K8S Management and Operations

Tags: k8s, operation

• https://kubernetes.io/docs/reference/kubectl/cheatsheet/
• app version: https://matthewpalmer.net/kubernetes-app-developer/articles/kubernetes-apiversion-definition-guide.html
• Sample service tutorial: https://medium.freecodecamp.org/learn-kubernetes-in-under-3-hours-a-detailed-guide-to-orchestrating-containers-114ff420e882
• https://learnk8s.io/troubleshooting-deployments

kubectl config view
kubectl config use-context kubernetes-admin@kubernetes 
kubectl config current-context 
kubectl get nodes 
kubectl apply -f sd-rest-deployment.yaml 
kubectl create -f service-sd-rest-lb.yaml 
kubectl get deployments.
kubectl describe deployments. service-directory
kubectl get service
kubectl describe service service-directory-lb 
curl -v 10.107.178.133:9000
kubectl delete service service-directory-lb 
kubectl delete deployments service-directory 

Helm defines app cluster using yaml.

.http://localhost/~dang/wiki/doku.php?id=virtualization:k8s:02_k8s_day0

Code in golang, python that run in k8s and manage custom resource lifecycle.

• https://kubernetes.io/docs/tasks/debug-application-cluster/debug-application/

Identify pod error

  kubectl get pods
  default       k8s-dashboard-kubernetes-dashboard-696b8cc6f8-jdwxz   0/1     ContainerCreating   0          15m    
  

See pod error/status log:

kubectl describe pods pod-name
# see status report

kubectl logs -p service-directory-7df665dc67-445pg (pod-name)
# see crash output from **previous terminated containe**

• https://kubernetes.io/docs/tasks/debug-application-cluster/get-shell-running-container/

Get a shell to the running Container, the only one in a pod:

kubectl exec -it pod-name -- /bin/bash

The Pod has two containers named main-app and helper-app. The following command would open a shell to the main-app Container.

kubectl exec -it my-pod --container main-app -- /bin/bash

Not using attach b/c it allows only one tty, so:

docker ps -a
CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS         PORTS     NAMES
002af509471f        opnfv/compass-db      "/sbin/entrypoint.sh"    2 minutes ago       Up 2 minutes   3306/tcp  condescending_bartik

docker exec -it -u root 002af509471f /bin/bash

kubectl exec -it service-directory-6b948bd66c-b9qgw -- bash 

check running port

ss -lan
netstat -ntlp

  sudo docker logs e537fb5d99f7
  

Get ippools

  kubectl describe ippools.crd.projectcalico.org default-ipv4-ippool

repo name is image name

• https://docs.docker.com/docker-hub/repos/#pushing-a-docker-container-image-to-docker-hub

To push a repository to the Docker Hub, you must name your local image using your Docker Hub username, and the repository name that you created through Docker Hub on the web.

You can add multiple images to a repository, by adding a specific :<tag> to it (for example docs/base:testing). If it’s not specified, the tag defaults to latest.

You can name your local images either when you build it, using

  docker build -t <hub-user>/<repo-name>[:<tag>]

, by re-tagging an existing local image

  docker tag <existing-image> <hub-user>/<repo-name>[:<tag>]

, or by using

  docker commit <existing-container> <hub-user>/<repo-name>[:<tag>]

to commit changes.

Now you can push this repository to the registry designated by its name or tag.

  $ docker login
  #user: thuydang pass: 1.2.
  
  $ docker push <hub-user>/<repo-name>:<tag>

The image is then uploaded and available for use by your teammates and/or the community.