Pulling from private registries in Docker - Commands & Configuration

Introduction

Sometimes, Docker images are stored in private places that need a username and password to access. Pulling from private registries means getting these images safely by logging in first.

When you want to use a Docker image stored in a private company registry.

When you need to deploy an app using images that are not public.

When you want to automate pulling images in a secure way in your CI/CD pipeline.

When you want to share images only with trusted team members.

When you want to keep your app images safe from public access.

Commands

This command logs you into the private Docker registry using your username and password so you can pull images from it.

Terminal

docker login myprivateregistry.com -u myuser -p mypassword

Expected Output

Login Succeeded

→

-u - Specifies the username for login

→

-p - Specifies the password for login

This command pulls the Docker image named 'my-app' with the 'latest' tag from the private registry you logged into.

Terminal

docker pull myprivateregistry.com/my-app:latest

Expected Output

latest: Pulling from my-app

Digest: sha256:abcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890

Status: Downloaded newer image for myprivateregistry.com/my-app:latest

myprivateregistry.com/my-app:latest

This command lists all Docker images on your machine to confirm the private image was downloaded.

Terminal

docker images

Expected Output

REPOSITORY                          TAG       IMAGE ID       CREATED        SIZE

myprivateregistry.com/my-app       latest    123abc456def   2 hours ago    150MB

Key Concept

You must log in to a private registry before pulling images to access them securely.

Common Mistakes

Trying to pull the image without logging in first.

Docker will deny access because it does not have permission to download private images.

Always run 'docker login' with your credentials before pulling private images.

Using the wrong registry URL or image name.

Docker cannot find the image and will show an error.

Double-check the registry address and image name for typos before pulling.

Passing the password directly in the command in shared environments.

This exposes your password in command history and logs.

Use 'docker login' without '-p' to enter the password securely when prompted.

Summary

Log in to the private registry using 'docker login' with your username and password.

Pull the private image using 'docker pull' with the full registry path.

Verify the image is downloaded using 'docker images'.