Introduce to

Outline

What is docker?

Why docker?

Dockerfile

What is docker?

An open platform for developing, shipping, and running applications

What it want to solve?

The matrix from hell

“You've got all types of servers, all types of different languages and frameworks, and all types of application versions to try and maintain across those platforms” - Ben Golub, CEO of Docker

The matrix from hell

We need a container

The matrix from hell

The matrix from hell

Installation

From ubuntu mainstream

Docker goes into Ubuntu mainstream since 14.04

Currently, v0.9

apt-get install docker.io

From Official Repo

The latest version: v1.0

echo deb https://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list

apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9

apt-get update

apt-get install lxc-docker

Why Docker?

Fast and less overhead

Image versioning

Portable

Fast and less overhead

VM v.s. Docker

VM v.s. Docker

Server

Host OS

VM v.s. Docker

Server

Host OS

Hypervisor

VM v.s. Docker

Server

Host OS

VM VM

Hypervisor

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Docker Engine

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

Image1

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

Image1

Image2

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

Image1

App1

Image2

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

Image1

App1

Image2

App2

VM v.s. Docker

Server

Host OS

VM VM

Guest OS

Hypervisor

Dep.

App

Server

Host OS

Container Container

Docker Engine

Image1

App1

Image2

App2

App3

Live Demo

IP: 10.10.100.108

Username: test

Password: 123456

docker pull

Download image from Docker Hub

docker pull [image]

Ex: docker pull debian

docker run (1)

docker run [image] [command]

-i interactive mode

-t pseudo-tty

Ex: docker -i -t run debian /bin/bash

Image versioning

Image v.s. Container

Base on LXC and AUFS

Images are read-only

Read / write on container

Files in container won’t keep unless you commit

Image v.s. Container

Base on LXC and AUFS

Images are read-only

Read and write on container

Files in container won’t keep unless you commit

Image v.s. Container

docker pull debian

Image v.s. Container

docker pull debian

docker run debian /bin/bash

docker commit

docker commit [Container ID] [image name]

docker commit 1c1f5 new_image

Image v.s. Container

docker pull debian

docker run debian /bin/bash

Image v.s. Container

docker pull debian

docker commitdocker commit

docker run debian /bin/bash

Image v.s. Container

docker pull debian

docker commitdocker commit

docker run debian /bin/bash

Portable

Runs on all major Linux distributions

Boot2docker for Mac and Windows users

A ~25 MB tiny VM inside

Ship your container

There are three ways to ship your container:

Docker Hub (docker push)

docker save

docker export

docker save / load

This packing will preserve the history of a docker

docker save [Image Name] > [Archive Name]

docker load < [Archive Name]

docker export / import

This way only keep the difference

docker export [Container ID] > [Archive Name]

cat [Archive Name] | docker import - [Image Name[:Tag]]

Separation of Data and App

docker run (2)

-v [host directory]:[container directory]Bind mount a volume

-p [host port]:[container port]Publish a container's port to the host

Other useful command

docker ps

docker images

docker kill

docker rm

docker rmi

docker logs

docker inspect

Dockerfile

Syntax

FROM

RUN

ENV

ADD

VOLUME

EXPOSE

CMD

Example

docker build

docker build -t [Image Name[:Tag]]\<path to Dockerfile>

docker build -t my_image:v1 .

Build once, run anywhere

Examples

My Concern

Easy to setup over a VM

Separate data and application

Reproduce my environment fast

Jenkins

Initialize shared volume before service start

Use supervisor to manage multiple services

One-time script

Can not use upstart

Use supervisor

Summarize

Do one thing at a time

Treat a docker container as an app

Ecosystem

CoreOS - Work with SystemD

Openstack - An instance type

Docker Hub (Docker Index)

Many providers- Digital Ocean, EC2, Linode, Google Cloud Platform

Gotcha

Don’t have its /sbin/init (Issue 1024)

Share kernel, can not run different Linux Kernel at a time

Use --privileged if needed

Not mentioned

Link to another container

Use share volume on another container

Q & A