Kubernetes Learning Phase 1 - Basic Commands

This post will only includes scenario based Kubernetes problem and the commands/debugging steps.It will be updated whenever I learn something new.

Installation of Kubernetes refer here: https://kubernetes.io/docs/tasks/tools/

Case 1: Get all pods in a namespace

kubectl get pods -n <namespace_name>

Case 2: Get all namespaces

kubectl get namespaces 

OR

kubectl get ns

Case 3: Create pods with a name and image in a particular namespace

kubectl run <pod_name> --image=<image_name> -n <namespace>

e.g.

kubectl run redis --image=redis -n my-namespace

Case 4: Get all pods in all the namespaces

kubectl get pods --all-namespaces

Case 5: Get all replicasets

kubectl get replicaset

Case 6: Create pods using yaml file

kubectl apply -f abc.yml -n namespace

Content of abc.yaml or abc.yml file:

apiVersion: v1

kind: Pod

metadata: 

  name: new-pod

  label:

    type: linux

spec:

  containers:

    -name: redis

     image: redis

Case 7: Create deployment using yaml file

kubectl apply -f deployment.yml

apiVersion: apps/v1

kind: Deployment

metadata:

  name: new-deployment

spec:

  replicas: 3

  selector:

    matchLabels:

      name: abc-pod

  template:

    metadata:

      labels:

        name: abc-pod

    spec:

      containers:

      - name: abc-container

        image: nginx

        command:

        - sh

        - "-c"

        - echo Hello Kubernetes! && sleep 3600

Here important points are: 

• apiVersion should follow the way apps/v1 or apps/v
• kind is case sensitive
• matchlabels.name should be same as metadata.labels.name
• You can specify the replica number and that many pods will be cretaed.
• When this deployment will be created, a replicaset, 3 pods, one deployment will be created.

Case 8: Get all details of the pod

kubectl describe pod <pod_name> -n <namespace>

Case 9: Get all pods, replicaset, deployment and services present

kubectl get all

Case 10: Editing an existing replicaset

kubectl edit replicaset <replicaset_name>