K8s Starter

Let's start using kubernetes from some starter project. If you are familiar enough with k8s, just ignore the chapter and go on.

StatefulSets

In starter/stateful-nginx.yaml:

apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  selector:
    matchLabels:
      app: nginx # has to match .spec.template.metadata.labels
  serviceName: "nginx"
  replicas: 3 # by default is 1
  template:
    metadata:
      labels:
        app: nginx # has to match .spec.selector.matchLabels
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "csi-rbd-sc"
      resources:
        requests:
          storage: 1Gi

kubectl apply -f starter/stateful-nginx.yaml

ConfigMap Mount as Volume

A config map:

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: starter-config-map
data:
  debugFlag: 135
  keep: 3650
---
apiVersion: v1
kind: Pod
metadata:
  name: starter-config-map-as-volume
spec:
  containers:
    - name: test-container
      image: busybox
      command: [ "/bin/sh", "-c", "ls /etc/config/" ]
      volumeMounts:
      - name: starter-config-map-vol
        mountPath: /etc/config
  volumes:
    - name: starter-config-map-vol
      configMap:
        # Provide the name of the ConfigMap containing the files you want
        # to add to the container
        name: starter-config-map
  restartPolicy: Never