K8S | The shortest summary every

Concepts :

Pod = a group of one or more containers with shared storage/netweok and a specification of how to run the containers.

Deployment = high-level configuration around a desired function, a deployment provides declarative for Pods and ReplicaSets .

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

Service = Service it’s an “k8s as a service”, by the “kubectl expose” command you will expose your K8s cluster as a service, before running this command, containers inside the pod are able to communicate with each other, but there is no connection from outside .

There are 3 services types : 

ClusterIP = the default type, opens the port on each node for Pod-to-Pod communication .NodePort = if we don’t specify NodePort, K8s randomly assigns a port .LoadBalancer = external IP which act as Load-balancer for the service 

~/.kube/config = configuration file which used by Kubectl .

Some useful Kubectl commands :

• Kubectl get nodes

• Kubectl get pods

• Kubectl create deployment

• Kubectl delete deployment 

• Kubectl expose

• Kubectl run  

• Kubectl scale deployment [DEPLOYMENT_NAME] —replicas=4

(Add pods, by this command our service will run on multiple pods & nodes).