One of the main parts of the docker ecosystem is the Docker Engine.

Docker engine

Consists of:

Docker CLI <===> API <===> Docker Daemon
  • It has an underlying client server architecture that communicates through a REST API.
  • Thus the client the docker CLI talks to the docker daemon using the API
  • Docker CLI is easy with using built,run,ps and other commands.

You can have other clients working with the daemon apart form the CLI,you can build your own client or use a web interface to manage/control the objects.

Thus the docker engine API can be levereged to build complex operations like:

  • Automated schedules operations
  • use docker sdks for python or go and write programs to do with the cli and perform operations
  • docker client can talk with more than daemon

The docker daemon does a lot of things:

  • managing docker objects
  • responding to client requests
  • etc. and doing all the work in the server.

Server is a daemon process and which listens for API requests and is responsible for creating and managing containers,images,n/w’s and other docker objects.

Docker engine is the the system as a whole.

Docker is a set of tools where dockerd is the docker daemon responsible for the many cool stuff offered by docker and does a lot of tasks.

It does:

  • container management

    • Managing the container lifecycle

  • image management

    • Pulling images from registries and managing them locally

  • storage management

    • Metadtata storage.

  • It does all this without client intervention.

  • It also talks to other components that do low level work i.e,containerd

runc is responsible for container low level management.

The docker daemon also has a Plugin architecture and gives docker an extemsible nature where features not provided by docker can be added on as a plugin. Also has other componenets for logging networking etc,and this is a community edition.

The enterprise edition comes with a lot more features.

  • deployement
  • orchestration
  • registry management

Registry

Registry is a storage/content delivery system acting as a hub for the docker images. Every dockerhost has a local registry where it keeps the images,metadata and manages them.

Managing custom registeries is done via the docker registery command available in docker enterprise edition.

Docker pull and push are used to manage registeries and images and can also make private registeries in the docker hub.

docker pull node

Dockerfile

FROM node:alpine

COPY index.js .

CMD ["node","index.js"]

docker run --network host super-server