U::Log - a different take on logging

Build Status

An oppinionated logging library.

  • Log everything in development AND production.
  • Logs should be easy to read, grep and parse.
  • Logging something should never fail.
  • Let the system handle the storage. Write to syslog or STDERR.
  • No log levels necessary. Just log whatever you want.

STATUS: ALPHA

Doc is still scarce so it's quite hard to get started. I think reading the lib/u-log.rb should give a good idea of the capabilities.

It would be nice to expose a method that resolves a context into a hash. It's useful to share the context with other tools like an error reporter. Btw, Sentry/Raven is great.

Quick intro

require 'u-log'

# Setups the outputs. IO and Syslog are supported.
l = U::Log.new($stderr, Lines,
  at:  ->{ Time.now.utc },
  pid: ->{ Process.pid },
)

# First example
l.log(foo: 'bar') # logs: at=2013-07-14T14:19:28Z foo=bar

# If not a hash, the argument is transformed. A second argument is accepted as
# a hash
l.log("Hey", count: 3) # logs: at=2013-07-14T14:19:28Z msg=Hey count=3

# You can also keep a context
class MyClass < ActiveRecord::Base
  attr_reader :lines
  def initialize(logger)
    @logger = logger.context(my_class_id: self.id)
  end

  def do_something
    logger.log("Something happened")
    # logs: at=2013-07-14T14:19:28Z msg='Something happeend' my_class_id: 2324
  end
end

Features

  • Simple to use
  • Thread safe (if the IO#write is)
  • Designed to not raise exceptions (unless it's an IO issue)
  • A backward-compatible Logger is provided in case you want to retrofit
  • require "u-log/active_record" for sane ActiveRecord logs
  • "u-log/rack_logger" is a logging middleware for Rack

Known issues

Syslog seems to truncate lines longer than 2056 chars and Lines makes if very easy to put too much data.

Lines logging speed is reasonable but it could be faster. It writes at around 5000 lines per second to Syslog on my machine.

Inspired by

TODO

Error reporting

Create message context

Because the log context is hierarchical,