Kubernetes

Volumes:

apiVersion: v1
kind: Pod
metadata:
  name: my-securitycontext-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "cat /message/message.txt && sleep 3600"]
    volumeMounts:
    - name: message-volume
      mountPath: /message
  volumes:
  - name: message-volume
    hostPath:
      path: /etc/message

SecurityContext:

apiVersion: v1
kind: Pod
metadata:
  name: my-securitycontext-pod
spec:
  securityContext:
    runAsUser: 2000
    fsGroup: 3000
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "cat /message/message.txt && sleep 3600"]
    volumeMounts:
    - name: message-volume
      mountPath: /message
  volumes:
  - name: message-volume
    hostPath:
      path: /etc/message

Config Map

apiVersion: v1
kind: ConfigMap
metadata:
   name: my-config-map
data:
   myKey: myValue
   anotherKey: anotherValue

ConfigMap – Env

apiVersion: v1
kind: Pod
metadata:
  name: my-configmap-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "echo $(MY_VAR) && sleep 3600"]
    env:
    - name: MY_VAR
      valueFrom:
        configMapKeyRef:
          name: my-config-map
          key: myKey

ConfigMap – Volume mounts

apiVersion: v1
kind: Pod
metadata:
  name: my-configmap-volume-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "echo $(cat /etc/config/myKey) && sleep 3600"]
    volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: my-config-map

 

Resource Requests:

apiVersion: v1
kind: Pod
metadata:
  name: my-resource-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', 'echo Hello Kubernetes! && sleep 3600']
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"

 

Secrets:

apiVersion: v1
kind: Secret
metadata:
  name: my-secret
stringData:
  myKey: myPassword

apiVersion: v1
kind: Pod
metadata:
  name: my-secret-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "echo Hello, Kubernetes! && sleep 3600"]
    env:
    - name: MY_PASSWORD
      valueFrom:
        secretKeyRef:
          name: my-secret
          key: myKey

Liveness Probe:

apiVersion: v1
kind: Pod
metadata:
  name: my-liveness-pod
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', "echo Hello, Kubernetes! && sleep 3600"]
    livenessProbe:
      exec:
        command:
        - echo
        - testing
      initialDelaySeconds: 5
      periodSeconds: 5

Readiness Probe

apiVersion: v1
kind: Pod
metadata:
  name: my-readiness-pod
spec:
  containers:
  - name: myapp-container
    image: nginx
    readinessProbe:
      httpGet:
        path: /
        port: 80
      initialDelaySeconds: 5
      periodSeconds: 5

Deployments:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

Replicas / Rolling Updates:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rolling-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.1
        ports:
        - containerPort: 80

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rolling-deployment
spec:
  strategy:
    rollingUpdate:
      maxSurge: 3
      maxUnavailable: 2
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.1
        ports:
        - containerPort: 80

Persistent Volume:

kind: PersistentVolume
apiVersion: v1
metadata:
  name: my-pv
spec:
  storageClassName: local-storage
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"

PVC:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  storageClassName: local-storage
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 512Mi

kind: Pod
apiVersion: v1
metadata:
  name: my-pvc-pod
spec:
  containers:
  - name: busybox
    image: busybox
    command: ["/bin/sh", "-c", "while true; do sleep 3600; done"]
    volumeMounts:
    - mountPath: "/mnt/storage"
      name: my-storage
  volumes:
  - name: my-storage
    persistentVolumeClaim:
      claimName: my-pvc

Service:

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  type: ClusterIP
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 80

NetworkPolicy

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: my-network-policy
spec:
  podSelector:
    matchLabels:
      app: secure-app
  policyTypes:
  - Ingress
  - Egress
  ingress:
  - from:
    - podSelector:
        matchLabels:
          allow-access: "true"
    ports:
    - protocol: TCP
      port: 80
  egress:
  - to:
    - podSelector:
        matchLabels:
          allow-access: "true"
    ports:
    - protocol: TCP
      port: 80

Commands

kubectl exec my-configmap-volume-pod -- ls /etc/config

kubectl exec my-configmap-volume-pod -- cat /etc/config/myKey

-- Rolling Update

kubectl set image deployment/rolling-deployment nginx=nginx:1.7.9 --record

kubectl rollout history deployment/rolling-deployment

kubectl rollout history deployment/rolling-deployment --revision=2

kubectl rollout undo deployment/rolling-deployment --to-revision=1