Kubernetes Pods

In the previous post we’ve looked into Kubernetes System commands. Now it’s time to start diving deeper into some of the most fundamental building blocks of the Kubernetes ecosystem. Probably the best start is to look deep into the platform and learn about one of the smallest, atomic, yet very important resource – the Pod.

Pod, in its simplest implementation, is essentially your Container running on Kubernetes. You can, technically, run multiple containers in a single Pod. However, for this tutorial we’ll keep it simple to one Pod = one Container.

More details: Kubernetes Pods

Create Pod

Let’s start with creating Pod workloads. You can generally do this either by adopting Imperative or Declarative syntax with the kubectl create command.

More Details: kubectl create

Imperative

kubectl create po [POD NAME]

Declarative

kubectl apply -f [POD TEMPLATE].yaml

[POD TEMPLATE].yaml

apiVersion: v1
kind: Pod
metadata:
  name: [POD NAME]
  labels:
    role: my-role
spec:
  containers:
    - name: my-container
      image: nginx
      ports:
        - name: my-container
          containerPort: 80
          protocol: TCP

List Pods

To find out what Pods are running and in which Namespaces you’ll probably want to use some of these kubectl get po commands. It’s also possible to filter the queries on Pod attributes or fields.

More Details: kubectl get

List All Pods in Namespace

kubectl get po -n [NAMESPACE]

List All Pods in All Namespaces

kubectl get po --all-namespaces

List All Pods with Labels

kubectl get po --all-namespaces --show-labels

List All Pods by Status – Not Running

kubectl get pods --field-selector=status.phase!=Running --all-namespaces

List All Pods by Status – Running

kubectl get pods --field-selector=status.phase==Running --all-namespaces

Pod Details

These commands will allow you to look deeper into your chosen Pod where you’ll find out all the Pod details, labels, specification in either YAML or Wide output.

More Details: kubectl describe

Get Pod

kubectl get po [POD NAME] -n [NAMESPACE]

Get Pod – Wide Output

kubectl get po [POD NAME] -n [NAMESPACE] -o wide

Get Pod – YAML Output

kubectl get po [POD NAME] -n [NAMESPACE] -o yaml

Export Pod – YAML Output to File

kubectl get po [POD NAME] -n [NAMESPACE] -o yaml --export > [FILE NAME].yaml

Describe Pod

kubectl describe po [POD NAME] -n [NAMESPACE]

Patch Pod

To modify an existing Pod directly on the Kubernetes data plane use the kubectl patch command.

More Details: kubectl patch

Patch Pod with bash

kubectl patch po [POD NAME] -n [NAMESPACE] -p "$(cat [POD TEMPLATE].yaml)"

Patch Pod with Powershell

kubectl patch po [POD NAME] -n [NAMESPACE] -p $(Get-Content [POD TEMPLATE].yaml -Raw)

Pod Logs

To access Logs on a running Pod, mainly for debugging or troubleshooting, use the kubectl logs command.

More Details: kubectl logs

Print Pod Logs

kubectl logs [POD NAME] -n [NAMESPACE]

Stream Pod Logs to STDOUT

kubectl logs [POD NAME] -n [NAMESPACE] -f

Run Pod

Now it’s time to start playing with some Pods where you’ll be able to start up a Pod, start & enter (exec) into it or event remove the Pod after exiting from it using the kubectl run command.

More Details: kubectl run

Start Pod

kubectl run [POD NAME] -n [NAMESPACE] --image=[IMAGE NAME] --generator=run-pod/v1

Start Pod & Exec Into

kubectl run -it [POD NAME] -n [NAMESPACE] --image=[IMAGE NAME] --generator=run-pod/v1 -- /bin/ash

Start Pod & Exec Into & Remove it on Exit

kubectl run -it --rm [POD NAME] -n [NAMESPACE] --image=[IMAGE NAME] --generator=run-pod/v1 -- /bin/ash

Execute Pod

If there’s a Pod that is already up and running then entering into it with kubectl exec command will allow you to establish a shell session inside.

More Details: kubectl exec

Exec Into Pod

kubectl exec -it [POD NAME] -n [NAMESPACE] -- /bin/ash

Delete Pod

Finally, to dispose of a Pod simply use the kubectl delete command allowing you to target single Pod or even filter on labels or namespaces.

More Details: kubectl delete

Imperative

Delete Pod By Name

kubectl delete po [POD NAME] -n [NAMESPACE]

Delete Pod By Label

kubectl delete pods -l name=[LABEL] -n [NAMESPACE]

Delete All Pods in Namespace

kubectl delete pods -n [NAMESPACE] --all

Declarative

kubectl delete -f [POD TEMPLATE].yaml

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