Docker's architecture

As specified on Docker documentation, Docker architecture uses client-server architecture. As shown in the following figure (sourced from Docker's website: https://docs.docker.com/engine/docker-overview/), the Docker client is primarily a user interface that is used by an end user; clients communicate back and forth with a Docker daemon. The Docker daemon does the heavy lifting of the building, running, and distributing of your Docker containers. The Docker client and the daemon can run on the same system or different machines.

The Docker client and daemon communicate via sockets or through a RESTful API. Docker registers are public or private Docker image repositories from which you upload or download images, for example, Docker Hub (hub.docker.com) is a public Docker registry.

Docker's architecture

The primary components of Docker are:

• Docker image: A Docker image is a read-only template. For example, an image could contain an Ubuntu operating system with Apache web server and your web application installed. Docker images are a build component of Docker and images are used to create Docker containers. Docker provides a simple way to build new images or update existing images. You can also use images created by others and/or extend them.
• Docker container: A Docker container is created from a Docker image. Docker works so that the container can only see its own processes, and have its own filesystem layered onto a host filesystem and a networking stack, which pipes to the host-networking stack. Docker Containers can be run, started, stopped, moved, or deleted.