Kubernetes Pod - ReplicationController - ReplicaSet

Structure of pod-definition.yml:

apiVersion: v1
kind: Pod
metadata:
   name: nginx-pod
   labels:
      app: nginx-app
      type: pod
spec:
   containers:
      - name: nginx-container
        image: nginx

Basic Pod commands:

• kubectl create -f pod-definition.yml
• kubctl get pods
• kubeclt get pods -o wide
• kubectl get pod nginx-pod
• kubectl describe pods nginx-pod

Structure of replicationcontroller-definition.yml:

apiVersion: v1
kind: ReplicationController
metadata:
   name: nginx-rc
   labels:
      app: nginx-rc
      type: front-end
spec:
   template:
      metadata:
         name: nginx-pod
         labels:
            app: nginx-app
            type: front-end
      spec:
         containers:
            - name: nginx-container
              image: nginx
   replicas: 3

Basic replication controller commands:

• kubectl create -f replicationcontroller-definition.yml
• kubectl get replicationcontrollers
• kubectl get rc # short form for replicationcontroller
• kubctl delete replicationcontroller/nginx-rc

Structure of replicaset-definition.yml:

apiVersion: apps/v1
kind: ReplicaSet
metadata:
   name: demo-replicaset
   labels:
      app: demo-app
      type: front-end
spec:
   template:
      metadata:
         name: demo-pod
         labels:
            app: demo-app
            type: front-end
      spec:
         containers:
            - name: nginx-container
              image: nginx
   replicas: 3
   selector:
      matchLabels:
         type: front-end

Basic commands for replicaset:

• kubectl create -f replicatset-definition.yml
• kubectl replace -f replicatset-definition.yml #replace the existing replicaset
• kubectl scale –replicas=6 -f replicaset-definition.yml #scale up the replica to 6. Notes: the above command will not change replicaset insde the replicaset-definition.yml file
• kubectl scale –replicas=6 replicaset demo-replicaset
• kubectl get rs
• kubectl edit rs demo-replicaset
• kubectl delete replicaset demo-replicaset # that will delete replicaset and all the underlying pods
• kubectl delete rs demo-replicaset #short form of replicaset