Kubectl Commands

To get kubernetes cluster info.

$ kubectl cluster-info
Kubernetes control plane is running at https://192.168.49.2:8443
CoreDNS is running at https://192.168.49.2:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

To get node information created by minikube

$ kubectl get nodes
NAME       STATUS   ROLES           AGE   VERSION
minikube   Ready    control-plane   15h   v1.28.3

To get pods informations

$ kubectl get pods
No resources found in default namespace.

Note: This command returns pods informations that are present in default namespace.

Namespaces are used to group different resources and configurations. To get namespace information:

$ kubectl get namespaces
NAME              STATUS   AGE
default           Active   15h
kube-node-lease   Active   15h
kube-public       Active   15h
kube-system       Active   15h

To get pods running in a specific namespace.

$ kubectl get pods --namespace=kube-system
NAME                               READY   STATUS    RESTARTS      AGE
coredns-5dd5756b68-wzz75           1/1     Running   1 (15h ago)   16h
etcd-minikube                      1/1     Running   1 (15h ago)   16h
kube-apiserver-minikube            1/1     Running   1 (15h ago)   16h
kube-controller-manager-minikube   1/1     Running   1 (15h ago)   16h
kube-proxy-db2cf                   1/1     Running   1 (15h ago)   16h
kube-scheduler-minikube            1/1     Running   1 (15h ago)   16h
storage-provisioner                1/1     Running   3 (18m ago)   16h

To run nginx docker image inside of a pod.

$ kubectl run nginx --image=nginx
pod/nginx created

The nginx is the name of the pod and --image=nginx specifies the name of docker image from dockerhub.

$ kubectl get pods
NAME    READY   STATUS              RESTARTS   AGE
nginx   0/1     ContainerCreating   0          15s

$ kubectl get pods
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          4m20s

To view detailed information about the pods.

$ kubectl describe pods
Name:             nginx
Namespace:        default
Priority:         0
Service Account:  default
Node:             minikube/192.168.49.2
Start Time:       Tue, 23 Jan 2024 10:51:47 +0530
Labels:           run=nginx
Annotations:      <none>
Status:           Running
IP:               10.244.0.4
IPs:
  IP:  10.244.0.4
Containers:
  nginx:
    Container ID:   docker://eaf445e826d40b29c18a8925648cf7d0d4249c381a3d6fc4deaef69f2a92c1ea
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:4c0fdaa8b6341bfdeca5f18f7837462c80cff90527ee35ef185571e1c327beac
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Tue, 23 Jan 2024 10:55:48 +0530
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-fv2bm (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  kube-api-access-fv2bm:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age    From               Message
  ----    ------     ----   ----               -------
  Normal  Scheduled  5m29s  default-scheduler  Successfully assigned default/nginx to minikube
  Normal  Pulling    5m28s  kubelet            Pulling image "nginx"
  Normal  Pulled     88s    kubelet            Successfully pulled image "nginx" in 4m0.152s (4m0.152s including waiting)
  Normal  Created    88s    kubelet            Created container nginx
  Normal  Started    88s    kubelet            Started container nginx

Get container informations by logging in to node.

$ minikube ssh
docker@minikube:~$ docker ps | grep nginx
eaf445e826d4   nginx                       "/docker-entrypoint.…"   15 minutes ago   Up 15 minutes             k8s_nginx_nginx_default_6d27b85e-d4c7-44c8-9852-c9731b376fb4_0
aee51b35b689   registry.k8s.io/pause:3.9   "/pause"                 19 minutes ago   Up 19 minutes             k8s_POD_nginx_default_6d27b85e-d4c7-44c8-9852-c9731b376fb4_0

The 'pause' container is a container which holds the network namespace for the pod. Kubernetes creates pause containers to acquire the respective pod’s IP address and set up the network namespace for all other containers that join that pod.
Log in the container and ping the nginx server.

$ docker exec -it eaf445e826d4 sh  
# hostname
nginx
# hostname -i
10.244.0.4
#  curl 10.244.0.4
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
# exit

Get IP Address of all containers running in the pods using kubectl.

$ kubectl get pods -o wide
NAME    READY   STATUS    RESTARTS   AGE   IP           NODE       NOMINATED NODE   READINESS GATES
nginx   1/1     Running   0          37m   10.244.0.4   minikube   <none>           <none>

To delete pods.

$ kubectl delete pod nginx
pod "nginx" deleted

To scale the deployments

$ kubectl scale deployment nginx-deployment --replicas=5
deployment.apps/nginx-deployment scaled