How to configure a Jenkins 2 Pipeline so that Jenkinsfile uses a predefined variable

Question

I have several projects that use a Jenkinsfile which is practically the same. The only difference is the git project that it has to checkout. This forces me to have one Jenk

Answer 1

You can use the Pipeline Shared Groovy Library plugin to have a library that all your projects share in a git repository. In the documentation you can read about it in detail.

If you have a lot of Pipelines that are mostly similar, the global variable mechanism provides a handy tool to build a higher-level DSL that captures the similarity. For example, all Jenkins plugins are built and tested in the same way, so we might write a step named buildPlugin:

// vars/buildPlugin.groovy
def call(body) {
    // evaluate the body block, and collect configuration into the object
    def config = [:]
    body.resolveStrategy = Closure.DELEGATE_FIRST
    body.delegate = config
    body()

    // now build, based on the configuration provided
    node {
        git url: "https://github.com/jenkinsci/${config.name}-plugin.git"
        sh "mvn install"
        mail to: "...", subject: "${config.name} plugin build", body: "..."
    }
}

Assuming the script has either been loaded as a Global Shared Library or as a Folder-level Shared Library the resulting Jenkinsfile will be dramatically simpler:

Jenkinsfile (Scripted Pipeline)

buildPlugin {
    name = 'git'
}

The example shows how a jenkinsfile passes name = git to the library. I currently use a similar setup and am very happy with it.