Docker vs NGINX Unit: What are the differences?

1. Architecture: The key difference between Docker and NGINX Unit lies in their architecture. Docker follows a client-server architecture where a Docker client interacts with a Docker daemon running on the host machine. On the other hand, NGINX Unit is designed as a single binary with minimal dependencies, acting as both the runtime and web server, eliminating the need for a separate daemon or server.
2. Containerization: Docker primarily focuses on containerization, allowing users to package applications along with their dependencies into isolated containers. These containers can then be deployed and run on any system that supports Docker. Conversely, NGINX Unit is more flexible as it supports both containerized and non-containerized applications, allowing developers to deploy different types of workloads with ease.
3. Configuration: Docker uses a declarative approach to configure containers, where users define configuration files called Dockerfiles to build images and containerize applications. NGINX Unit, however, provides a dynamic and declarative configuration model, allowing developers to customize the runtime behavior and manage applications using a flexible JSON-based API, enabling real-time updates without restarting the server.
4. Supported Languages: Docker supports a wide range of programming languages and frameworks, allowing developers to build and run applications in different environments. NGINX Unit, on the other hand, has native support for multiple languages and runtimes, including PHP, Python, Go, and Ruby, making it easier to deploy and manage applications written in these languages without additional configuration.
5. Event-Driven Model: NGINX Unit employs an event-driven model, which enables it to handle a large number of concurrent connections efficiently. This makes it suitable for applications that require high performance and scalability, such as real-time communication or streaming applications. Docker, however, does not provide the same level of fine-grained control over event handling, as it focuses more on isolating and managing containers rather than optimizing for high-performance workloads.
6. Community and Ecosystem: Docker has a vast and active community, along with a rich ecosystem of pre-built container images and tools, making it easier for developers to find support and resources for their projects. NGINX Unit, being a newer technology, has a smaller community and ecosystem but is continuously growing, supported by NGINX, a well-established web server and load balancer.

In summary, Docker and NGINX Unit differ in their architecture, containerization approach, configuration models, supported languages, event-driven capabilities, and community/ecosystem size.