Mastering Shared Libraries in Jenkins Pipeline: Best Practices and Pitfalls

Shared Libraries exist to solve a common problem in CI/CD: the need for reusable code across multiple Jenkins pipelines. Instead of duplicating code, you can define a library once and use it wherever needed. This not only saves time but also ensures consistency across your builds.

You can define Shared Libraries in external source control repositories. They can be loaded into your existing pipelines, with the version specified as branches, tags, or commit hashes. When you use a library, it gets resolved and loaded during the compilation phase of your script, before execution begins. You can load libraries implicitly, allowing immediate access to classes or global variables, or explicitly by calling them in your script. For example, using @Library('my-shared-library') _ loads the library, while library('my-shared-library').com.mycorp.pipeline.Utils.someStaticMethod() allows you to call specific methods from it.

In production, be cautious about who has access to your SCM repository. Anyone who can push commits could potentially gain unlimited access to your Jenkins instance. It’s also worth noting that importing global variables or functions can lead to unintended static interpretations, which may not align with your customization needs. As of version 2.7 of the Pipeline: Shared Groovy Libraries plugin, there's a new option for loading non-implicit libraries, giving you more flexibility in how you manage your code.