Where does the Docker daemon run?

The Docker daemon runs on the Docker host operating system, which is responsible for managing Docker containers and images. It is a server-side program that handles the creation, running, and monitoring of containers, providing a REST API that can be interacted with using the Docker CLI. By operating directly on the host OS, the daemon can efficiently manage resources such as CPU and memory for the containers it orchestrates.

This placement of the Docker daemon allows it to interact with the system's kernel, creating and managing lightweight containers that share resources while remaining isolated from one another. The daemon also communicates with a Docker client, allowing users to send commands for container management.

In contrast, the other contexts presented—such as running within a container environment or on a Docker registry—do not align with the role or function of the Docker daemon, which is fundamentally tied to the underlying host operating system for its operations. The notion of running outside of the system kernel is also misleading, as the daemon leverages the kernel's services to manage containers effectively.