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Architecture

Display Taints

kubectl describe nodes | grep -i taint

Remove Taint

kubectl taint nodes --all node-role.kubernetes.io/master

List all API objects and their APIGROUP

kubectl api-resources

Create pod using yaml file

apiVersion: v1
kind: Pod
metadata:
  name: basicpod
  labels:
    type: webserver
spec:
  containers:
  - name: webcont
    image: nginx
    ports:
    - containerPort: 80

kubectl create -f basic.yaml

Get pod info(with internal IP)

kubectl get pod -o wide

Delete pod

kubectl delete pod basicpod

Create service

apiVersion: v1
kind: Service
metadata:
  name: basicservice
spec:
  selector:
    type: webserver
  ports:
  - protocol: TCP
    port: 80

kubectl create -f basicservice.yaml

Create multicontainer pod

apiVersion: v1
kind: Pod
metadata:
  name: basicpod
  labels:
    type: webserver
spec:
  containers:
  - name: webcont
    image: nginx
    ports:
    - containerPort: 80
  - name: fdlogger
    image: fluent/fluentd

kubectl create -f basic.yaml

Create deployment (without yaml)

kubectl create deployment firstpod --image=nginx

Get pods from specified namespace

kubectl get pod -n mynamespace

Get all pods from all namespaces

kubectl get pod --all-namespaces

Get several resources at once

kubectl get deploy,rs,po,svc,ep

Build & Design

Create and scale deployment

k create deployment try1 --image=nginx
k scale deployment try1 --replicas=2

Save deployment as yaml

k get deployment try1 -o yaml > nginx.yaml

Recreate deployment from yaml

k create -f nginx.yaml

ReadinessProbe

    - image: nginx
        imagePullPolicy: Always
        name: nginx
        readinessProbe:
          periodSeconds: 5
          exec:
            command:
              - cat
              - /tmp/healthy

Liveness + Readiness probe

- name: goproxy
        image: k8s.gcr.io/goproxy:0.1
        ports:
        - containerPort: 8080
        readinessProbe:
          tcpSocket:
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 10
        livenessProbe:
          tcpSocket:
            port: 8080
          initialDelaySeconds: 15
          periodSeconds: 20

Bash into single container pod

k exec -it podName-123ad2 -- /bin/bash

Bash into multiple container pod (select nginex container)

k exec -it podName-123ad2 -c nginx -- /bin/bash

Create job from yaml

apiVersion: batch/v1
kind: Job
metadata:
  name: sleepy
spec:
  template:
    spec:
      containers:
      - name: resting
        image: busybox
        command: ["/bin/sleep"]
        args: ["3"]
      restartPolicy: Never

k create -f job.yaml

Get job info

k get job sleepy -o yaml

Create job which runs 5 times

apiVersion: batch/v1
kind: Job
metadata:
  name: sleepy
spec:
  completions: 5
  template:
    spec:
      containers:
      - name: resting
        image: busybox
        command: ["/bin/sleep"]
        args: ["3"]
      restartPolicy: Never

k create -f job.yaml

Create job which runs 10 times, and executes 2 pods in parallel

apiVersion: batch/v1
kind: Job
metadata:
  name: sleepy
spec:
  completions: 5
  parallelism: 2
  template:
    spec:
      containers:
      - name: resting
        image: busybox
        command: ["/bin/sleep"]
        args: ["3"]
      restartPolicy: Never

k create -f job.yaml

Create jobs with a deadline of 15 seconds

apiVersion: batch/v1
kind: Job
metadata:
  name: sleepy
spec:
  activeDeadlineSeconds: 15
  template:
    spec:
      containers:
      - name: resting
        image: busybox
        command: ["/bin/sleep"]
        args: ["3"]
      restartPolicy: Never

k create -f job.yaml

Create a CronJob which creates a Job every 2 minutes, and times out after 10s

apiVersion: batch/v1
kind: CronJob
metadata:
  name: sleepy
spec:
  schedule: "*/2 * * * *"
  jobTemplate:
    spec:
      activeDeadlineSeconds: 10
      template:
        spec:
          containers:
          - name: resting
            image: busybox
            command: ["/bin/sleep"]
            args: ["3"]
          restartPolicy: Never

k create -f cronjob.yaml

Get pods with label app=app1

k get pods -l app=app1

Create deployment with CPU/Memory requests/limits

k create deployment limited --image=busybox --dry-run=client -o yaml

This should output a deployment without limits/requests:

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: limited
  name: limited
spec:
  replicas: 1
  selector:
    matchLabels:
      app: limited
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: limited
    spec:
      containers:
      - image: busybox
        name: busybox
        resources: {}
status: {}

Edit and add limits/requests:

...
    spec:
      containers:
      - image: busybox
        name: busybox
        resources:
          limits:
            cpu: "1"
            memory: "1Gi"
          requests:
            cpu: "0.5"
            memory: "500Mi"
...

Execute command to init container in Pod

apiVersion: v1
kind: Pod
metadata:
  name: init-tester
  labels:
    app: inittest
spec:
  containers:
  - name: webservice
    image: nginx
  initContainers:
  - name: failed
    image: busybox
    command: [/bin/true]

k create -f init-tester.yaml

Show Custom Resource Definitions (CRD)

k get crd

Deployment Configuration

Create ConfigMap from a literalValue, from a file and from a directory of files

Preparation:

7803  echo c > primary/cyan
7809  echo m > primary/magenta
7810  echo y > primary/yellow
7811  echo k > primary/black
7812  echo "known as key" >> primary/black
7813  echo blue > favorite

kubectl create configmap colors \
  --from-literal=text=black \
  --from-file=./favorite \
  --from-file=./primary/

kubectl get configmap colors -o yaml

Use previously configured ConfigMap value in a pod, and check if value is available in the container

...
spec:
  containers:
  - image: nginx
    env:
    - name: ilike
      valueFrom:
        configMapKeyRef:
          name: colors
          key: favorite
    imagePullPolicy: Always
...

Set up environment variables in a pod, based on ConfigMap

...
spec:
  containers:
  - image: nginx
    env:
    - name: ilike
      valueFrom:
        configMapKeyRef:
          name: colors
          key: favorite
    envFrom:      
    - confingMapRef:
        name: colors
    imagePullPolicy: Always
...

kubectl exec -c nginx -it try1-1234sd -- /bin/bash -c'echo $ilike'

Create ConfigMap from YAML file

apiVersion: v1
kind: ConfigMap
metadata:
  name: fast-car
  namespace: default
data:
  car.make: Ford
  car.model: Mustang
  car.trim: Shelby

k create -f car-map.yaml

Add ConfigMap settings to Pod as a volume

...
spec:
  containers:
  - image: nginx
    volumeMounts:
    - mountPath: /etc/cars
      name: car-vol
    env:
    - name: ilike
...
  securityContext:{}
  volumes:
  - name: car-vol
    configMap::
      defaultMode: 420
      name: fast-car
...

Create PersistentVolume from YAML file

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pvvol-1
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  nfs:
    path: /opt/sfw
    server: cp
    readOnly: false

k create -f PVol.yaml k get pv

Create PersistentVolumeClaim

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-one
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 200Mi

k create -f pvc.yaml

After creating PVC, the status of PV should change to Bound

Use the volume in a Pod

...
spec:
  containers:
  - image: nginx
    volumeMounts:
    - mountPath: /opt
      name: nfs-vol
...
  securityContext:{}
  volumes:
  - name: nfs-vol
    persistentVolumeClaim:
      claimName: pvc-one
...

View the update history of the deployment

k rollout history deployment deploymentName

Compare two deployment revisions

k rollout history deployment deploymentName --revision=1 > one.out
k rollout history deployment deploymentName --revision=2 > two.out
diff one.out two.out

Verify what would be undone while undoing the rollout(show the template prior to using it)

kubectl rollout undo --dry-run=client deployment/deploymentName

Undo rollout to specific revision

kubectl rollout undo deployment deploymentName --to-revision=1