What is Docker?

https://docs.docker.com/userguide

Details of Docker

Basics of Docker

Container

Image

Engine

Hub

Previously used LXC

Now uses https://github.com/docker/libcontainer

A container is a self contained execution environment that shares the kernel of the host system and which is (optionally) isolated from other containers in the system.

VM

Docker container

Large

Small

Consume significant CPU and memory

Basically zero memory and CPU overhead

Not easily portable between VM environments

Run in any linux environment

Hardware centric

Application centric

An image is the source of a docker container.

Imperfect analogy:

MyClass.java -> MyClass.class -> running instance of MyClass running in JVM

Dockerfile -> docker image -> docker container

Manages containers

Start/Stop

Status

Linking

etc

https://registry.hub.docker.com

Store ready-made docker images

Getting Started

Not linux so no containers

Boot2Docker to the rescue

https://docs.docker.com/installation/mac

Dockerizing

Manually create

You can create a docker image by just running commands against a base image.

docker pull learn/tutorial
docker run learn/tutorial apt-get install -y ping
docker ps -l
docker commit <id from previous step> learn/ping
docker run learn/ping ping google.com

https://www.docker.com/tryit

Dockerfile

Instead of running commands and saving, can create a Dockerfile that specifies all the commands to build an image.

e.g. Dockerfile for deploying a .war that we have archived in artifactory.

FROM tutum/tomcat

ADD <Artifactory url>/my-app-0.1-SNAPSHOT.war $CATALINA_HOME/webapps/my-app.war

Dockerfile

Build the Dockerfile into an image and tag the image

docker build -t="myname/mytomcatapp:v1" .

Create a container by running the image

docker run -t -i myname/mytomcatapp:v1

Problem

How to spin up multiple containers with one command and get them to talk to each other?

Solution: Vagrant

https://www.vagrantup.com/blog/feature-preview-vagrant-1-6-docker-dev-environments.html

What is Vagrant?

# install homebrew -- for making installation easier
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" 

# install cask -- for making installation easier
brew update
brew tap phinze/homebrew-cask
brew install brew-cask

# Install virtualbox -- need a VM tool
brew cask install virtualbox

# Install vagrant
brew cask install vagrant

Installing Vagrant

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
  config.vm.define "mongo" do |v|
    v.vm.provider "docker" do |d|
      d.vagrant_vagrantfile = "./docker/host-vm/Vagrantfile"
      d.build_dir = "docker/mongo"
      d.ports = ['27017:27017']
      d.name = "mongo"
    end
  end
  
  config.vm.define "my-app" do |v|
    v.vm.provider "docker" do |d|
      d.vagrant_vagrantfile = "./docker/host-vm/Vagrantfile"
      d.build_dir = "."
      d.ports = ['5000:5000']
      d.link("mongo:expected-mongo-host.net")
    end
  end
end

Specify VM to use to host Docker since we are on a Mac

Dockerfile location

Ports to forward

Container name

Linking creates a hosts file entry with the ip of the linked container. Also sets some env variables.

FROM dockerfile/mongodb

Dockerfile for mongo

FROM node:0.10.31-onbuild 

EXPOSE 5000

Dockerfile for nodejs app "my-app"

Dockerfile is placed in root of "my-app"

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|

  config.vm.box = "hashicorp/precise64"
  config.vm.provision "docker"
  config.vm.provision "shell", inline:
      "ps aux | grep 'sshd:' | awk '{print $2}' | xargs kill"

  config.vm.network :forwarded_port, guest: 5000, host: 5000
  config.vm.network :forwarded_port, guest: 27017, host: 27017
end

Vagrantfile for host VM

vagrant up --provider=docker --no-parallel

Now whole environment can be run with one command

Sample App

What's next?

Use containers for production deployments

Improved quality/stability/consistency. Configuration of app stack is versioned and committed.
Less work for techops. Just provision bare linux machine
Faster. Setting up applications in new server is as simple as "docker run"
Reduce costs. Apps run in their own container, so each server could have many apps running in nearly complete isolation.
Fast deployments. Docker uses diff file system for images. Any layers already run are cached.

Docker containers talking to each other across hosts

Potentially create full environments with a single command (production, integration, DR, etc.)
Could create these full environments on cloud commodity hardware.

Still developing space but lots of players (e.g. Google Kubernetes, decking.io, etc)
System should be pretty mature
Can be a problem if you have monolithic dependencies

Challenges

What is Docker?

Details of Docker

Basics of Docker

Getting Started

Dockerizing

Manually create

Dockerfile

Dockerfile

Problem

How to spin up multiple containers with one command and get them to talk to each other?

Solution: Vagrant

What is Vagrant?

Sample App

What's next?

Use containers for production deployments

Docker containers talking to each other across hosts

Other ideas?

Questions?

Docker and Vagrant

Docker and Vagrant

Ryan Walls

What is Docker?

Details of Docker

Basics of Docker

Getting Started

Dockerizing

Manually create

Dockerfile

Dockerfile

Problem

How to spin up multiple containers with one command and get them to talk to each other?

Solution: Vagrant

What is Vagrant?

Sample App

What's next?

Use containers for production deployments

Docker containers talking to each other across hosts

Other ideas?

Questions?

Docker and Vagrant

More from Ryan Walls