**Logging** is a flexible logging library for use in Ruby programs based on the design of Java's log4j library. It features a hierarchical logging system, custom level names, multiple output destinations per log event, custom formatting, and more.

See also: http://logging.apache.org/log4j

Fluentd is an open source data collector designed to scale and simplify log management. It can collect, process and ship many kinds of data in near real-time.

Tame Rails' multi-line logging into a single line per request

A gem that provides a client interface for the Sentry error logger

This is an experiment to try and make logging more flexible and more consumable. Plain text logs are bullshit, let's emit structured and contextual logs. Metrics, too!

Library to send GELF messages to Graylog logging server. Supports plain-text, GELF messages and exceptions via UDP and TCP.

Yell - Your Extensible Logging Library. Define multiple adapters, various log level combinations or message formatting options like you've never done before

Feature rich logging framework, and replacement for existing Ruby & Rails loggers.

Log outgoing HTTP requests made from your application. Helpful for tracking API calls of third party gems that don't provide their own log output.

MongoDB logger for Rails

A Railtie for for integrating the [Logging](https://github.com/TwP/logging) framework into your Rails 3 application.

Lumber tries to make it easy to use the more robust log4r logging system within your rails application. To do this it sets up log4r configuration from a yml file, and provides utility methods for adding a :logger accessor to classes dynamicaly as they get created.

A structured logging system is capable of handling a message, custom data or an exception easily. It has JSON formatters compatible with Bunyan or pino for Node.js and human readable formatter with Awesome Print for console.

clogger is Rack middleware for logging HTTP requests. The log format is customizable so you can specify exactly which fields to log.

A Rails engine which receives logs and provides an interface for them

Wraps logging in a nice and convenient way making it easy to apply on any project

Navigating noise in your log files can be like trying to cross a busy road and avoid the cars. Frogger makes your log files more fun by adding some good ol' 8 bit color and a bit of formatting.

Logging library that provides the ability to add class/module specific filters

Hybrid action logging, consisting of standard and custom logging.

Captures raketask output along with additional information (task name, duration, start time, error) for further usage.

The official justlogging.com gem