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DevOps & Automation · Intermediate

Docker Engine

The client-server application consisting of the dockerd daemon, a REST API, and the docker CLI that builds and runs containers.

Definition

The CLI talks to dockerd via the Docker API over a Unix socket (/var/run/docker.sock) or TCP. dockerd delegates container lifecycle to containerd and runc. Access to the Docker socket is effectively root on the host.

Example

systemctl status docker shows the dockerd service.

Exam tip

Mounting /var/run/docker.sock into a container grants host-level control; treat it as a security risk.

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