This is a quick tutorial to deploy a web service (a social network) by the LNMP (Linux, Nginx, MongoDB, Python) infrastructure on any IaaS cloud. The repo at Github is at https://github.com/dapangmao/minitwit-mongo-ubuntu.

Stack

The stack is built on the tools in the ecosystem of Python below.

Tool	Name	Advantage
Cloud	DigitalOcean	Cheap but fast
Server distro	Ubuntu 14.10 x64	Everything is latest
WSGI proxy	Gunicorn	Manage workers automatically
Web proxy	Nginx	Fast and easy to configure
Framework	Flask	Single file approach for MVC
Data store	MongoDB	No scheme needed and scalable
DevOps	Fabric	Agentless and Pythonic

In addition, a Supervisor running on the server provides a daemon to protect the Gunicorn-Flask process.

The MiniTwit app

The MiniTwit application is an example provided by Flask, which is a prototype of Twitter like multiple-user social network. The original application depends on SQLite. However, the data store could be modified to fit the category of NoSQL such as Google Data Store or MongoDB. A live MintiTwit demo is hosted at http://minitwit-123.appspot.com/public

Deployment

1. Install Fabric and clone the Github repo

The DevOps tool is fabric that is simply based on SSH. The fabfile.py and the staging flask files are stored on Github. We should install fabric and download the fabfile.py on the local machine before the deployment.

sudo pip install fabric 
wget https://raw.githubusercontent.com/dapangmao/minitwit-mongo-ubuntu/master/fabfile.py
fab -l

2. Input IP from the virtual machine

A new VM usually emails IP address and the root password. Then we could modify the head part of the fabfile.py accordingly. There are quite a few cheaper cloud provider for prototyping other than Amazon EC2. For example, a minimal instance from DigitalOcean only costs five dollars a month. If SSH key has been uploaded, the password could be ignored.

env.hosts = ['YOUR IP ADDRESS'] # <--------- Enter the IP address
env.user = 'root'
env.password = 'YOUR PASSWORD'  # <--------- Enter the root password

3. Fire up Fabric

Now it is time to formally deploy the application. With the command below, the fabric will first install pip, git, nginx, gunicorn, supervisor and the latest MongodB, and configure them sequentially. In less than 5 minutes, a Flask and MongoDB application will be ready for use. Since DigitalOcean has its own software repository for Ubuntu, and its VMs are on SSD, the deployment is even faster, which is usually finished in one minute.

fab deploy_minitwit