SHELL

custom jenkins dockerfile

FROM jenkins/jenkins:2.332.2-jdk11
USER root
RUN apt-get update && apt-get install -y lsb-release
RUN curl -fsSLo /usr/share/keyrings/docker-archive-keyring.asc 
  https://download.docker.com/linux/debian/gpg
RUN echo "deb [arch=$(dpkg --print-architecture) 
  signed-by=/usr/share/keyrings/docker-archive-keyring.asc] 
  https://download.docker.com/linux/debian 
  $(lsb_release -cs) stable" > /etc/apt/sources.list.d/docker.list
RUN apt-get update && apt-get install -y docker-ce-cli
USER jenkins
RUN jenkins-plugin-cli --plugins "blueocean:1.25.3 docker-workflow:1.28"

jenkinsfile docker

pipeline {
    agent { label 'master' }
    stages {
        stage('build') {
            steps {
                script {
                    def disk_size = sh(script: "df / --output=avail | tail -1", returnStdout: true).trim() as Integer
                    println("disk_size = ${disk_size}")
                }
            }
        }
    }
}