HyperLogLog for Rails and Postgres
Fluentd: Unified Logging Layer (project under CNCF)
Log outgoing HTTP requests in ruby
Log4r is a comprehensive and flexible logging library for use in Ruby programs. It features a heirarchical logging system of any number of levels, custom level names, multiple output destinations per log event, custom formatting, and more.
A flexible logging library for use in Ruby programs based on the design of Java's log4j library.
An attempt to tame Rails' default policy to log everything.
Awesome rails logs
A Ruby structured logging is capable of handling a message, custom data or an exception easily and generates JSON or human readable logs.
Rails Semantic Logger replaces the Rails default logger with Semantic Logger
Simple logging
Semantic Logger is a feature rich logging framework, and replacement for existing Ruby & Rails loggers.
Dead simple Ruby Syslog logger
Yell - Your Extensible Logging Library