Verifying installation with docker run hello-world - Commands & Configuration

Introduction

After installing Docker, you need to check if it works correctly. Running a simple test container helps confirm that Docker is set up and running on your computer.

Right after installing Docker to confirm the installation was successful

When you want to check if Docker service is running properly

Before starting to build or run your own containers to ensure the environment is ready

When troubleshooting Docker issues to verify basic container execution

To demonstrate Docker functionality to someone new learning about containers

Commands

This command downloads a small test image called 'hello-world' and runs it as a container. It prints a message to confirm Docker is working.

Terminal

docker run hello-world

Expected Output

Unable to find image 'hello-world:latest' locally

latest: Pulling from library/hello-world

Digest: sha256:7e4a6f1a1a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3a3f3

Status: Downloaded newer image for hello-world:latest



Hello from Docker!

This message shows that your installation appears to be working correctly.



To generate this message, Docker took the following steps:

 1. The Docker client contacted the Docker daemon.

 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.

 3. The Docker daemon created a new container from that image which runs the executable that produces the output you are currently reading.

 4. The Docker daemon streamed that output to the Docker client, which sent it to your terminal.



To try something more ambitious, you can run an Ubuntu container with:

 $ docker run -it ubuntu bash



Share images, automate workflows, and more with a free Docker ID:

 https://hub.docker.com/



For more examples and ideas, visit:

 https://docs.docker.com/get-started/

Key Concept

If you remember nothing else from this pattern, remember: running 'docker run hello-world' confirms Docker is installed and working by running a simple test container.

Common Mistakes

Running 'docker run hello-world' without Docker service running

The command fails because Docker daemon is not active to run containers.

Start the Docker service before running the command, for example 'sudo systemctl start docker' on Linux.

Expecting the command to run instantly without internet connection

Docker needs to download the 'hello-world' image the first time, so it requires internet access.

Ensure your computer is connected to the internet when running the command for the first time.

Summary

Run 'docker run hello-world' to test if Docker is installed and working.

The command downloads and runs a small test container that prints a confirmation message.

If the message appears, Docker is ready for use on your system.