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To start with anything on command line: To understand the meaning of yaml files use

      Kubectl explain <objecttype>
      Kubectl explain pods
      Kubectl explain pods.spec

To see the logs of a container

docker logs <container id>
kubectl logs <podname> 
kubectl logs <podname> -c <containername>

Container logs are automatically rotated daily and every time the log file reaches 10MB in size. The kubectl logs command only shows the log entries from the last rotation.

Know more about your kubectl and cluster

kubectl version
kubectl cluster-info
kubectl config current-context
kubectl get componentstatus

generic commands

kubectl describe <objecttype> <objectname>
kubectl edit <objecttype> <objectname>
kubectl delete <objecttype> <objectname>

Creating any object in kubernetes

kubectl create -f <object.yaml>

modifying an object

kubectl apply -f <object.yaml>

Get the service acccounts

kubectl get serviceaccounts

K8s api server details

kubectl get pod/kube-apiserver-kubemaster-01 -n kube-system -o json

get deployment reated info

kubectl get deploy/<deplyment-name> -o json

Rollback

First look at the revision names of the deployments:

kubectl rollback history deploy/<deployment-name>

Pick a version from the past and rollback

kubectl rollback

Get info about other objects

secrets

kubectl get secrets
kubectl describe secret/default-token-3dj6w
kubectl get secret/default-token-3dj6w -o json

Role

kubectl get role/<role-name> -o json
kubectl get rolebinding/<rolebinding-name> -o json

Pods

kubectl get pods --all-namespaces
kubectl get pods
kubectl describe pod/<podname>
kubectl describe pod/<podname> -o json|wide

Entering into a container running inside a pod :

kubectl exec <podname> -c <containername>  -i -t -- bash
kubectl exec -it <containername> -- /bin/bash

labels

kubectl get pods --show--labels
kubectl get pods --selector <key-label>=<value-label>
kubectl get pods -l <key-label>=<value-label>
kubectl get pods -l '<label-name> in (label-value1, label-value2)'
e.g. : kubectl get pods -l 'env in (dev, prod)'

Investigating the logs:

Controller Deployment logs kubectl get deploy/ -o json

pod logs kubectl logs pod/

To get more columns in the result use -L

kubectl get po -L creation_method,env
NAME            READY   STATUS    RESTARTS   AGE   CREATION_METHOD   ENV
kubia-manual    1/1     Running   0          16m   <none>            <none>
kubia-manual-v2 1/1     Running   0          2m    manual            prod
kubia-zxzij     1/1     Running   0          1d    <none>            <none>

To get more all the pods that have label creation_method:manual

kubectl get po -l creation_method=manual

To list all pods that include the env label, whatever its value is:

kubectl get po -l env
NAME              READY     STATUS    RESTARTS   AGE
kubia-manual-v2   1/1       Running   0          37m

namespaces

kubectl config set-context current-context --name-space name-space-name

When you want to figure out why the previous container terminated, you’ll want to see those logs instead of the current container’s logs. This can be done by using the --previous option:

kubectl logs mypod --previous

Instead of using the kubectl scale command, you’re going to scale it in a declarative way by editing the ReplicationController’s definition:

kubectl edit rc kubia

When deploying a pod, you don’t need to constantly poll the list of pods by repeatedly executing kubectl get pods. Instead, you can use the --watch flag and be notified of each creation, modification, or deletion of a pod,

kubectl get pods --watch

Both the Control Plane components and the Kubelet emit events to the API server as they perform these actions. They do this by creating Event resources, which are like any other Kubernetes resource.

      kubectl get events --watch

Remove the taints on the master so that you can schedule pods on master as well.

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

Run Kubectl with better logging to see what kubectl is doing.

      kubectl get pods -v=8

Never do this

kubectl delete all --all