Dockerfile for k8s jenkins-agent

Features

• Run as root
• Ready for kubectl client:
  • A jenkins-agent service account for dev namespace will be mounted as volume on runtime by jenkins k8s pod template.
• Ready for docker client:
  • A docker credential local-docker-registry-secret for private registry will be mounted as volume at /root/docker-secret/.dockerconfigjson on runtime by jenkins k8s pod template.
  • And entrypoint.sh will copy it to proper path and will login to private registry.
  • Caveat: The agent container dangerously mounts host's /var/run/docker.sock rather than a socket toward self hosted docker engine for the performance's sake.

Contribute

• Update Dockerfile and run make
• Start building for any test project
• Run blocking command like sleep 100000 in any stage of Jenkinsfile would be helpful to debug the agent container.

Jenkins kubernetes plugin configuration

Unlisted fields can be empty. Visit https://deploy.k8s.strix.kr for latest configuration.

# Cloud-Kubernetes
Name                    kubernetes
Kubernetes Namespace    default
Jenkins URL             http://jenkins.default:8080
Jenkins tunnel          jenkins-agent.default:50000
Images
    Name                jenkins-agent
    Namespace           dev
    Labels              jenkins
    Containers	
        Name                    jnlp
        Docker image	        registry.k8s.strix.kr/jenkins-agent:latest
        Always pull image       (checked)
        Working directory       /root
        Command to run          (empty)
        Arguments ..	        ${computer.jnlpmac} ${computer.name}
        Allocate pseudo-TTY     (checked)
    Volumes	
        Host Path Volume
            Host path           /var/run/docker.sock
            Mount path	        /var/run/docker.sock
        Secret Volume
            Secret name	        local-docker-registry-secret
            Mount path	        /root/docker-secret
    ...
    	
 	Service Account	    jenkins-agent
        

Solve DinD volume mounting problem

Current agent image mounts docker host's (k8s node) /var/run/docker.sock, So volume mounting needs tricky pattern.

For example, below command will not mount SCM tree's ./src dir but k8s node's $PWD/src dir.

docker run -v ./src:/my-images-some-directory my-image do-something

To solve this problem, ./entrypoint.sh exports the variable $DOCKER_HOST_HOME which is real host path of jenkins agent's $HOME (/root). So, This can be use when mounting volume in DinD situation.

For example, below command will work!

docker -run -v ${PWD/$HOME/$DOCKER_HOST_HOME}/src:/my-images-some-directory my-image do-something