Docker Workshop

Cool, now lets try a full example. Lets say we have a passenger + ruby and a database webapp.

Passenger/rack/ruby setup

Lets put this Dockerfile into a new folder:

FROM litaio/ruby

RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 561F9B9CAC40B2F7

RUN apt-get install -y apt-transport-https ca-certificates

RUN echo "deb https://oss-binaries.phusionpassenger.com/apt/passenger trusty main" >> /etc/apt/sources.list

RUN apt-get update -qq

RUN apt-get install -y passenger

RUN gem install rack daemon_controller sinatra --no-ri --no-rdoc

WORKDIR /app

EXPOSE 3000
VOLUME ["/app"]

This base image, litaio/ruby already has build out Ruby 2.1.2 for us. You can check out that images Dockerfile here.

You also need to create a file called config.ru in that folder:

run Proc.new {|env| [200, {"Content-Type" => "text/html"}, ["Hello Rack!"]]}

And lets see if it works:

$ docker build -t workshop/full .
...
$ docker run -i -p 3000:3000 -v $(pwd):/app -t workshop/full passenger start

If you don't get any errors, navigate to http://your-ip:3000

Sinatra setup

Sinatra is a nice little webframework with minial configuration. Lets replace our config.ru with:

require 'rubygems'
require './app'
 
run Sinatra::Application

We also need our Sinatra code in app.rb:

require 'sinatra'
 
get '/' do
  "Hello from Sinatra!"
end

$ docker run -i -p 3000:3000 -v $(pwd):/app -t workshop/full passenger start

If you don't get any errors, navigate to http://your-ip:3000

Database setup

Lets start a database:

$ docker run -d --name db -p 3306:3306 -e MYSQL_ROOT_PASSWORD=root orchardup/mysql
...
$ mysql -uroot -h127.0.0.1 -proot

mysql> show databases;
...

The exercises below will have you link the two containers up.

Exercises

• Using ActiveRecord, connect to the database with ruby
• Insert records on /add, list records on /
• Stop and start the web container, does your data still exist?
  • How about the database container?
• Extra: Enable workshop/full to allow docker run -t workshop/full to serve the app.