Gradle Jenkins Job DSL Plugin

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This is a plugin to manage Jenkins Job DSL projects in a Gradle project.

Contents

• Usage
  • Apply Plugin
  • How does it work
  • Writing Job DSL Scripts
    • Helper Classes
    • Job Builders
    • Thirdparty Libraries
  • Generate XML
  • Upload Jobs to Jenkins
  • Configure Servers
  • Seed Job
  • Custom Configuration
  • Filter Jobs
  • Generated DSL and Job DSL extensions
• Development
  • Build the Plugin
  • Test the Plugin
  • Debugging the DSL tasks
  • Contributing
• Examples
• Hints
• Credits
• License

Usage

The plugin can be used to locally generate XML files for the jobs and to upload the generated jobs to a Jenkins instance.

Apply Plugin

To apply the plugin you need to add the necessary Maven repositories to the build script. The minimal build script looks like this:

buildscript {
    ext.jenkinsJobdslPluginVersion = '3.7.0'

    repositories {
        maven {
            url 'https://plugins.gradle.org/m2'
        }

        maven {
            url 'https://repo.jenkins-ci.org/releases/'
        }
    }

    dependencies {
        classpath("com.here.gradle.plugins:gradle-jenkins-jobdsl-plugin:${jenkinsJobdslPluginVersion}") {
            // Exclude unneeded transitive dependencies that can cause dependency resolution issues.
            exclude(module: 'bootstrap')
            exclude(module: 'groovy-all')
            exclude(module: 'org-netbeans-insane')

            // Exclude unneeded transitive dependencies on XML libraries that can break the generation of config files.
            // See: https://issues.jenkins-ci.org/browse/JENKINS-35638
            exclude(module: 'xalan')
            exclude(module: 'xercesImpl')
        }
    }
}

apply plugin: 'com.here.jobdsl'

repositories {
    maven {
        url 'https://plugins.gradle.org/m2'
    }
}

dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.4.15'

    compile("com.here.gradle.plugins:gradle-jenkins-jobdsl-plugin:${jenkinsJobdslPluginVersion}") {
        exclude(module: 'org-netbeans-insane')
        exclude(module: 'xalan')
        exclude(module: 'xercesImpl')
    }
}

How does it work

To come as close as possible to the behaviour of a normal Job DSL seed job the plugin launches a Jenkins instance in the background and executes the Job DSL scripts inside of this Jenkins. This implementation enables support for the generated DSL and Job DSL extensions as described below.

To load plugins in this Jenkins instance they have to be added as dependencies to the jenkinsPlugins configuration:

dependencies {
    // Some Job DSL features only work when plugins are installed, for example cloudbees-folder is required
    // to be able to create folders (https://jenkinsci.github.io/job-dsl-plugin/#path/folder).
    jenkinsPlugins 'org.jenkins-ci.plugins:cloudbees-folder:6.2.1'
}

Known issues with plugins:

• The org.jenkins-ci.plugins:ws-cleanup plugin has a dependency on an old version of jenkins-core. This adds some XML parser libraries to the classpath which conflict with the XML parser expected by newer Jenkins versions. As jenkins-core is provided anyway it should be excluded:

jenkinsPlugins('org.jenkins-ci.plugins:ws-cleanup:0.34') {
    exclude module: 'jenkins-core'
}

Writing Job DSL Scripts

By default all *.groovy files from src/jobdsl and its subdirectories are evaluated as Job DSL scripts. You can change the location by configuring the source set:

sourceSets {
    jobdsl {
        groovy {
            srcDirs 'myCustomSrcFolder'
        }
    }
}

Helper Classes

You can add Groovy or Java classes to the respective source directories src/main/groovy and src/main/java and use those classes in your Job DSL scripts, because they are automatically added to the classpath.

Job Builders

The recommended way to implement job templates are job builder classes. The plugin provides a basic JobBuilder class that can be extended to create templates. Below you can find an example of how to create a template that automatically enables the timestamp plugin for all jobs that use the template:

import com.here.gradle.plugins.jobdsl.util.JobBuilder
import javaposse.jobdsl.dsl.Job

class CustomJobBuilder extends JobBuilder {

    CustomJobBuilder(DslFactory dslFactory) {
        super(dslFactory)

        addDsl {
            wrappers {
                timestamps()
            }
        }
    }

}

To use the template you have to create an instance of your custom job builder class. You can add additional DSL code by passing it to the addDsl method. The builder will concatenate all closures and execute them in the order they were added when build is called. The JobBuilder provides convenience methods like addFreeStyleDsl or addMatrixdsl for each job type that optimize IDE support compared to using the generic addDsl method. You also have to set the job type by calling any of freestyleJob, matrixJob and so on. These methods optionally take a DSL closure argument for convenience.

def job = new CustomJobBuilder(
        dslFactory: this,
        name: 'MyExampleJob'
).freeStyleJob {

    description 'My example job'

    steps {
        shell('Hello World!')
    }
}

job.build()

Thirdparty Libraries

To use thirdparty libraries in your Job DSL scripts add them to the dependencies closure of the build script. For example the Job DSL plugin itself is added there to be able to use the JobBuilder class. This example shows how to add the Google Guava library:

dependencies {
    compile localGroovy()
    compile "com.here.gradle.plugins:gradle-jenkins-jobdsl-plugin:${jobDslPluginVersion}"
    compile 'com.google.guava:guava:19.0'
}

Generate XML

./gradlew dslGenerateXml

The XML files will be generated in build/jobdsl/.

Upload Jobs to Jenkins

# Upload jobs to a server without authorization
./gradlew dslUpdateJenkins --jenkinsUrl=http://localhost:8080/

# Upload jobs to a server with authorization
./gradlew dslUpdateJenkins --jenkinsUrl=http://localhost:8080/ --jenkinsUser=yourUsername --jenkinsApiToken=yourApiToken

# Do a dry run without changing any jobs
./gradlew dslUpdateJenkins --jenkinsUrl=http://localhost:8080/ --dryRun

Configure Servers

You can configure the different server you use in the build script instead of providing the configuration on the command line:

jobdsl {
    servers {
        localhost {
            jenkinsUrl = 'http://localhost:8080/'
        }

        staging {
            jenkinsUrl = 'http://your.jenkins.url:8080/'
            jenkinsUser = 'yourUsername'
            jenkinsApiToken = 'yourApiToken'
        }
    }
}

To use this configuration you have to select the server on the command line. You can override the configuration on the command line, e.g. when you don't want to put your credentials in the build script:

# Use the localhost configuration
./gradlew dslUpdateJenkins --server=localhost

# Override the user and API token from the configuration
./gradlew dslUpdateJenkins --server=staging --jenkinsUser=yourOtherUsername --jenkinsApiToken=yourOtherApiToken

If you want each team member to use their own credentials the gradle-credentials-plugin provides a nice way to let the team members store their credentials encrypted without having to put them in the build script or on the command line every time.

Seed Job

To create a seed job similar to the Job DSL seed jobs (see Using Job DSL) just create a freestyle job and run the Gradle command in a shell build step. Note that this will still use the REST API instead of the internal Jenkins API to create the jobs.

Since version 1.0.28 you can use the GroovySeedJobBuilder to create a seed job that runs in a System Groovy build step instead of using the REST API. This provides much better performance.

Custom Configuration

There are use cases where you want to change a part of your job configuration on the command line. For example you might want to create all jobs disabled on your localhost, and only enable them by default on your production Jenkins instance. For this the plugin supports a configuration map that is forwarded to the Job DSL scripts. The example below shows how to add a parameter to enable or disable all jobs:

jobdsl {
    configuration = [
        disableJobs: project.properties['disableJobs']?.toBoolean() ?: false
    ]
}

The values from the configuration map can be accessed from the Job DSL scripts by calling DslConfig.get('key'). The adapted build method of the CustomJobBuilder class looks like this:

@Override
Job build(Class<? extends Job> jobClass, @DelegatesTo(Job.class) Closure closure) {
    def job = super.build(jobClass, closure)
    job.with {
        disabled(DslConfig.get('disableJobs'))
    }
    return job
}

The configuration map is forwarded to the DSL scripts by serializing it to JSON, so only put values in it that can properly be serialized and deserialized by the JsonBuilder and JsonSlurper Groovy classes.

Now you can provide a value for the property on the command line to enable or disable your jobs. You can also provide a default value for the property in your gradle.properties file.

./gradlew -PdisableJobs=true dslGenerateXml

You can also have server specific configuration in the build.gradle file which can be accessed by calling DslConfig.get('key'):

jobdsl {
    servers {
        localhost {
            configuration: [ key: 'value' ]
        }
    }
}

Filter Jobs

To update only a part of the configured jobs the filter option can be used. It takes a regular expression as argument and only job names that match this expression are evaluated:

# Generate XML only for job names that contain "build"
./gradlew dslGenerateXml --filter=".*build.*"

# Only upload jobs from the folder "MyFolder"
# Note that /.* is put in brackets and made optional with a question mark, this makes sure that also the folder itself
# is uploaded. You could also use "^MyFolder.*", but in this case any item in the folder "MyFolder2" would also be
# uploaded.
./gradlew dslUpdateJenkins --filter="^MyFolder(/.*)?"

Generated DSL and Job DSL extensions

Job DSL has built-in support for many Jenkins plugins. Additionally there are two mechanisms that add support for plugins which are not directly supported:

1. Generated DSL: This method uses annotations to discover configuration endpoints of plugins automatically and generates a DSL for them. This works for many plugins when they use the correct annotations.
2. Job DSL Extensions: Plugins can also define their own DSL which is then available when the plugin is loaded by Jenkins.

Both mechanisms are supported by the gradle-jenkins-jobdsl-plugin. To use them the plugins have to be added to the jenkinsPlugins configuration:

dependencies {
    // This plugin defines a Job DSL extension.
    jenkinsPlugins 'org.jenkins-ci.plugins:jgiven:0.15.1'

    // This plugin is supported by the generated DSL.
    jenkinsPlugins 'org.jenkins-ci.plugins:cvs:2.13'
}

Development

Build the Plugin

To build the plugin execute:

# Only build
./gradlew plugin:assemble

# Publish to local maven repository (version will be 1.0)
./gradlew plugin:publishToMavenLocal

Test the Plugin

To run the tests of the plugin execute:

./gradlew plugin:check

Debugging the DSL tasks

To debug the tasks DslGenerateXml and DslUpdateJenkins using IntelliJ follow these steps:

1. Uncomment these two lines in AbstractDslTask:

   //'-Xdebug',
   //'-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005'

2. Create a test in GenerateXmlTest.groovy or UpdateJenkinsTest.groovy with the scenario you want to test (e.g. usage of specific plugins).
3. Set a breakpoint in the run method of AbstractTaskRunner.groovy.
4. Create a remote debug configuration in IntelliJ: Run -> Edit Configurations... -> + Remote
5. Run the test on the command line: ./gradlew plugin:functionalTest --tests "com.here.gradle.plugins.jobdsl.tasks.GenerateXmlTest.name of your test"
6. Start the remote debug configuration in IntelliJ.

Contributing

Contributions to the project are very welcome! Please be aware that you need to sign the HERE CLA if you want to contribute to the project.

Examples

The repository contains an example project that demonstrates most features of the plugin. To run it you have to deploy a build of the plugin to your local Maven repository first, as documented in "Build the Plugin" above.

Hints

Job DSL Plugin is not required

Because the gradle-jenkins-jobdsl-plugin can use the Jenkins REST API to upload jobs to Jenkins the Job DSL Plugin does not have to be installed on the Jenkins instance. This can be useful when you do not have permission to install Jenkins plugins or the plugin cannot be installed for another reason.

JobConfigHistory Plugin and seed jobs

If you use the JobConfigHistory Plugin in combination with a seed job you should configure retention for history entries in "Manage Jenkins" -> "Configure System". Otherwise you can quickly get a huge number of history entries which has a very negative impact on seed job performance and Jenkins performance in general.

Credits

The plugin was inspired by the following two projects, many thanks to their creators!

• gradle-jenkins-plugin
• job-dsl-gradle-example

License

Copyright (c) 2016-2017 HERE Europe B.V.

See the LICENSE file in the root of this project for license details.