Per Origin Host Header Override
Load Balancing as a concept is pretty straightforward. Take an existing infrastructure and route requests to the available origin servers so no single server is overwhelmed. Add in some health monitoring to ensure each server has a heartbeat/pulse so proactive decisions can be made. With two steps, you get more effective utilization of your existing resources… simple enough!
As your application grows, however, load balancing becomes more complicated. An example of this — and the subject of this blog post — is how load balancing interacts with the Host header in an HTTP request.
Host headers and load balancing
Every request to a website contains a unique piece of identifying information called the Host header. The Host header helps route each request to the correct origin server so the end user is sent the information they requested from the start.
For example, say that you enter example.com into my URL bar in my browser. You are sending a request to ‘example.com’ to send you back the homepage located within that application. To make sure you actually get resources from example.com, your browser includes a Host header of example.com. When that request reaches the back-end infrastructure, Continue reading
