sirupsen/logrus

Logrus is a logging library for Go (a programming language commonly used for backend services). Its main purpose is to make log messages more useful by adding structured data to them, instead of just writing a plain text message like "something failed," you attach labeled fields such as the user ID, the action being attempted, and the error code. This makes logs far easier to search and analyze later. It works by replacing Go's built-in logger with a drop-in alternative that supports log levels (debug, info, warning, error, fatal), colored output in the terminal during development, and JSON-formatted output in production, which is the format preferred by log aggregation tools like Logstash or Splunk. Plugins called "hooks" let you route logs to external services or additional outputs. You would use Logrus when building a Go backend service that needs production-quality logging, for example, tracking which user triggered a bug, how long a database query took, or which server processed a request. It's popular in Go codebases because it requires minimal changes to adopt. Note that Logrus is now in maintenance mode, meaning only security and bug fixes are accepted, new Go projects may prefer newer alternatives like Zerolog or Zap.