Since becoming a Racker back in 2007, one of my all time favorite websites has been slumlordhosting.com. Slumlord Hosting is a parody of really bad shared hosting environments, advertising some amazing features:
On top of the features listed above, the website itself is glorious. Looking at it recently, I began to think to myself, "If I were running a business like this, what could I use to squeeze every possible resource out of a server and offer it up for shared hosting?" Enter Cloud Servers and Docker. My strategy is simple: build a Cloud Server, install Docker, and then create as many containers as possible. I've decided to use WordPress containers since WordPress is extrememly popular.
Docker is a very, VERY popular open source project. Since the project was open sourced only a few months ago, Docker has over 4800 stars, 490 forks, and over 300 watchers on GitHub. There are over 100 contributors. So what does Docker do? From the Docker website:
Docker is an open-source engine that automates the deployment of any application as a lightweight, portable, self-sufficient container that will run virtually anywhere.
Docker containers can encapsulate any payload, and will run consistently on and between virtually any server. The same container that a developer builds and tests on a laptop will run at scale, in production, on VMs, bare-metal servers, OpenStack clusters, public instances, or combinations of the above.
Now that we know what Docker is, let's look at how to implement it for our purposes as a hosting slumlord.
To install Docker, I will need a Rackspace Cloud Server. I'm starting with Ubuntu 13.04 and my SSH key for easy login:
nova boot --image 1bbc5e56-ca2c-40a5-94b8-aa44822c3947 --flavor 2 --key-name mykey slumlord
Notice I am also using the smallest server available: 512M of RAM. This is way too much by slumlord standards, but at least I can have more containers. When the server is up, install Docker:
apt-get update apt-get install linux-image-extra-`uname -r` apt-get install software-properties-common git # Add the Docker repository key to your local keychain curl http://get.docker.io/gpg | apt-key add - # Add the Docker repository to your apt sources list. echo deb https://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list # update apt-get update # install apt-get install lxc-docker
If you want to know more about what you just did, take a look at the Docker documentation. Now that Docker is installed, I need to create a WordPress Docker container.
For this I forked a project on GitHub called "docker-wordpress" written by John Fink. Why fork? To use Ubuntu 13.04 of course! To create a WordPress container, run the following commands:
# Build the container docker build -t slumlord/wordpress git://github.com/hhoover/docker-wordpress.git # Start it up docker run -d slumlord/wordpress # Check your port docker port <container-id> 80
This will build a WordPress docker container and run it. You can browse to your Cloud Server IP address and port that Docker provides to get a WordPress installation page. Let's take a look at the Dockerfile that makes the magic happen:
FROM boxcar/raring MAINTAINER Hart Hoover <firstname.lastname@example.org> RUN apt-get update # DATE Thu Aug 22 10:22:19 EDT 2013 RUN apt-get -y upgrade RUN DEBIAN_FRONTEND=noninteractive RUN apt-get -y install mysql-client mysql-server apache2 libapache2-mod-php5 pwgen python-setuptools vim-tiny php5-mysql openssh-server sudo RUN easy_install supervisor ADD ./start.sh /start.sh ADD ./foreground.sh /etc/apache2/foreground.sh ADD ./supervisord.conf /etc/supervisord.conf RUN echo %sudo ALL=NOPASSWD: ALL >> /etc/sudoers RUN rm -rf /var/www/ ADD http://wordpress.org/latest.tar.gz /wordpress.tar.gz RUN tar xvzf /wordpress.tar.gz RUN mv /wordpress /var/www/ RUN chown -R www-data:www-data /var/www/ RUN chmod 755 /start.sh RUN chmod 755 /etc/apache2/foreground.sh RUN mkdir /var/log/supervisor/ EXPOSE 80 EXPOSE 22 CMD ["/bin/bash", "/start.sh"]
Basically this Dockerfile installs packages we need, puts scripts in place for us, and downloads and unpacks WordPress. The
start.sh script sets up a WordPress MySQL database and generates passwords, while the
foreground.sh script starts Apache. Docker doesn't let you start services using
service some_service start or
/etc/init.d/serviced start, so here we're using supervisord to start services for us. The Dockerfile also makes sure that port 80 is available externally for our web server, and 22 is open so we can SSH to the container. These ports will be connected to a port on the host machine.
You can see a lot of information about the running container with the
docker inspect <container-id>
Now it's time to make this available for customers! Go ahead and kill this docker contatiner. Our application will make more later:
docker stop <container-id>
The Slumlord WordPress dashboard is also a forked project on GitHub. The original project was a proof-of-concept SaaS application for Memcached. We're using it here for our nefarious slumlord purposes. First we need to install dependencies:
apt-get install libxslt-dev libxml2-dev build-essential libpq-dev curl -L https://get.rvm.io | bash -s stable --ruby=1.9.3 source /usr/local/rvm/scripts/rvm
Once you have the dependencies installed, clone the front end repository:
git clone https://github.com/hhoover/slumlord-wordpress /var/www cd /var/www # accept when you see the RVM message bundle install
Then we need to create the database and start the rails server:
rake db:migrate rails server
You can set this application up to run with Unicorn/Passenger/Thin/whatever app server if you like but that setup is outside the scope of this post. Navigate to the IP address of your server on port 3000 and marvel at Slumlord WordPress.
When a user clicks the "Sign Up Now" button and creates an account, a docker container with Apache, PHP, MySQL and WordPress is created from the template container we made earlier.
What if a customer wanted to leave Slumlord WordPress and migrate away? While the probability of this is close to zero, Docker makes it easy:
docker commit <container-id> customer/wordpress
The container in its current state can then be moved to a different server running Docker and started back up. Lucky for the slumlord, if a customer wants to sign up with your service, this helps you as well!