Interview › Scripting (Bash, Groovy)
What is a Jenkins shared library, and how is it written in Groovy? [Advanced]
Answer
A Jenkins shared library is reusable Pipeline code stored in a separate repository or configured library. It is written in Groovy using vars/ for global pipeline steps and src/ for classes, allowing teams to standardize CI/CD behavior across repositories.
Technical explanation
vars/myStep.groovy exposes a callable step named myStep in Jenkinsfiles.
src/ contains regular Groovy classes organized by package.
Shared libraries reduce copy-paste Jenkinsfiles and centralize patterns like Docker build, security scan, deployment, and notifications.
Hands-on example
// vars/buildAndPush.groovy
def call(Map cfg = [:]) {
sh "docker build -t ${cfg.image}:${env.BUILD_NUMBER}."
sh "docker push ${cfg.image}:${env.BUILD_NUMBER}"
}
// Jenkinsfile
@Library('platform-ci') _
buildAndPush(image: 'registry.example.com/orders-api')Preparing for an interview?
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