Create resusable jenkins pipeline script

The Shared Libraries (docs) allows you to make your code accessible to all your pipeline scripts. You don't have to build a plugin for that and you don't have to restart Jenkins.

E.g. this is my library and this a Jenkinsfile that calls this common function.

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EDIT (Feb 2017): The library can be accessed through Jenkins' internal Git server, or deployed through other means (e.g. via Chef) to the workflow-lib/ directory within the jenkins user's home directory. (still possible, but very unhandy).

The global library can be configured through the following means:

• an @Library('github.com/...') annotation in the Jenkinsfile pointing to the URL of the shared library repo.
• configured on the folder level of Jenkins jobs.
• configured in Jenkins configuration as global library, with the advantage that the code is trusted, i.e., not subject to script security.

A mix of the first and last method would be a not explicitly loaded shared library that is then requested only using its name in the Jenkinsfile: @Library('mysharedlib').

Depending on how often you plan on reusing your code, you could also load a function (or a set of functions) as part of another pipeline.

{
  // ...your pipeline code...

  git 'http://urlToYourGit/projectContainingYourScript'
  pipeline = load 'global-functions.groovy'
  pipeline.helloworld()    // Call one of your defined function

  // ...some other pipeline code...
}

This solution might seems a little bit cumbersome compared to StephenKing's one but what I like about this solution is that my global functions are all commited to Git and anybody can easily modify them without (almost) any knowledge of Jenkins, just basics of Groovy.

In the Groovy script your are loading, make sure you add return this at the very end. This will allow you to make calls later. Otherwise when you set pipeline = load global-functions.groovy, the variable will be set to null.