When you want to run your web application on more than one EC2 instance for scaling and redundancy purposes, you will probably require some form of load balancer to distribute incoming requests evenly across the instances. There are various possible solutions for this.
One option is to launch another EC2 instance and install a load balancer on it yourself. There are quite a few open source load balancing options, though I would tend to recommend HAProxy as it’s fast, efficient, secure, and very flexible. This option involves setting up your Linux instance and installing the software you need yourself, then configuring your chosen load balancer and installing your SSL certificates, etc. Additionally you would need to estimate the necessary instance size to run the load balancing software without getting overloaded and slowing the site down (bearing in mind that SSL termination can be particularly CPU-intensive), then monitoring it accordingly.
Unless there’s a particular reason to take the approach of installing a load balancer on an EC2 instance, a simpler and more effective option – especially for companies taking their first steps into scaling multiple instances for their application – is likely to be Amazon’s own ELB (Elastic Load Balancer). This doesn’t require an EC2 instance with Linux setup, software installation and configuration, etc. It provides a simple interface with easy SSL termination and it will scale itself automatically as needed, so there is little required in the way of planning and monitoring.Continue reading “How to choose and set up a load balancer in AWS”