Docker Image Architecture

Docker is the world’s most popular container engine, so we will focus our discussion of container image architecture on Docker.

A Docker image is a collection of files, including binaries, source code and other dependencies, needed to deploy a container environment. In Docker, there are two ways to create an images:

• Create an image from an existing container - you can run a container from an existing image, modify the container environment, and save the result as a new image.

• Dockerfile - Docker provides a simple, human-readable configuration file that specifies what a Docker image should contain.

$ docker image ls

REPOSITORY                  TAG            IMAGE ID       CREATED         SIZE
alpine/git                  latest         620bef75a214   4 days ago      39.4MB
node                        alpine         515db77e67c7   8 days ago      174MB
ansible                     latest         d174f0236d75   12 days ago     1.36GB
ubuntu                      latest         27941809078c   2 weeks ago     77.8MB