This will be the first in a series of posts where I go through the steps of creating a highly available minimum viable architecture.
To see the results of the step by step guide in video form click hereHigh availability is becoming more and more important. The Internet gives people the opportunity to shop/work and communicate with more flexibility than any other time in human history. Software is expected to work, and it's expected to work 100% of the time. Businesses can not afford to have the negative exposure which a service not being available brings.
I'm using this series of blog posts to increase my knowledge of Amazon Web Services and my Linux administration skills. Although I've had exposure to solving this style of project before, I want to learn and increase my skill set further, whilst sharing knowledge gained with a wider community.
All and any feedback would be greatly appreciated.
For these blog posts I'm going to create the minimum viable architecture using the following stack.
I'll be using Amazon web services to handle the hardware management, and using many of their software products to achieve the highly available architecture.
The rest of the software stack will use Ubuntu, Node.js and Git. I'm using these technologies as they're very popular in the web development world, simple to install and have been designed to work at scale.
Before delving into building the application I took a while to think about the minimum viable architecture needed to produce highly available software stack. I also wanted to design the application in a scalable fashion, taking on advice from other developers and using my own personal experiences.
Amazon Cloudfront and Route 53 are used to speed up delivery of the website, and manage DNS , which from personal experience can be tricky to get to right. I'm more than happy to pass this responsibility off to the team at Amazon.
The next level down will consist of two web servers. These web servers will handle incoming requests, communicate with web services and render the data returned.
Step 1: Create your EC2 instances
Step 2: SSH to one of the machine
On your desktop machine run the following commands
sudo chmod 600 ~/.ssh/ec2-keypairname.pem ssh-add ec2-keypairname.pem ssh -v ubuntu@[PublicDNSOfInstance1]
Step 3: Create a simple node.js application
sudo locale-gen en_GB.UTF-8 sudo apt-get update sudo apt-get install git sudo apt-get install nodejs sudo apt-get install npm sudo mkdir -p /var/www/frontend/ sudo chown -R ubuntu:ubuntu /var/www/frontend/ cd /var/www/frontend/ npm install express ./node_modules/express/bin/express //Press y to destination is not empty, continue? npm install //Unable to open port 80 directly, use iptables to redirect port 80 traffic to port 3000 sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 3000 node app &At this point you should be able to navigate to the public DNS entry in browser and see your node app running.
Step 4: Create an upstart script for the application
mkdir /var/www/frontend/log/ sudo vi /etc/init/nodefrontendapp.conf
And paste in the following the following
description "node.js front end server"
author "kvz"
start on startup
stop on shutdown
script
export HOME="/root"
exec /usr/bin/node /var/www/frontend/app.js 2>&1 >> /var/www/frontend/log/node.log
end script
Save and exit vi and run the following commands
sudo chmod u+x /etc/init/nodefrontendapp.conf sudo start nodefrontendapp
Step 5: Set up a cloned server
git init . git add . git commit -m "Inital Commit" ssh-keygen -t dsa //use default directory cd ~/.ssh/ cat id_dsa.pub >> authorized_keys //keep default options exit
On your desktop machine copy the ssh key to the other instance via ssh
scp ubuntu@[PublicDNSOfInstance1:/home/ubuntu/.ssh/id_dsa . scp id_dsa ubuntu@[PublicDNSOfInstance2]:/home/ubuntu/.ssh/id_dsa
Now we'll clone our basic application onto the second web server
ssh ubuntu@[PublicDNSOfInstance2] sudo locale-gen en_GB.UTF-8 sudo apt-get update sudo apt-get install git sudo apt-get install nodejs sudo apt-get install npm sudo mkdir -p /var/www/frontend/ sudo chown -R ubuntu:ubuntu /var/www/frontend/ cd /var/www/frontend/ git clone ubuntu@[IpAddresOfInstance1]:/var/www/frontend/. sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 3000Create the upstart script as mentioned in Step 4 for this server too.
Now the simple node applications are up and running on two seperate servers, the last part is getting them to work under out domain name.
Step 6: Setting up Route 53