Surprising Costs of Windows Azure Hosted Services

This summer I had a few days to twiddle my thumbs between quitting my job and starting with my new employer, Unstoppable Software. Creative ideas ran wild inside my head, the time off made me feel like I had an infinite amount of time to make them tangible. I whipped up a few websites and wondered where I could cheaply host them since they were built in ASP.NET MVC. Naturally, the first thing that came to mind was to store them in Windows Azure. After all, my BizSpark benefits included a reasonable amount of free service and I wanted to learn more about how the hosting service worked.

At first, this turned out to be a great idea. I was able to quickly get my site up and running in a Production environment on Windows Azure with a custom domain. Best of all, hosting was free!

Getting a working site in Production ended up being my biggest mistake.

I soon realized that I wanted a second hosting environment so that I could test development changes without affecting the working application in Production. Windows Azure’s easy to use deployment interface suggested the creation of a Staging Environment.

The Staging site worked great. It allowed me to test with a different URL until I was satisfied with the results, then pushing my code to Production. Unfortunately, deploying to a second environment doubled the rate of consumption of a key cost metric, Compute Hours!

A Compute Hour is an hour of application use multiplied by the number of server instances. This is calculated regardless of the state of deployment (Suspended versus Active) and the environment (Production versus Staging). I was very surprised to discover this when I found a charge (below) for Microsoft Online on my credit card statement. Apparently, other developers found out the hard way as well.

I expected the Compute Hours to be accumulated only by my Production environment. I certainly did not expect my billed rate to increase simply by following the best practice of using a Staging environment to test my application, especially if it was suspended when I was not testing. Additionally, I had incorrectly assumed that Compute Hours were only calculated when my web application was processing requests (of which I was not receiving many). I had not really thought about the cost since hosting was free at first. My recommendation to Microsoft is to make it more obvious to developers that the cost doubles when using an additional environment. I would also like to see a long-term Azure strategy for hosting low-traffic sites. Luckily, I found out about the increase in cost without running up a huge bill.