Docker

Overview

Open platform for developer and system admins

• to build and test cloud application

• client-server system

• supports multiple cloud platforms

  • AWS, Digital Ocean, etc.

Daemon

CLI Reference

docker image

docker image ls/docker image list/docker images

• shows all top level images
  • their repo and tags, and their size

NOTE: Untagged (dangling) images are also hidden by default

• use the `-a` `–all` flag to show intermediate layers and dangling images

`SIZE` is the cumulative space taken up by the image and all its parent images

• this is also disk space used by the contents of the Tar file
  • created when you `docker save` an image

An image will be listed more than once if it has multiple repository names or tags

• this single image identifiable by its matching `IMAGE ID`
  • uses up the size `SIZE` listed only once

Dockerfile

Add local or remote files and directories: ADD

Use build-time variables: ARG

Specify default commands: CMD

Copy files and directories: COPY

Specify default executable: ENTRYPOINT

Set environment variables: ENV

Which ports your application is listenting on: EXPOSE

Create a new build stage from a base image: FROM

Check a container's health on startup: HEALTHCHECK

Add metadata to an image: LABEL

Specify the author of an image: MAINTAINER

Specify instructions for when the image is used in a build: ONBUILD

Execute build commands: RUN

Set the default shell of an image: SHELL

Specify the system call signal for exiting a container: STOPSIGNAL

Set user and group ID: USER

Create volume mounts: VOLUME

Change working directory: WORKDIR

Docker Engine

Docker Images

Docker Registries