How to cache data for containers

Question

I am using a maven container,I want to know if there is any method using which i can cache the data whenever the jenkins pipeline runs so that i don't have to re-download various stuff like dependencies every time the pipeline runs?

Answer 1

Many build tools like maven etc, will download external dependencies and cache them locally for future re-use. 

Since containers are initially created with "clean" file systems, this can result in slower Pipelines, as they may not take advantage of on-disk caches between subsequent Pipeline runs.

Pipeline supports adding custom arguments which are passed to Docker, allowing users to specify custom docker volumes to mount, which can be used for caching data on the agent between Pipeline runs. 

The following example will cache ~/.m2 between Pipeline runs utilizing the maven container, thereby avoiding the need to re-download dependencies for subsequent runs of the Pipeline.

Jenkinsfile (Declarative Pipeline)

pipeline {
    agent {
        docker {
            image 'maven:3-alpine'
            args '-v $HOME/.m2:/root/.m2'
        }
    }
    stages {
        stage('Build') {
            steps {
                sh 'mvn -B'
            }
        }
    }
}

In case you are using a scripted pipeline here's how you can do it:

Jenkinsfile (Scripted Pipeline)

node {
    /* Requires the Docker Pipeline plugin to be installed */
    docker.image('maven:3-alpine').inside('-v $HOME/.m2:/root/.m2') {
        stage('Build') {
            sh 'mvn -B'
        }
    }
}