Loggly, the online logging management service, has posted a guide that aims to help you get up to speed with logging in PHP starting from the basics out to more recent changes in PHP 7.

This guide explores the basics of logging in PHP, where to find PHP logs, and how these logs help you more effectively troubleshoot problems and monitor your PHP application. There are a couple of different elements you’ll want to consider logging: errors emitted by the PHP engine itself when a core function fails or if code can’t be parsed, custom errors that your application triggers, usually caused by missing or incorrect user input and activities in your application that you may want to analyze at a later time, such as recording when a user account is updated or content in a CMS is updated

They start with a look at the configuration settings you can change to modify how and what your application logs. They also mention run-time configuration changes and the default error log locations (file-based). From there they get into some of the basic, built-in logging functions and the format of the logs they write. The next section talks about application error logs (logs based on failures in PHP itself) and an example of writing logs with JSON instead of plain text. The post ends with a look at exception handling and logging for base, custom and SPL exception types, pointing out the change in PHP 7 around the Throwable interface.