How to verify the status of a Pod created by kubectl run command?

Verifying the Status of a Pod Created by kubectl run Command

When you create a Pod using the kubectl run command in Kubernetes, it's important to verify the status of the Pod to ensure that it's running as expected. Here's how you can do it:

Checking the Pod Status

After running the kubectl run command to create a new Pod, you can use the kubectl get pods command to check the status of the Pod. This command will display the current state of the Pod, including its name, the node it's running on, the status, and the age of the Pod.

Here's an example:

$ kubectl get pods
NAME          READY   STATUS    RESTARTS   AGE
my-pod        1/1     Running   0          2m

In this example, the Pod named my-pod is in the Running state, which means it's up and running as expected.

If the Pod is not in the Running state, you can check the status further by using the kubectl describe pods command. This command will provide more detailed information about the Pod, including any errors or events that may have occurred during its creation or execution.

$ kubectl describe pods my-pod
Name:         my-pod
Namespace:    default
Priority:     0
Node:         worker1/192.168.1.100
Start Time:   Tue, 18 Apr 2023 14:30:00 +0000
Labels:       run=my-pod
Annotations:  <none>
Status:       Running
IP:           10.244.1.5
IPs:
  IP:           10.244.1.5
Containers:
  my-container:
    Container ID:   docker://6a1234567890abcdef
    Image:          nginx:latest
    Image ID:       docker-pullable://nginx@sha256:1234567890abcdef
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Tue, 18 Apr 2023 14:30:01 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-m4c7m (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  2m    default-scheduler  Successfully assigned default/my-pod to worker1
  Normal  Pulling    2m    kubelet            Pulling image "nginx:latest"
  Normal  Pulled     2m    kubelet            Successfully pulled image "nginx:latest" in 1.234s
  Normal  Created    2m    kubelet            Created container my-container
  Normal  Started    2m    kubelet            Started container my-container

The kubectl describe pods command provides a wealth of information about the Pod, including its status, the containers running inside it, and any events that have occurred during its lifecycle.

Monitoring Pod Status Changes

You can also monitor the status of the Pod in real-time using the kubectl get pods -w command. This command will continuously watch the Pod and display any changes to its status.

$ kubectl get pods -w
NAME          READY   STATUS    RESTARTS   AGE
my-pod        0/1     Pending   0          0s
my-pod        0/1     Pending   0          1s
my-pod        0/1     Pending   0          2s
my-pod        1/1     Running   0          3s

In this example, the Pod initially starts in the Pending state, and then transitions to the Running state after a few seconds.

Understanding Pod Statuses

Kubernetes Pods can have several different statuses, including:

• Pending: The Pod has been accepted by the Kubernetes system, but one or more of the containers has not been created or started yet.
• Running: The Pod has been bound to a node, and all of the containers have been created. At least one container is still running, or is in the process of starting or restarting.
• Succeeded: All containers in the Pod have terminated successfully and will not be restarted.
• Failed: All containers in the Pod have terminated, and at least one container has terminated in failure.
• Unknown: The state of the Pod could not be obtained, usually due to an error in communicating with the host.

Understanding these different statuses can help you troubleshoot issues with your Pods and ensure that they are running as expected.

Visualizing Pod Status with Mermaid

Here's a Mermaid diagram that illustrates the different Pod statuses and the transitions between them:

This diagram shows that a Pod can start in the Pending state, then transition to the Running state, and finally end up in either the Succeeded or Failed state. The Unknown state can occur at any point during the Pod's lifecycle if there's an issue communicating with the host.

By understanding the different Pod statuses and how they relate to each other, you can more effectively monitor and troubleshoot your Kubernetes deployments.