Kubernetes Details

Commands

To get pods

kubectl get pod

To get deployment

kubectl get deployment

To get service

kubectl get service

To get help

kubectl -h

To create deployment

kubectl create deployment deployment-name --image image url

To get replicaset

kubectl get replicaset

To describe deployment

kubectl describe deployment deployment-name

To descibe pod

kubectl describe pod

To chnage deployment

kubectl edit deployment

To check log for a pod

kubectl logs pod-name

To go inside pod

kubectl exec -it podname --bin/bash

To delete deployment

kubectl delete deployment deployment-name

To deploy application with deployment file

kubectl apply -f deploy.yml

Kubernetes namespaces

K8 provides below namespaces

to create namespace

kubectl create namespace my-namespace

to deploy in a namespace

kubectl apply -f user-service.yml --namespace=my-namespace

to get deployemnt in a namespace

kubectl get deployment -n my-namespace

To get pod in a namespace

kubectl get pod -n my-namespace

We can configure namespace in deployment file under metadata section

metadata:

namespace: my-namespace

Kubernetes Health Check

2 types of health check

1. Readiness Probe

Liveness Probe: to check if application is live or not, this is constant checking say every 5 min.

Ingress Component

route the traffic base on routing rule within k8 cluster.

There are 2 types services ,external service -ip for external service are exposed to outside world and for internal service is only exposed in the k8 cluster. User connect on external traffic and then access say DB which is on internal service inside k8 cluster. cluster ip denote ip for internal service while node port and load balancer type denote external service.

Ingress component allow external traffic on k8 cluster based on routing mechanism. We normally access application service with dns name and there should be routing mechanism which can route this dns to respective services. This is where ingress service is being used where we configure hostname, port, path & service.

Ingress make use of Ingress Controller to identify traffic and route it accordingly.

Please check below sample ingress where we define host. For this host, it define routing rule such as path, service and port. Based on this rule, ingress call respective backend service and serve the request.

Please note that host name and its ip we need to map in host.properties