> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Commands and Arguments in Kubernetes

> This tutorial explains how to configure commands and arguments in a Kubernetes Pod using the ubuntu-sleeper image.

In this tutorial, you’ll learn how to configure **commands** and **arguments** in a Kubernetes Pod. We’ll use a simple `ubuntu-sleeper` image that demonstrates how `ENTRYPOINT` and `CMD` from a Dockerfile map to the `command` and `args` fields in a Pod spec.

***

## Table of Contents

1. [Recap: ubuntu-sleeper Docker Image](#recap-ubuntu-sleeper-docker-image)
2. [Create a Pod with the Default Command](#create-a-pod-with-the-default-command)
3. [Override CMD with `args`](#override-cmd-with-args)
4. [Override ENTRYPOINT with `command`](#override-entrypoint-with-command)
5. [Summary & Mapping Table](#summary--mapping-table)
6. [References](#references)

***

## Recap: ubuntu-sleeper Docker Image

We built a minimal Docker image called **ubuntu-sleeper**:

```dockerfile theme={null}
FROM ubuntu
ENTRYPOINT ["sleep"]
CMD ["5"]
```

* Running without extra arguments uses the default sleep duration (5 seconds):
  ```bash theme={null}
  docker run --name ubuntu-sleeper ubuntu-sleeper
  ```
* Providing an argument overrides `CMD` (for example, sleep 10):
  ```bash theme={null}
  docker run --name ubuntu-sleeper ubuntu-sleeper 10
  ```

In Docker CLI, anything after the image name replaces the `CMD` instruction.

***

## Create a Pod with the Default Command

Here’s the simplest Pod manifest that runs `sleep 5` by default:

```yaml theme={null}
apiVersion: v1
kind: Pod
metadata:
  name: ubuntu-sleeper-pod
spec:
  containers:
    - name: ubuntu-sleeper
      image: ubuntu-sleeper
```

Apply the Pod:

```bash theme={null}
kubectl create -f pod-definition.yml
```

By default, Kubernetes uses the image’s `ENTRYPOINT` + `CMD` (`sleep 5`), and the container will exit after 5 seconds.

***

## Override CMD with `args`

To change the sleep duration without touching the entrypoint, specify an `args` array in your Pod spec:

```yaml theme={null}
apiVersion: v1
kind: Pod
metadata:
  name: ubuntu-sleeper-pod
spec:
  containers:
    - name: ubuntu-sleeper
      image: ubuntu-sleeper
      args: ["10"]
```

This runs `sleep 10`. Update the Pod:

```bash theme={null}
kubectl apply -f pod-definition.yml
```

<Callout icon="lightbulb" color="#1CB2FE">
  The `args` field in Kubernetes corresponds directly to the Dockerfile `CMD`. Any elements you list here will override the default `CMD` values.
</Callout>

***

## Override ENTRYPOINT with `command`

If you need to override both the entrypoint and its arguments, use the `command` field for the entrypoint and `args` for its parameters:

```yaml theme={null}
apiVersion: v1
kind: Pod
metadata:
  name: ubuntu-sleeper-pod
spec:
  containers:
    - name: ubuntu-sleeper
      image: ubuntu-sleeper
      command: ["sleep2.0"]
      args: ["10"]
```

* `command` replaces the Dockerfile `ENTRYPOINT`.
* `args` replaces the Dockerfile `CMD`.

Apply this configuration:

```bash theme={null}
kubectl create -f pod-definition.yml
```

<Callout icon="triangle-alert" color="#FF6B6B">
  If you override the `command` field, make sure the specified executable exists in the container filesystem. Otherwise, the Pod will fail to start.
</Callout>

***

## Summary & Mapping Table

The table below summarizes how Dockerfile instructions map to Kubernetes Pod spec fields:

| Dockerfile Instruction | Kubernetes Pod Spec Field | Purpose                               |
| ---------------------- | ------------------------- | ------------------------------------- |
| ENTRYPOINT             | command                   | Defines the executable to run         |
| CMD                    | args                      | Provides default parameters/arguments |

Use these fields to precisely control the process invoked inside your containers.

***

## References

* [Kubernetes Official Documentation](https://kubernetes.io/docs/)
* [Dockerfile reference](https://docs.docker.com/engine/reference/builder/)
* [Managing Containers in Pods](https://kubernetes.io/docs/concepts/workloads/pods/)

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