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Last pushed: 2 years ago
Short Description
Plain jenkins image with kubernetes plugin built from master
Full Description


Jenkins plugin to run dynamic slaves in a Kubernetes/Docker environment.

Based on the Scaling Docker with Kubernetes article,
automates the scaling of Jenkins slaves running in Kubernetes.

The plugin creates a Kubernetes Pod for each slave started,
defined by the Docker image to run, and stops it after each build.

Slaves are launched using JNLP, so it is expected that the image connects automatically to the Jenkins master.
For that some environment variables are automatically injected:

  • JENKINS_URL: Jenkins web interface url
  • JENKINS_JNLP_URL: url for the jnlp definition of the specific slave
  • JENKINS_SECRET: the secret key for authentication

Tested with csanchez/jenkins-slave,
see the Docker image source code.

Configuration on Google Container Engine

Create a cluster

    gcloud container clusters create jenkins --num-nodes 1 --machine-type g1-small

and note the admin password and server certitifate.

Or use Google Developer Console to create a Container Engine cluster, then run

    gcloud container clusters get-credentials
    kubectl config view --raw

the last command will output kubernetes cluster configuration including API server URL, admin password and root certificate


To inspect the json messages sent back and forth to the Kubernetes API server you can configure
a new Jenkins log recorder for org.apache.http
at DEBUG level.


Run mvn clean package and copy target/kubernetes.hpi to Jenkins plugins folder.

Docker image

Docker image for Jenkins, with plugin installed.
Based on the official image.


docker run --rm --name jenkins -p 8080:8080 -p 50000:50000 -v /var/jenkins_home csanchez/jenkins-kubernetes

Testing locally

A local testing cluster with one node can be created with Docker Compose

docker-compose up

When using boot2docker or Docker Engine with a remote host, the remote Kubernetes API can be exposed
with docker-machine ssh MACHINE_NAME -- -L or boot2docker ssh -L

More info

Running in Kubernetes (Google Container Engine)

Assuming you created a Kubernetes cluster named jenkins this is how to run both Jenkins and slaves there.

Create a GCE disk named kubernetes-jenkins to store the data.

gcloud compute disks create --size 20GB kubernetes-jenkins

Creating the pods and services

kubectl create -f ./src/main/kubernetes/jenkins.yml
kubectl create -f ./src/main/kubernetes/service.yml

Connect to the ip of the network load balancer created by Kubernetes, port 80.
Get the ip (in this case with kubectl describe services/jenkins
(it may take a bit to populate)

$ kubectl describe services/jenkins
Name:           jenkins
Namespace:      default
Labels:         <none>
Selector:       name=jenkins
Type:           LoadBalancer
LoadBalancer Ingress:
Port:           http    80/TCP
NodePort:       http    30080/TCP
Port:           slave   50000/TCP
NodePort:       slave   32081/TCP
Session Affinity:   None
No events.

Configure Jenkins, adding the Kubernetes cloud under configuration, setting
Kubernetes URL to the container engine cluster endpoint or simply https://kubernetes.default.svc.cluster.local.
Under credentials, click Add and select Kubernetes Service Account,
or alternatively use the Kubernetes API username and password.

You may want to set Jenkins URL to the internal service IP, in this case,
to connect through the internal network.

Set Container Cap to a reasonable number for tests, i.e. 3.

Add an image with

  • Docker image: jenkinsci/jnlp-slave
  • Jenkins slave root directory: /home/jenkins

Now it is ready to be used.

Tearing it down

kubectl stop rc/jenkins
kubectl delete services/jenkins


docker build -t csanchez/jenkins-kubernetes .
Docker Pull Command
Source Repository