As containerization has grown in popularity, the industry has witnessed the emergence of multiple container runtimes such as Docker Engine, CRI-O, and rkt, to name a few. Among these, Docker Engine has remained the most popular container runtime for quite some time. However, recently, a new container runtime called Containerd has emerged as a worthy competitor to Docker Engine. So, in this blog, we will explore Docker versus Containerd and their relevance with Kubernetes.
What is Docker?
Docker is an open-source platform that allows developers to develop, deploy, and run applications in containers. Docker provides a simple API that is used to create, start, stop, and remove containers. It also provides advanced features such as network isolation, storage, and image management.
When you build a Docker image, it includes everything required to run your application such as the code, runtime, system tools, and libraries. Docker images can be easily shared and distributed across the internet, making the deployment of applications much simpler.
What is Containerd?
Containerd is a container runtime that is a part of the Docker ecosystem. It is an open-source project started by Docker to provide a lightweight container runtime that can be easily integrated with other container orchestration platforms. Containerd is designed to be fast, reliable, and efficient in managing containers.
Containerd has a modular architecture that allows developers to choose the components they want to use without having to include unnecessary components. It supports a variety of container technologies such as Docker, CRI-O, and rkt.
Docker versus Containerd
Docker Engine and Containerd have different architectures and functionalities that make them suitable for different use cases. Here are some key differences between Docker and Containerd:
Architecture
Docker Engine has a monolithic architecture that includes everything in the Docker platform such as the client, server, and container runtime. This architecture makes Docker Engine a one-stop solution for containerization, as it provides you with all the tools you need to build, deploy and manage containers.
In contrast, Containerd has a modular architecture that separates the components into several layers, each focused on a specific aspect of containerization. This approach allows you to use only the components you need, making Containerd more lightweight and flexible than Docker Engine.
Size
Docker Engine is relatively bulky compared to Containerd. This is because Docker Engine includes several tools and components that may not be required for specific use cases.
In contrast, Containerd is more lightweight because it contains only the essential components required to manage containers. This makes it a suitable choice for low-resource environments.
Compatibility
Docker Engine is compatible with a vast array of tools and technologies. This compatibility has made it the industry standard for containerization, and most container orchestration platforms, including Kubernetes, are designed to work smoothly with Docker Engine.
In contrast, Containerd is still relatively new and has yet to achieve the same level of compatibility as Docker Engine. However, Containerd is gaining popularity, and several container orchestration platforms have already begun to integrate with it.
Conclusion
Docker Engine and Containerd both have their strengths and weaknesses, which should be taken into consideration when choosing the right container runtime for your use case. Docker Engine provides a full-suite containerization solution that is easy to use and compatible with most container orchestration platforms. In contrast, Containerd is more lightweight and flexible, making it a suitable choice for low-resource environments.
When it comes to Kubernetes, both Docker Engine and Containerd are compatible and can be used to run containers on a Kubernetes cluster. However, with Kubernetes, it is recommended to use Containerd because of its lightweight architecture and better integration with the Kubernetes ecosystem. The Kubernetes community is also actively developing and improving Containerd's Kubernetes integration.