K8s plugin for Jenkins: Always running two separate containers inside a pod
The Jenkins kubernetes plugin will always create a JNLP slave container inside the pod that is created to perform the build. The podTemplate is where you define the other containers you need in order to perform your build.
In this case it seems you would want to add a Node container to your podTemplate. In your build you would then have the build happen inside the named Node container.
You shouldn't really care where the Pod runs. All you need to do is make sure you add a container that has the resources you need (like Node in this case). You can add as many containers as you want to a podTemplate. I have some with 10 or more containers for steps like PMD, Maven, curl, etc.
I use a Jenkinsfile with pipelines.
podTemplate(cloud: 'k8s-houston', label: 'api-hire-build', containers: [ containerTemplate(name: 'maven', image: 'maven:3-jdk-8-alpine', ttyEnabled: true, command: 'cat'), containerTemplate(name: 'pmd', image: 'stash.company.com:8443/pmd:pmd-bin-5.5.4', alwaysPullImage: false, ttyEnabled: true, command: 'cat') ], volumes: [ persistentVolumeClaim(claimName: 'jenkins-pv-claim', mountPath: '/mvn/.m2nrepo') ]){ node('api-hire-build') { stage('Maven compile') { container('maven') { sh "mvn -Dmaven.repo.local=/mvn/.m2nrepo/repository clean compile" } } stage('PMD SCA (docker)') { container('pmd') { sh 'run.sh pmd -d "$PWD"/src -f xml -reportfile "$PWD"/target/pmd.xml -failOnViolation false -rulesets java-basic,java-design,java-unusedcode -language java' sh 'run.sh pmd -d "$PWD"/src -f html -reportfile "$PWD"/target/pmdreport.html -failOnViolation false -rulesets java-basic,java-design,java-unusedcode -language java' sh 'run.sh cpd --files "$PWD"/src --minimum-tokens 100 --failOnViolation false --language java --format xml > "$PWD"/target/duplicate-code.xml' } archive 'target/duplicate-code.xml' step([$class: 'PmdPublisher', pattern: 'target/pmd.xml']) } }}
Alright so I've figured out the solution. mhang li's answer was the clue but he didn't explain it one bit.
Basically, you need to modify the official Jenkins Slave image found here and modify it to include the changes for your slave as well. Essentially, you are clubbing the JNLP and Slave containers into one and building a combined image.
The modification format will just look like this (picking up from the Dockerfile linked)
FROM jenkins/slave:3.27-1MAINTAINER Oleg Nenashev <o.v.nenashev@gmail.com>LABEL Description="This is a base image, which allows connecting Jenkins agents via JNLP protocols" Vendor="Jenkins project" Version="3.27"COPY jenkins-slave /usr/local/bin/jenkins-slave**INCLUDE CODE FOR YOUR SLAVE. Eg install node, java, whatever**ENTRYPOINT ["jenkins-slave"] # Make sure you include this file as wellNow, name the slave container jnlp (Reason - bug). So now, you will have one container that spawns which will be your JNLP + Slave. All in all, your Kubernetes Plugin Pod Template will look something like this. Notice the custom url to the docker image I have put in. Also, make sure you don't include a Command To Run unless you need one.
Done! Your builds should now run within this container and should function exactly like you programmed the Dockerfile!