Book Image

Nginx Troubleshooting

By : Alexey Kapranov
Book Image

Nginx Troubleshooting

By: Alexey Kapranov

Overview of this book

Nginx is clearly winning the race to be the dominant software to power modern websites. It is fast and open source, maintained with passion by a brilliant team. This book will help you maintain your Nginx instances in a healthy and predictable state. It will lead you through all the types of problems you might encounter as a web administrator, with a special focus on performance and migration from older software. You will learn how to write good configuration files and will get good insights into Nginx logs. It will provide you solutions to problems such as missing or broken functionality and also show you how to tackle performance issues with the Nginx server. A special chapter is devoted to the art of prevention, that is, monitoring and alerting services you may use to detect problems before they manifest themselves on a big scale. The books ends with a reference to error and warning messages Nginx could emit to help you during incident investigations.
Table of Contents (15 chapters)
Nginx Troubleshooting
About the Author
About the Reviewers
Rare Nginx Error Messages

Configuring Nginx logging

There are two types of logs that Nginx may write. One could also say that there are infinite types because of the log_format directive that allows you to create your own types of logs.

To refresh your memory about what directives are used to configure Nginx logging, here they are:

  • The error_log directive configures the logging of exceptional events that the developers of Nginx consider worth noting. Usually, this is all kinds of errors.

    The format of the directive is this:

    error_log <destination> <log level>;


    The first parameter is usually a path to the file with the log. Recent versions of Nginx starting with 1.7.1 also support logging via syslog, to a local or remote syslog server. There is also a rarely used misnamed special value stderr, which, by the way, does not redirect logging to stderr (the third standard stdio stream or &2 in shell terms) because it does not make much sense to log to stderr from a daemon—daemonization involves closing all...