Pod with Command and Args

Why use command and args?

A container image has a default command that runs when the container starts. Sometimes we want the container to run a different command, or run the same command with different arguments.

In a Pod manifest, command replaces the image's default command, and args supplies arguments to that command. If you set only args, Kubernetes uses the image's default command with those arguments.

Create a BusyBox Pod

BusyBox is a small image that includes common command-line tools. It is useful for simple examples and troubleshooting.

Imperative command

kubectl run busybox-pod --image=busybox:1.36 --command -- sh -c 'echo "Hello from busybox"; sleep 300'

Manifest Create a file named 2-pod-with-cmd.yaml with this content:

apiVersion: v1
kind: Pod
metadata:
  name: busybox-pod
spec:
  containers:
  - name: busybox-container
    image: busybox:1.36
    command: ["sh", "-c"]
    args: ["echo 'Hello from BusyBox'; sleep 300"]

Here, command starts a shell, and args tells the shell to print a message and then wait for 5 minutes. The wait keeps the container running so that we can inspect it.

Create the Pod:

kubectl apply -f 2-pod-with-cmd.yaml

kubectl apply -f 2-pod-with-cmd.yaml
pod/busybox-pod created

Check its status:

kubectl get pods

kubectl get pods
NAME          READY   STATUS    RESTARTS   AGE
busybox-pod   1/1     Running   0          10s

Check the message printed by the command:

kubectl logs busybox-pod

kubectl logs busybox-pod
Hello from BusyBox