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A Practical Guide to Kubernetes

Non-persisting State

Explore what happens when Kubernetes containers lose non persisting state during pod termination or failure. Understand how Jenkins deployment behaves without volume persistence and observe container restarts clearing application data. This lesson helps you grasp state management challenges in Kubernetes pods.

We'll cover the following...

Deploying Jenkins

This time we’ll deploy Jenkins and see what challenges we will face.

Looking into the definition

Let’s look at the jenkins.yml definition:

YAML
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: jenkins
  annotations:
    kubernetes.io/ingress.class: "nginx"
    ingress.kubernetes.io/ssl-redirect: "false"
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
  rules:
  - http:
      paths:
      - path: /jenkins
        pathType: ImplementationSpecific
        backend:
          service:
            name: jenkins
            port:
              number: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: jenkins
spec:
  selector:
    matchLabels:
      type: master
      service: jenkins
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        type: master
        service: jenkins
    spec:
      containers:
      - name: jenkins
        image: vfarcic/jenkins
        env:
        - name: JENKINS_OPTS
          value: --prefix=/jenkins
---
apiVersion: v1
kind: Service
metadata:
  name: jenkins
spec:
  ports:
  - port: 8080
  selector:
    type: master
    service: jenkins

There’s nothing special in that YAML file. It defines an Ingress with /jenkins path, a Deployment, and a Service. We won’t waste time with it. Instead, we’ll move on and create the objects.

Creating the objects

It’s ...