How to Select the Best Container Registry

If you are developing any type of containerized application, there will be some concerns for you as a developer or an ops engineer. One such major concern is where to store the container images so that they can be easily and securely accessible at the deployment. This is where container registries come into play by offering a place to store these images. Therefore, selecting the best possible container registry for your specific use case is vital in any containerized application development. Yet, how can we ensure that we select the best possible registry? Let's try to answer that question in this post.

What is a Container Registry?

Before looking at selecting a registry, we need to properly understand the functionality of a container registry. As the name suggests, a container registry acts as a registry that can be used to store container images. These images can then be searched, downloaded, and used in any container deployment, including deployments in orchestration engines like Kubernetes.

These registries can act as standalone entities for developers to store and distribute their images or as an integral part of a CI/CD pipeline. There are two types of registries; public registries that are publicly accessible and private registries that are only accessible for authorized users. Some examples of container registries are;

• Docker Hub
•  Harbour
• Amazon Elastic Container Registry (ECR)
• Azure Container Registry (ACR)
• GitHub Package Registry
• Google Artifact Registry
• RedHat Quay
  

How to Select the Right Container Registry?

When selecting a container registry, the first consideration is what type of repository to use. A public repository will suffice for a simple hobbyist project or a container without proprietary information. Yet, the only choice for any other requirement should be a private repository, unless you intend to share your application freely. Even so, it is always better to go with a private repository for the development.

Managed or Self-Hosted

Even when considering a private repo, the next question is whether to self-host or use a managed service. Self-hosted services offer you full control of your registry, from where it is hosted to all the underlying configurations. Even if you encounter an error like imagepullbackoff with a self-hosted option, you have full control over the registry as well as the deployment to quickly diagnose and rectify the issue. On the other hand, a managed service eliminates the need for managing the registry and provides nearly unlimited scalability. Managed services can also be simpler to integrate with some CI/CD tools, as they provide native integrations for these services.

Artifacts other than Container Images

Some environments will require storing artifacts such as node and python packages within the registry other than container images. While code, build, and configuration files can be stored within a Git repo, other build packages might need to be stored separately. Thus, you require a registry that supports containers as well as other artifact types.

Security of the Registry

As with any software, the security of the product takes a center point in selecting a registry. Security of the registry can be determined by the available authentication options, network security, security and control options over the store images, and even the ability to scan uploaded containers for vulnerabilities. Backup and recovery options should also be evaluated as a part of the overall security architecture of the registry. Some registry providers like Azure provide detailed information on the security baseline for their container registry. It is always recommended to select a registry that provides the best available security options to securely maintain the registry without negatively impacting the overall usability.

Performance and Cost of the Registry

The lower the latency between your registry and the deployment environment, the higher the performance will be. While this fact may seem negligible, saving time when pulling images from the registry can add to a lot of time savings when dealing with a larger number of images with multiple deployments. So, if you are bound to a particular provider, using a registry service offered by that provider will provide you with the best possible performance. Costs must also be considered when selecting a registry. While self-hosting may be cheaper initially, the cost can quickly add up with the management requirements. Even though managed options can be cheaper in the long term, storage costs and data
transfer costs can balloon up if they are not managed properly. Again,
selecting a managed option from the same provider as your current environment can help reduce the overall costs associated with the registry.

Conclusion

All the factors mentioned above need to be considered before selecting a container registry. Managed options are the preferred solution unless there are policy or compliance requirements that enforce the use of a self-hosted registry. Either way, you need to decide where to host the registry and what features you require, and finally select the registry that best suits your container deployment environment.