#Pods

#Understanding Pods

Refer to the official Kubernetes website documentation: Pod

A Pod is the smallest deployable unit of computing that you can create and manage in Kubernetes. A Pod (as in a pod of whales or a pea pod) is a group of one or more containers (such as containers), with shared storage and network resources, and a specification for how to run the containers. Pods are the fundamental building blocks on which all higher-level controllers (like Deployments, StatefulSets, DaemonSets) are built.

#YAML file example

apiVersion: v1
kind: Pod
metadata:
  name: my-nginx-pod
  labels:
    app: nginx
spec:
  containers:
    - name: nginx
      image: nginx:latest # The container image to use.
      ports:
        - containerPort: 80 # Container ports exposed.
      resources: # Defines CPU and memory requests and limits for the container.
        requests:
          cpu: '100m'
          memory: '128Mi'
        limits:
          cpu: '200m'
          memory: '256Mi'

#Managing a Pod by using CLI

While Pods are often managed by higher-level controllers, direct kubectl operations on Pods are useful for troubleshooting, inspection, and ad-hoc tasks.

#Viewing a Pod

• To list all Pods in the current namespace:

  kubectl get pods

• To list all Pods across all namespaces:

  kubectl get pods --all-namespaces
  # Or a shorter version:
  kubectl get pods -A

• To get detailed information about a specific Pod:

  kubectl describe pod <pod-name> -n <namespace>
  
  # Example
  kubectl describe pod my-nginx-pod -n default

#Viewing a Pod Logs

• To stream logs from a container within a Pod (useful for debugging):

  kubectl logs <pod-name> -n <namespace>

• If a Pod has multiple containers, you must specify the container name:

  kubectl logs <pod-name> -c <container-name> -n <namespace>

• To follow the logs (stream new logs as they appear):

  kubectl logs -f <pod-name> -n <namespace>

#Executing Commands in a Pod

To execute a command inside a specific container within a Pod (useful for debugging, like accessing a shell):

kubectl exec -it <pod-name> -n <namespace> -- <command>

# Example (to get a shell):
kubectl exec -it my-nginx-pod -n default -- /bin/bash

#Port Forwarding to a Pod

To forward a local port to a port on a Pod, allowing direct access to a service running inside the Pod from your local machine (useful for testing or direct access without exposing the service externally):

kubectl port-forward <pod-name> <local-port>:<pod-port> -n <namespace>

#Example
kubectl port-forward my-nginx-pod 8080:80 -n default

After running this command, you can access the Nginx web server running in my-nginx-pod by visiting localhost:8080 in your web browser.

#Deleting a Pod

• To delete a specific Pod:

  kubectl delete pod <pod-name> -n <namespace>
  
  # Example
  kubectl delete pod my-nginx-pod -n default

• To delete multiple Pods by their names:

  kubectl delete pod <pod-name-1> <pod-name-2> -n <namespace>

• To delete Pods based on a label selector (e.g., delete all Pods with the label app=nginx):

  kubectl delete pods -l app=nginx -n <namespace>

#Managing a Pod by using web console

#Viewing a Pod

The platform interface provides various information about the pods for quick reference.

#Procedure

1. Container Platform, navigate to Workloads > Pods in the left sidebar.

2. Locate the Pod you wish to view.

3. Click the deployment name to see the Details, YAML, Configuration, Logs, Events, Monitoring, etc.

#Pod Parameters

Below are some parameter explanations:

#Deleting a Pod

Deleting pods may affect the operation of computing components; please proceed with caution.

#Use Cases

• Restore the pods to its desired state promptly: If a pods remains in a state that affects business operations, such as Pending or CrashLoopBackOff, manually deleting the pods after addressing the error message can help it quickly return to its desired state, such as Running. At this time, the deleted pods will be rebuilt on the current node or rescheduled.

• Resource cleanup for operations management: Some podss reach a designated stage where they no longer change, and these groups often accumulate in large numbers, complicating the management of other podss. The podss to be cleaned up may include those in the Evicted status due to insufficient node resources or those in the Completed status triggered by recurring scheduled tasks. In this case, the deleted podss will no longer exist.

  Note: For scheduled tasks, if you need to check the logs of each task execution, it is not recommended to delete the corresponding Completed status podss.

#Procedure

1. Go to Container Platform.

2. In the left navigation bar, click Workloads > Pods.

3. (Delete individually) Click the ⋮ on the right side of the pods to be deleted > Delete, and confirm.

4. (Delete in bulk) Select the podss to be deleted, click Delete above the list, and confirm.