Vijay Kubernetes Learnings

1. What is POD – in 10 lines with 1 YAML example

Ans: Pod is a group of one or more Containers, A atom inside the container which manages the IP & Port configurations.

below are the list of commands for Pod

kubectl get pods

kubectl create -f pod1.yaml -n=vijay

kubectl apply -f pod1.yaml -n=vijay

kubectl get pods -n=vijay

kubectl get pods -n=vijay-o wide –show-labels

kubectl delete -f pod1.yaml -n=vijay

apiVersion: v1
kind: Pod
metadata:
  name: vijay
  labels:
    app: helloworld
spec:
  containers:
  - name: vjcontainer
    image: scmgalaxy/nginx-vjcontainer
    ports:
    - name: nginx-port
      containerPort: 80

1. What is ReplicationController – in 4 lines with 1 YAML example

Ans: A ReplicationController ensures that a specified number of pod replicas are running at any one time. Replication contains multiple POD.

below are list of commands for ReplicationController

kubectl create -f rc.yaml -n=vijay

kubectl get rc -n=vijay

kubectl apply -f rc.yaml -n=vijay

kubectl delete rc replicationcontroller-example -n=vijay

apiVersion: v1
kind: ReplicationController
metadata:
  name: replicationcontroller-example
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: scmgalaxy/nginx-devopsschoolv1

1. What is ReplicaSets – in 4 lines with 1 YAML example

Ans: A ReplicaSet’s purpose is to maintain a stable set of replica Pods running at any given time.

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-example
  labels:
    app: guestbook
    tier: frontend
spec:
  # modify replicas according to your case
  replicas: 3
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
        tier: frontend
    spec:
      containers:
      - name: php-redis
        image: gcr.io/google_samples/gb-frontend:v3

1. What is Deployment – in 10 lines with 1 YAML example

Ans: A Deployment provides declarative updates for Pods and ReplicaSets.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80