Docker Concepts Recap

Docker Engine is an application that consists of a daemon , an API , and a client :

The Docker daemon is a server that manages the images, containers, networks, and volumes.
The Docker client is the user interface for Docker. The client is a CLI, so most of the work you do with Docker will take place at the command line.

The client communicates with the daemon through the command line API as shown in the image below:

Docker Graphic

Docker engine consists of the Docker Daemon, Docker API, and Docker Client

Docker Concepts Cont.

You will be using the Docker Engine to create and run containers, so if you have not installed Docker using the links above, please be sure to do so.

Additional parts of the Docker platform you will interact with are the Docker are the image , container , and registry .

The Docker Image

A Docker image is the set of instructions for creating a container. The image typically includes a file system and the parameters that will be used for the container.

Custom images for your application can be created using multiple image layers, starting with a standardized parent image . The parent image often contains the file system of a particular operating system, like Ubuntu 18:04. To create the image for your application, you can then add your application files as an additional image layers. You will be able to see this structure more clearly when you create Dockerfiles in the coming classroom concept.

The Docker Container

You have already been introduced to containers, and a Docker container is just the Docker-specific implementation of the concept. In practice, Docker containers are created from Docker images - a container is a runnable instance of an image. Note that since the image is a set of instructions for creating a container, multiple containers can be created from the same image.

Docker Registry

Docker images can be stored and distributed using a Docker registry . In the next classroom concept, you will download and run an image from DockerHub , which is a free registry with many images you can use.

Docker Quizzes

Docker Quiz

SOLUTION:

Docker Registries

Docker Quiz 2

SOLUTION:

Docker Daemon
Docker Client
Docker API

Summary and Further Research

Summary

In this section, you’ve learned about Docker, which is the most common container platform. You’ve also been introduced to concepts related to how Docker works, including the

Docker daemon,
Docker client,
Docker images and containers, and
the Docker Registry.

Further Research

You can read more about general Docker concepts here .