Summary

Problems surface on a number of levels when bringing a new piece of software into production. Some errors can be tested for and eradicated in a test environment; others surface only under real load with real users. To discover the reasons for these problems, NGINX provides very detailed logging at a number of levels. Some of the messages may have multiple interpretations, but the overall pattern is understandable. By experimenting with the configuration and seeing what kinds of error message are produced, we can gain a feeling for how to interpret the entries in the error log. The operating system has an influence on how NGINX runs, as it imposes certain limits due to default settings for a multiuser system. Understanding what is going on at the TCP level will help when tuning these parameters to meet the load under real conditions. Rounding off our tour of troubleshooting, we saw what kind of information the stub_status module was capable of delivering. This data can be useful...