Docker

Docker packages an application and its dependencies into an image and runs it as an isolated container. The same image runs on a laptop, in a CI pipeline and in production on ECS, Fargate or EKS.

Key concepts #

• Docker Engine: the daemon (dockerd) that builds images and runs containers through containerd and runc.
• Docker CLI: the docker command, a client that talks to the daemon.
• Image: a read-only stack of layers with the application and its metadata. See Docker basics.
• Container: a running instance of an image, a Linux process isolated with namespaces and cgroups.
• Registry: where images are stored and shared: Docker Hub, Amazon ECR and others.
• Dockerfile and Compose: the files that describe how to build an image and how to run several containers together.

On macOS and Windows, Docker needs a Linux VM. Rancher Desktop and Docker Desktop provide it.

Learn it #

The series Docker and Rancher Desktop goes from the first container to Compose, BuildKit, image security and a local Kubernetes cluster.