Skip to content

What are Image Registries

A registry is a repository used to store and access container images. Container registries can support container-based application development, often as part of DevOps processes.

Container registries save developers valuable time in the creation and delivery of cloud-native applications, acting as the intermediary for sharing container images between systems. They essentially act as a place for developers to store container images and share them out via a process of uploading (pushing) to the registry and downloading (pulling) into another system, like a Kubernetes cluster.

Some examples of an image registry are Red Hat Quay and IBM Cloud Registry.

Learn More

Quay Tutorial

Make sure you have Podman Desktop installed and up and running.

Here's how to find a list of publicly available container images on DockerHub.

Find Container Image
podman search docker.io/busybox
Output:
NAME                                         DESCRIPTION
docker.io/library/busybox                    Busybox base image.
docker.io/rancher/busybox
docker.io/openebs/busybox-client
docker.io/antrea/busybox
docker.io/hugegraph/busybox                  test image
...

We can create a busybox container image based off of the busybox base image you see listed in the output above.

Create Image
podman run -it docker.io/library/busybox

The -it flag allows you to run the image in interactive mode. Interactive mode in Podman allows you to run a shell in a container and interact with it. However, you'll see that running small containers like this one don't have much to play around with in the interactive mode. To exit out of the interactive mode:

Exit Interactive mode
exit

You can also share images in a public registry so that others can use and review them. Here's how to push your image up to quay.io.

Login to quay.io
podman login quay.io
Enter in the following info:

Username: your_username
Password: your_password

Next, tag the image so that you can push it and find it in your account.

Tag Image
podman tag <image_name> quay.io/your_username/image_registry_name

Make sure to replace "image_name" with the name of the image you want to push up to quay. Replace "user_name" with your quay.io username. Replace "image_registry_name" with what you want the image to be named/labeled as in quay.

Once the image is tagged, you can push it up to quay.

Push Image
podman push quay.io/your_username/image_registry_name

Your respository has now been pushed to Quay Container Registry!

To view your repository, click on the button below:

Repositories

Make sure you have Docker Desktop installed and up and running.

Login to Quay
docker login quay.io
Username: your_username
Password: your_password
Email: your_email

First we'll create a container with a single new file based off of the busybox base image:

Create a new container
docker run busybox echo "fun" > newfile
The container will immediately terminate, so we'll use the command below to list it: 
docker ps -l
The next step is to commit the container to an image and then tag that image with a relevant name so it can be saved to a respository.

Replace "container_id" with your container id from the previous command.

Create a new image
docker commit container_id quay.io/your_username/repository_name
Be sure to replace "your_username" with your quay.io username and "respository_name" with a unique name for your repository.

Now that we've tagged our image with a repository name, we can push the respository to Quay Container Registry:

Push the image to Quay
docker push quay.io/your_username/repository_name
Your respository has now been pushed to Quay Container Registry!

To view your repository, click on the button below:

Repositories

IBM Cloud Registry Tutorial

Before you begin, you need to install the IBM Cloud CLI so that you can run the IBM Cloud ibmcloud commands.

Install the container-registry CLI
ibmcloud plugin install container-registry

Then, you need to create a namespace. The namespace is created in the resource group that you specify so that you can configure access to resources within the namespace at the resource group level. If you don't specify a resource group, then the default is used.

Log in to IBM Cloud
ibmcloud login

Create namespace
ibmcloud cr namespace-add my_namespace
Make sure to replace "my_namespace" with your preferred namespace.

If you want to create the namespace in a specific resource group, use the following code before creating the namespace.

Specify a resource group
ibmcloud target -g resource_group
Replace "resource_group" with the resource group you want to create the namespace in.

Validate namespace is created
ibmcloud cr namespace-list -v

Next, you can pull images from IBM Cloud Registry to your local computer. Make sure Docker is installed and up and running.

Pull image to local computer
docker pull source_image:tag
Replace "source_image" with ther respository of the image and "tag" with the tag of the image that you want to use. Below is an example.

docker pull hello-world:latest

Learn More about Quay Learn More about ICR