Yell - Your Extensible Logging Library
Yell works and is tested with ruby 1.8.7, 1.9.x, jruby 1.8 and 1.9 mode, rubinius 1.8 and 1.9 as well as ree.
Installation
System wide:
gem install yell
Or in your Gemfile:
gem "yell"
Usage
On the basics, Yell works just like any other logging library. However, it tries to make your log mesages more readable. By default, it will format the given message as follows:
logger = Yell.new STDOUT
logger.info "Hello World"
#=> "2012-02-29T09:30:00+01:00 [ INFO] 65784 : Hello World"
# ^ ^ ^ ^
# ISO8601 Timestamp Level Pid Message
When no arguments are given, Yell will check for ENV['RACK_ENV']
and
determine the filename from that.
Alternatively, you may define ENV['YELL_ENV']
to set the filename. If neither
YELL_ENV
or RACK_ENV
is defined, 'development' will be the default. Also, if a
log
directory exists, Yell will place the file there (only if you have not passed
a filename explicitly.
Naturally, you can pass a :filename
to Yell:
logger = Yell.new "yell.log"
Levels
Just like any other logging library, Yell allows you to define from which level onwarns you want to write your log message. here are some examples to show how you can combine those.
Example: Write from :info
onwards
logger = Yell.new STDOUT, :level => :info # write on :info, :warn, :error, :fatal
Example: Write on :info
and :error
only
logger - Yell.new STDOUT, :level => [:info, :error] # write on :info and :error only
Example: Write between :info and :error
logger = Yell.new STDOUT, :level => (:info..:error)
# NOTE: The Range might only work with 1.9 compatible rubies!
There are more ways to set your logging level, please consult the wiki on that.
Adapters
Yell comes with various adapters already build-in. Those are the mainly IO-based adapters for every day use. There are additional ones available as separate gems. Please consult the wiki on that - they are listed there.
The standard adapters are:
:stdout
: Messages will be written to STDOUT
:stderr
: Messages will be written to STDERR
:file
: Messages will be written to a file
:datefile
: Messages will be written to a timestamped file
Here are some short examples on how to combine them:
Example: Notice messages go into STDOUT
and error messages into STDERR
logger = Yell.new do
adapter STDOUT, :level => [:debug, :info, :warn]
adapter STDERR, :level => [:error, :fatal]
end
Example: Notice messages to into application.log
and error messages into error.log
logger = Yell.new do
adapter :file, 'application.log', :level => [:debug, :info, :warn]
adapter :file, 'error.log', :level => [:error, :fatal]
end
Example: Every log severity is handled by a separate adapter and we ignore :debug
and :info
levels
logger = Yell.new do
level :warn # only start logging from :warn upwards
adapter :stdout, :level => [:warn]
adapter :datefile, 'error.log', :level => [:error]
adapter :datefile, 'fatal.log', :level => [:fatal]
end
Further Readings
How To: Setting The Log Level
How To: Formatting Log Messages
How To: Using Adapters
How To: The Datefile Adapter
How To: Different Adapters for Different Log Levels
You can find further examples and additional adapters in the wiki. or have a look into the examples folder.
Copyright © 2011-2012 Rudolf Schmidt, released under the MIT license