Kubernetes

Kubernetes is an open-source container orchestration system for automating software deployment, scaling, and management. Google originally designed Kubernetes, but the Cloud Native Computing Foundation now maintains the project.

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}'
  

• Set credentials for foo.kuberntes.com

  kubectl config set-credentials kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword
  

• Set active namespace

  kubectl config set-context --current --namespace=namespace_name
  

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
  

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 "s33msi4" | base64)
  username: $(echo "jane"| base64)
  EOF
  

• Delete a resource

  kubectl delete -f ./my-manifest.yaml
  

Monitoring & Logging

• Deploy Heapster from Github repository

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

• Show metrics for nodes

  kubectl top node
  

• Show metrics for pods

  kubectl top pod
  

• 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
  

Interacting with running pods

• Run command in pod

  kubectl exec pod_name -- command_name
  

• Run command in pod with multiple containers

  kubectl exec pod_name -c container_name -- command_name
  

• Get terminal of pod

  kubectl exec -it pod_name /bin/sh
  

• Get terminal of a container running in pod with multiple containers

  kubectl exec -it pod_name -c container_name /bin/sh