StreamLogger

StreamLogger is a lightweight library that logs to any stream, like stdout.

Logging to a stream is much more powerful than logging to a file.

How to use

require "stream_logger"

logger = StreamLogger.new(STDOUT)
logger.level = :debug   # Default is :info

logger.debug "It works!"

Simple enough! Let's look at a more interesting example.

How to logify

The logify! command is great for rake tasks and background daemons.

It lets you access the logger from any class or module

and

it automatically logs statements like puts and print.

require "stream_logger"

StreamLogger.logify!

# Note: You do not need to set logger.
logger.warn "This is pretty awesome"

puts "This gets logged, too"

To revert back to normal, use:

StreamLogger.unlogify!

How to change the format

The default format looks like:

2011-09-20T02:43:43-0700  INFO : I'm informative
2011-09-20T02:43:44-0700  WARN : You've been warned
2011-09-20T02:43:44-0700 ERROR : Oh no!

You can change the format with:

logger.format do |level, message|
  "%s %s %s %5s : %s" % [$0, Process.pid, Time.now, level, message]
end

For your convenience, StreamLogger comes with the syslog format.

logger.format = StreamLogger::SYSLOG_FORMAT

How to turn logging off

To turn logging off, use:

logger.level = :off

How to improve the performance of slow log messages

If you have logging code that takes a while to run, you can defer execution. The code below won't execute unless logger.level = :debug. This can save a lot of time in a production environment when the log level is set lower.

logger.debug { sleep(5); "This code takes a while to run" }

Note: This is only faster for slow log messages. In most cases, use the regular method.

How to direct output

Let's assume your program is executed with the command mydaemon and logs to stdout.

stdout

mydaemon

file

mydaemon >> log/mydaemon.log

stdout and file

mydaemon | tee -a log/mydaemon.log

syslog

mydaemon | logger

tcp port

mydaemon > /dev/tcp/127.0.0.1/8000

udp port

mydaemon > /dev/udp/127.0.0.1/514