Commands and Arguments in Kubernetes

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.

Recap: ubuntu-sleeper Docker Image
Create a Pod with the Default Command
Override CMD with args
Override ENTRYPOINT with command
Summary & Mapping Table
References

Recap: ubuntu-sleeper Docker Image

We built a minimal Docker image called ubuntu-sleeper:

FROM ubuntu
ENTRYPOINT ["sleep"]
CMD ["5"]

Running without extra arguments uses the default sleep duration (5 seconds):
docker run --name ubuntu-sleeper ubuntu-sleeper
Providing an argument overrides CMD (for example, sleep 10):
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:

apiVersion: v1
kind: Pod
metadata:
  name: ubuntu-sleeper-pod
spec:
  containers:
    - name: ubuntu-sleeper
      image: ubuntu-sleeper

Apply the Pod:

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:

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:

kubectl apply -f pod-definition.yml

The args field in Kubernetes corresponds directly to the Dockerfile CMD. Any elements you list here will override the default CMD values.

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:

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:

kubectl create -f pod-definition.yml

If you override the command field, make sure the specified executable exists in the container filesystem. Otherwise, the Pod will fail to start.

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.

Introduction

Docker Engine

Docker Image Management

Docker Engine - Security

Docker Engine - Networking

Docker Engine - Storage

Docker Compose

Docker Swarm

Kubernetes

Docker Engine Enterprise

Docker Trusted Registry

Disaster Recovery

Commands and Arguments in Kubernetes

Table of Contents

Recap: ubuntu-sleeper Docker Image

Create a Pod with the Default Command

Override CMD with `args`

Override ENTRYPOINT with `command`

Summary & Mapping Table

References

Watch Video

​Table of Contents

​Recap: ubuntu-sleeper Docker Image

​Create a Pod with the Default Command

​Override CMD with args

​Override ENTRYPOINT with command

​Summary & Mapping Table

​References

Watch Video

Table of Contents

Recap: ubuntu-sleeper Docker Image

Create a Pod with the Default Command

Override CMD with `args`

Override ENTRYPOINT with `command`

Summary & Mapping Table

References