WAR Packager CI Demo - Standalone demo with an integrated CI flow
• Jenkinsfile Runner - Packaging of Docker image for Jenkinsfile Runner
• Custom Jenkins distribution formula for the Chinese users - Build your own Jenkins automatically

Usage

The tool offers a CLI interface and a Maven Plugin wrapper.

CLI

You can find the binary file from here. For the CLI use case, you should pick up a jar file with dependencies.

java -jar custom-war-packager-cli.jar -configPath=mywar.yml -version=1.0-SNAPSHOT -tmpDir=tmp

After the build the generated WAR file will be put to tmp/output/target/${artifactId}.war.

To run the tool in a demo mode with this config, use the following command:

java -jar war-packager-cli.jar -demo

Invoke the tool without options to get a full CLI options list.

Maven

Maven plugin runs the packager and generates the artifact. The artifact will be put to "target/custom-war-packager-maven-plugin/output/target/${bundle.artifactId}.war" and added to the project artifacts.

  <build>
    <plugins>
      <plugin>
        <groupId>io.jenkins.tools.custom-war-packager</groupId>
        <artifactId>custom-war-packager-maven-plugin</artifactId>
        <version>@[email protected]</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>custom-war</goal>
            </goals>
            <configuration>
              <configFilePath>spotcheck.yml</configFilePath>
              <warVersion>1.1-SNAPSHOT</warVersion>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

Note that this plugin invokes Maven-in-Maven, and that it won't pass build options to the plugin. Configuration file can be used to configure the downstream builder.

Prerequisites

• Maven 3.5.0 or above
• Java 8
• Git (if any Git sources are defined)

Custom WAR Packager offers a Docker Image which bundles all the required tools.

Configuration file

Example:

bundle:
  groupId: "io.github.oleg-nenashev"
  artifactId: "mywar"
  description: "Just a WAR auto-generation-sample"
  vendor: "Jenkins project"
buildSettings:
  docker:
    base: "jenkins/jenkins:2.121.1"
    tag: "jenkins/demo-external-task-logging-elk"
    build: true
war:
  groupId: "org.jenkins-ci.main"
  artifactId: "jenkins-war"
  source:
    version: 2.107
plugins:
  - groupId: "org.jenkins-ci.plugins"
    artifactId: "matrix-project"
    source:
      version: 1.9
  - groupId: "org.jenkins-ci.plugins"
    artifactId: "durable-task"
    source:
      git: https://github.com/jglick/durable-task-plugin.git
      branch: watch-JENKINS-38381
  - groupId: "org.jenkins-ci.plugins.workflow"
    artifactId: "workflow-durable-task-step"
    source:
      git: https://github.com/jglick/workflow-durable-task-step-plugin.git
      commit: 6c424e059bba90fc94a9c1e87dc9c4a324bfef26
  - groupId: "io.jenkins"
    artifactId: "configuration-as-code"
    source:
      version: 0.11-alpha-rc373.933033f6b51e
libPatches:
  - groupId: "org.jenkins-ci.main"
    artifactId: "remoting"
    source:
      git: https://github.com/jenkinsci/remoting.git
systemProperties: {
     jenkins.model.Jenkins.slaveAgentPort: "50000",
     jenkins.model.Jenkins.slaveAgentPortEnforce: "true"}
groovyHooks:
  - type: "init"
    id: "initScripts"
    source: 
      dir: scripts
casc:
  - id: "jcasc-config"
    source:
      dir: jenkins.yml

There are more options available. See the linked demos and the automated tests for examples.

Please note that given to the build workspace being defaulted to "/build", the Jenkinsfile-runner version used must be at least 1.0-beta-7.

Build multi-platform images

Docker Buildx provides the ability to build a multi-platform image.

Simply you can follow three steps to build a multi-platform image:

1. Enable CLI experimental features of you docker daemon.
2. Create a appropriate driver via docker buildx create --use.
3. Set it in the YAML config file. Basically, you need to add buildx and platform.

Example:

buildSettings:
  docker:
    base: "jenkins/jenkins:2.121.1"
    tag: "jenkins/demo-external-task-logging-elk"
    platform: linux/amd64,linux/arm64
    output: push
    buildx: true
    build: true

BOM support

The plugin supports Bill of Materials (BOM), described in JEP-309, as an input.

If BOM is defined, Custom WAR Packager will load plugin and component dependencies from there. In case we want BOM to specify the core version, the bomIncludeWar flag must be set to true. The example below takes the input from BOM and produces custom WAR and Docker packages.

bundle:
  groupId: "io.jenkins.tools.war-packager.demo"
  artifactId: "bom-demo"
buildSettings:
  bom: bom.yml
  bomIncludeWar: true
  environment: aws
  docker:
    base: "jenkins/jenkins:2.121.2"
    tag: "jenkins/cwp-bom-demo"
    build: true

An example of such configuration is available here.

Plugins from POM

In order to simplify packaging for development versions, it is possible to link Custom War Packager to the POM file so that it takes plugins to be bundled from there.

If the pom option is set, all dependencies will be added, including test ones. The current parent will be also bundled unless the pomIgnoreRoot flag is set.

bundle:
  groupId: "io.jenkins.tools.war-packager.demo"
  artifactId: "pom-input-demo"
buildSettings:
  pom: pom.xml
  pomIgnoreRoot: true
  pomIncludeWar: true
war:
  groupId: "org.jenkins-ci.main"
  artifactId: "jenkins-war"
  source:
    version: 2.121.1

In the same way as BOM does, we can specify the core version from the pom file. If the global flag pomIncludeWar is true and the pom sets the jenkins-war.version, the jenkins.version property or it contains a dependency on org.jenkins-ci.main:jenkins-core or org.jenkins-ci.main:jenkins-war the war section in yml file will be omitted. Consequently, if the flag is set to true and the pom file does not configure the core, then the build fails.

Example is available here.

Plugin information providers

Custom WAR packager uses plugin information caching for some cases, e.g. for deciding whether a dependency is a plugin in pom.xml inputs. Right now there are 2 supported information sources: a Jenkins Update Center and a Maven repo.

Update Center Information provider

The mode was introduced in Custom WAR Packager 2.0.0, and this is a default mode in the tool.

• Plugin information is retrieved from Jenkins update centers
• Default update center: http://updates.jenkins.io/update-center.json
• Custom update center URL can be set using the updateCenterUrl flag in buildSettings
• Advanced configurations (e.g. proxy configuration) are not available for this mode at the moment

Maven Repo Information provider

Information is retrieved from Maven repositories, and hence it allows installing unreleased or blacklisted plugins which are not available through update centers. pomUseMavenPluginInfoProvider: true in buildSettings can be set to enable this mode.

• The mode caches information about plugins in the Maven repo
• The mode is not reliable when used outside clean build environments, because false positive and false negative decisions may be cached in the case of infrastructure issues
• This mode is not recommended for most of the cases. Use at your own risk.

buildSettings:
  pom: pom.xml
  pomUseMavenPluginInfoProvider: true
  pomIgnoreRoot: true

Before Custom WAR Packager 2.0.0, this provider was used by default. Builds using this version may need an update if they rely on custom update centers or unreleased/blacklisted plugins.

Advanced features

Features:

• Rebuilding Jenkins core with custom dependencies (e.g., Remoting or Stapler)
• Adding extra libraries to the Jenkins core so that they can be used in extensions

Limitations

Currently, the tool is in the alpha state. It has some serious limitations:

• All built artifacts with Git source are being installed to the local repository
  • Versions are unique for every commit, so beware of local repo pollution
• System properties work only for a custom jenkins.util.SystemProperties class defined in the core
  • Use Groovy Hook Scripts if you need to set up other system properties
• libPatches steps bundles only a specified JAR file, but not its dependencies Dependencies need to be explicitly packaged as well if they change compared to the base WAR file
  • libExcludes can be used to remove dependencies which are not required anymore