We live in an imperfect world. Despite our best intentions and planning, sometimes things don't turn out the way we had expected. We need to be able to step back and take a look at what went wrong. When we cannot immediately see what is causing the error, we need to be able to reach into a toolbox of techniques to help us discover the problem. This process of figuring out what went wrong and how to fix it is what we call troubleshooting.
In this chapter, we will explore different techniques for troubleshooting NGINX:
Analyzing log files
Configuring advanced logging
Common configuration errors
Operating system limits
Performance problems
Using the Stub Status module