Yell

Yell - Your Extensible Logging Library is a comprehensive logging replacement for Ruby.

Yell works and is tested with ruby 1.8.7, 1.9.x, 2.0.0, jruby 1.8 and 1.9 mode, rubinius 1.8 and 1.9 as well as ree.

If you want to conveniently use Yell with Rails, then head over to yell-rails. You’ll find all the documentation in this repository, though.

Installation

System wide:

“nsole gem install yell

“

Or in your Gemfile:

“by gem “yell”

“

Usage

On the basics, you can use Yell just like any other logging library with a more sophisticated message formatter.

“by logger = Yell.new STDOUT

logger.info “Hello World”

=> “2012-02-29T09:30:00+01:00 [INFO] 65784 : Hello World”

^ ^ ^ ^

ISO8601 Timestamp Level Pid Message

“

The strength of Yell, however, comes when using multiple adapters. The already built-in ones are IO-based and require no further configuration. Also, 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`

“by logger = Yell.new do |l| l.adapter STDOUT, level: [:debug, :info, :warn] l.adapter STDERR, level: [:error, :fatal] end

“

Example: Typical production Logger

We setup a logger that starts passing messages at the :info level. Severities below :error go into the ‘production.log’, whereas anything higher is written into the ‘error.log’.

“by logger = Yell.new do |l| l.level = ‘gte.info’ # will only pass :info and above to the adapters

l.adapter :datefile, ‘production.log’, level: ‘lte.warn’ # anything lower or equal to :warn l.adapter :datefile, ‘error.log’, level: ‘gte.error’ # anything greater or equal to :error end

“

Example: Typical production Logger for Heroku

When deploying to Heroku, the “rails_log_stdout” gem gets injected to your Rails project. Yell does not need that when properly configured (see yell-rails for a more convenient integration with Rails).

“by logger = Yell.new do |l| l.level = ‘gte.info’

l.adapter :stdout, level: ‘lte.warn’ l.adapter :stderr, level: ‘gte.error’ end

“

But I’m used to Log4r and I don’t want to move on

One of the really nice features of Log4r is its repository. The following example is taken from the official Log4r documentation.

“by require ‘log4r’ include Log4r

create a logger named ‘mylog’ that logs to stdout

mylog = Logger.new ‘mylog’ mylog.outputters = Outputter.stdout

later in the code, you can get the logger back

Logger[mylog]

“

With Yell you can do the same thing with less:

“by require ‘yell’

create a logger named ‘mylog’ that logs to stdout

Yell.new :stdout, name: ‘mylog’

later in the code, you can get the logger back

Yell[mylog]

“

There is no need to define outputters separately and you don’t have to taint you global namespace with Yell’s subclasses.

Adding a logger to an existing class

Yell comes with a simple module: +Yell::Loggable+. Simply include this in a class and you are good to go.

“by

Before you can use it, you will need to define a logger and

provide it with the `:name` of your class.

Yell.new :stdout, name: ‘Foo’

class Foo include Yell::Loggable end

Now you can log

Foo.logger.info “Hello World” Foo.new.logger.info “Hello World”

“

It even works with class inheritance:

“by

Given the above example, we inherit from Foo

class Bar < Foo end

The logger will fallback to the Foo superclass

Bar.logger.info “Hello World” Bar.new.logger.info “Hello World”

“

Adding a logger to all classes at once (global logger)

Derived from the example above, simply do the following.

“by

Define a logger and pass `Object` as name. Internally, Yell adds this

logger to the repository where you can access it later on.

Yell.new :stdout, name: Object

Enable logging for the class that (almost) every Ruby class inherits from

Object.send :include, Yell::Loggable

now you are good to go… from wherever you are

logger.info “Hello from anything” Integer.logger.info “Hello from Integer”

“

Suppress log messages with silencers

In case you woul like to suppress certain log messages, you may define silencers with Yell. Use this to get control of a noisy log environment. For instance, you can suppress logging messages that contain secure information or more simply, to skip information about serving your Rails assets. Provide a string or a regular expression of the message patterns you would like to exclude.

“by logger = Yell.new do |l| l.silence /^Started GET “\/assets/ l.silence /^Served asset/ end

logger.debug ‘Started GET “/assets/logo.png” for 127.0.0.1 at 2013-06-20 10:18:38 +0200’ logger.debug ‘Served asset /logo.png - 304 Not Modified (0ms)’

“

Yell

Installation

Usage

=> “2012-02-29T09:30:00+01:00 [INFO] 65784 : Hello World”

^ ^ ^ ^

ISO8601 Timestamp Level Pid Message

Example: Notice messages go into `STDOUT` and error messages into `STDERR`

Example: Typical production Logger

Example: Typical production Logger for Heroku

But I’m used to Log4r and I don’t want to move on

create a logger named ‘mylog’ that logs to stdout

later in the code, you can get the logger back

create a logger named ‘mylog’ that logs to stdout

later in the code, you can get the logger back

Adding a logger to an existing class

Before you can use it, you will need to define a logger and

provide it with the `:name` of your class.

Now you can log

Given the above example, we inherit from Foo

The logger will fallback to the Foo superclass

Adding a logger to all classes at once (global logger)

Define a logger and pass `Object` as name. Internally, Yell adds this

logger to the repository where you can access it later on.

Enable logging for the class that (almost) every Ruby class inherits from

now you are good to go… from wherever you are

Suppress log messages with silencers

Further Readings

Additional Adapters

Development

Yell

Installation

Usage

=> “2012-02-29T09:30:00+01:00 [INFO] 65784 : Hello World”

^ ^ ^ ^

ISO8601 Timestamp Level Pid Message

Example: Notice messages go into STDOUT and error messages into STDERR

Example: Typical production Logger

Example: Typical production Logger for Heroku

But I’m used to Log4r and I don’t want to move on

create a logger named ‘mylog’ that logs to stdout

later in the code, you can get the logger back

create a logger named ‘mylog’ that logs to stdout

later in the code, you can get the logger back

Adding a logger to an existing class

Before you can use it, you will need to define a logger and

provide it with the :name of your class.

Now you can log

Given the above example, we inherit from Foo

The logger will fallback to the Foo superclass

Adding a logger to all classes at once (global logger)

Define a logger and pass Object as name. Internally, Yell adds this

logger to the repository where you can access it later on.

Enable logging for the class that (almost) every Ruby class inherits from

now you are good to go… from wherever you are

Suppress log messages with silencers

Further Readings

Additional Adapters

Development

Example: Notice messages go into `STDOUT` and error messages into `STDERR`

provide it with the `:name` of your class.

Define a logger and pass `Object` as name. Internally, Yell adds this