kubernetes-cheatsheet.md

Kubernetes Cheatsheet

brought to you by Sematext

Client Configuration

• Setup autocomplete in bash; bash-completion package should be installed first

  source <(kubectl completion bash)

• View Kubernetes config

  kubectl config view

• View specific config items by json path

  kubectl config view -o jsonpath='{.users[?(@.name == "k8s")].user.password}'

Manage Resources

• Get documentation for pod or service

  kubectl explain pods,svc

• Create resource(s) like pods, services or daemonsets

  kubectl create -f ./my-manifest.yaml

• Apply a configuration to a resource

  kubectl apply -f ./my-manifest.yaml

• Start a single instance of Nginx

  kubectl run nginx --image=nginx

• Create a secret with several keys

   cat <<EOF | kubectl create -f -
   apiVersion: v1
   kind: Secret
   metadata:
     name: mysecret
   type: Opaque
   data:
     password: $(echo -n "s33msi4" | base64)
     username: $(echo -n "jane" | base64)
   EOF
  

• Delete a resource

  kubectl delete -f ./my-manifest.yaml

Viewing, Finding Resources

• List all services in the namespace

  kubectl get services

• List all pods in all namespaces in wide format

  kubectl get pods -o wide --all-namespaces

• List all pods in json (or yaml) format

  kubectl get pods -o json

• Describe resource details (node, pod, svc)

  kubectl describe nodes my-node

• List services sorted by name

  kubectl get services --sort-by=.metadata.name

• List pods sorted by restart count

  kubectl get pods --sort-by='.status.containerStatuses[0].restartCount'

• Rolling update pods for frontend-v1

  kubectl rolling-update frontend-v1 -f frontend-v2.json

• Scale a replicaset named 'foo' to 3

  kubectl scale --replicas=3 rs/foo

• Scale a resource specified in "foo.yaml" to 3

  kubectl scale --replicas=3 -f foo.yaml

• Execute a command in every pod / replica

  for i in 0 1; do kubectl exec foo-$i -- sh -c 'echo $(hostname) > /usr/share/nginx/html/index.html'; done

Monitoring & Logging

• Deploy Heapster from Github repository https://github.com/kubernetes/heapster

  kubectl create -f deploy/kube-config/standalone/

• Show metrics for nodes

  kubectl top node

  kubectl top node my-node-1

• Show metrics for pods

  kubectl top pod

  kubectl top pod my-pod-1

• Show metrics for a given pod and its containers

  kubectl top pod pod_name --containers

• Dump pod logs (stdout)

  kubectl logs pod_name

• Stream pod container logs (stdout, multi-container case)

  kubectl logs -f pod_name -c my-container

• Create a daemonset from stdin. The example deploys Sematext Docker Agent to all nodes for the cluster-wide collection of metrics, logs and events. There is NO need to deploy cAdvisor, Heapster, Prometheus, Elasticsearch, Grafana, InfluxDb on your local nodes. Please replace YOUR_SPM_DOCKER_TOKEN and YOUR_LOGSENE_TOKEN with your tokens created in Sematext Cloud UI before you run the command.

apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: sematext-agent
spec:
  template:
    metadata:
      labels:
        app: sematext-agent
    spec:
      nodeSelector: {}
      hostNetwork: true
      dnsPolicy: "ClusterFirst"
      restartPolicy: "Always"
      containers:
      - name: sematext-agent
        image: sematext/sematext-agent-docker:latest
        imagePullPolicy: "Always"
        env:
        - name: SPM_TOKEN
          value: "YOUR_SPM_DOCKER_TOKEN"
        - name: LOGSENE_TOKEN
          value: "YOUR_LOGSENE_TOKEN"
        volumeMounts:
          - mountPath: /var/run/docker.sock
            name: docker-sock
          - mountPath: /etc/localtime
            name: localtime
        securityContext:
          privileged: true
      volumes:
        - name: docker-sock
          hostPath:
            path: /var/run/docker.sock
        - name: localtime
          hostPath:
            path: /etc/localtime
EOF