Confession

Turn off your debug output when deploying to production

What’s the background?

I was developing web applications in the era before cloud servers. I would develop code and hand it over to another team who would do a little testing before deploying it to the live system.

What happened?

I had developed some new code. During this process I wrote a few of my own tests, but also added some debug print statements. These print statements saved their output into a logfile. I got the application to a point where I was pretty sure everything was working and I handed it over to be deployed.

A few weeks later I got a call a few weeks later saying that the app has crashed the server. My initial reaction was denial, it couldn’t possibly be my app which was causing this. But I had forgotten to turn off the debugging print statements and my app had created a large logfile, run the server out of disk space and caused it to crash.

What did I learn?

• Turn off your debugging print statements before going into production.
• Get somebody else to stress test your code before deploying it.
• If you receive code from somebody else to deploy, stress test it first.