Jenkins pipeline and Docker multi-stage builds howto - docker

Question

Question
I have to configure CI/CD for number of Git repositories with help of Jenkins (and DockerHub as CD target). I did that with help of Docker multi-stage build (see Considerations). I'm afraid to misunderstand/overcomplicate a simple idea.
Is Jenkins + Docker multi-stage build = best/good practice? Am I applying the idea in the correct way?
Considerations
From this presentation I assume using Docker inside Jenkins is a good idea. After reading an article Using Multi-Stage Builds to Simplify and Standardize Build Processes, Docker multi-stage builds looks to be the next step of using Jenkins + Docker.
Answers to similar question also say Docker multi-stage makes sense, but doesn't provide an example of realisation.
Implementation
Jenkins creates pipeline from SCM repository.
Git repository
Dockerfile
Jenkinsfile
project-folder
|-src
|-pom.xml
Dockerfile
FROM alpine as source
RUN apk --update --no-cache add git
COPY project-folder repo
FROM maven:3.6.3-jdk-8 as test
COPY --from=source repo repo
WORKDIR repo
RUN mvn clean test
FROM maven:3.6.3-jdk-8 as build
COPY --from=test repo repo
WORKDIR repo
RUN mvn clean package
FROM openjdk:8 as final
MAINTEINER xxx <xxx#gmail.com>
LABEL owner="xxx"
COPY --from=build repo/target/some-lib-1.8.jar /usr/local/some-lib.jar
ENTRYPOINT ["java", "-jar", "/usr/local/some-lib.jar"]
Jenkinsfile
I used docker build --target for more granularity on Jenkins UI.
#!/usr/bin/env groovy
def imageId = "use-name/image-name:1.$BUILD_NUMBER"
pipeline {
agent {
label 'docker' # separate agent (launched as JAR on host machine) to avoid running docker inside docker
}
stages {
stage('Test') {
steps {
script {
sh "docker build --no-cache --target test -t ${imageId} ."
}
}
}
stage('Build') {
steps {
script {
sh "docker build --target build -t ${imageId} ."
}
}
}
stage('Image') {
steps {
script {
sh "docker build --target final -t ${imageId} ."
}
}
}
stage('Deploy') {
steps {
script {
docker.withRegistry('' , 'dockerhub') {
dockerImage = docker.build("${imageId}")
dockerImage.push()
}
}
}
}
stage('Clean') {
steps{
sh "docker rmi ${imageId}"
}
}
}
}

Answer 1

following taleodor's answer I would suggest next jenkinsfile:
pipeline {
agent {
label 'docker' # separate agent (launched as JAR on host machine) to avoid running docker inside docker
}
environment {
imageId = 'use-name/image-name:1.$BUILD_NUMBER'
docker_registry = 'your_docker_registry'
docker_creds = credentials('your_docker_registry_creds')
}
stages {
stage('Docker build') {
steps {
sh "docker build --no-cache --force-rm -t ${imageId} ."
}
}
stage('Docker push') {
steps {
sh'''
docker login $docker_registry --username $docker_creds_USR --password $docker_creds_PSW
docker push $imageId
docker logout
'''
}
}
stage('Clean') {
steps{
sh "docker rmi ${imageId}"
}
}
}
}