Running Jenkins inside a Kubernetes-Cluster
This post is a tutorial on how to setup a Jenkins instance running on Kubernetes.
There is also a previous tutorial on how to setup a Kubernetes cluster with K3s.
Jenkins Installation #
As a very first step, a namespace is being created. All Jenkins related resources will be applied to it:
kubectl create namespace jenkins
A persistent volume claim is also required in a file called jenkins-pvc.yaml:
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: jenkins-claim
namespace: jenkins
spec:
storageClassName: local-path
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
This is applied with:
kubectl create -f jenkins-pvc.yaml -n jenkins
The deployment has to be added to a the file jenkins-deployment.yaml:
apiVersion: apps/v1
kind: Deployment
metadata:
name: jenkins-deployment
spec:
replicas: 1
selector:
matchLabels:
app: jenkins
template:
metadata:
labels:
app: jenkins
spec:
containers:
- name: jenkins
image: jenkins/jenkins:lts
ports:
- name: http-port
containerPort: 8080
- name: jnlp-port
containerPort: 50000
volumeMounts:
- name: jenkins-vol
mountPath: /var/jenkins_vol
volumes:
- name: jenkins-vol
persistentVolumeClaim:
claimName: jenkins-claim
The deployment is applied with:
kubectl create -f jenkins-deployment.yaml -n jenkins
Now, there should be one pod running the Jenkins instance. This can be checked with:
kubectl get pods -n jenkins
In a file jenkins-service.yaml two service will be added, one for the Jenkins instance itself and another one for JNLP which is needed for the agent nodes:
apiVersion: v1
kind: Service
metadata:
name: jenkins
spec:
type: NodePort
ports:
- port: 8080
targetPort: 8080
nodePort: 30000
selector:
app: jenkins
---
apiVersion: v1
kind: Service
metadata:
name: jenkins-jnlp
spec:
type: ClusterIP
ports:
- port: 50000
targetPort: 50000
selector:
app: jenkins
Both services will be applied with:
kubectl create -f jenkins-service.yaml --namespace jenkins
Also here it is good to check if everything worked:
kubectl get services --namespace jenkins
To access the Jenkins instance the IP of the node and the post-number of the NodePort-service is needed. The nodes IP-address is:
kubectl get nodes -o wide
Then, to get the port of the NodePort-service:
kubectl get svc -n jenkins
Finally, the running Jenkins instance:
IMAGE 00-jenkins
Jenkins Configuration #
Now, that the instance is up and running it needs to run through some configuration steps.
In order to begin, the initial password needs to be retrieved. It can be found in the logs of the pod.
The name of the pod can be determined by:
kubectl get pods -n jenkins
Then, to access the logs, the following command needs to be executed:
kubectl logs -n jenkins <jenkins-pod-name>
The password that is shown in the logs needs to be copied into the browser in order to continue with the “Continue”-button.
IMAGE 01-jenkins
In the next step some plugins need to be installed by pressing “Install suggested plugins”.
IMAGE 02-jenkins
All suggested plugins are installed automatically.
IMAGE 03-jenkins
To continue as admin with the initial password, the “Skip and continue as admin”-button needs to be pressed.
IMAGE 04-jenkins
Jenkins provides the complete Jenkins URL.
Please note, that this is not the safe-route to take, but enough for this tutorial. In case this should be a permanent Jenkins instance, of course the admins password has to be changed as soon as possible.
IMAGE 05-jenkins
After pressing “Start using Jenkins”, the initial configuration is finished.
IMAGE 06-jenkins
Final note #
In case to restart all over again, everything can be removed be deleting the namespace:
kubectl delete all --all -n jenkins