Cute Logger

This gem provides accesible methods for doing the application logging in a simple manner.

Description

Cute Logger provides globally accesible methods to do the logging. It also provides a log parser command for easy view during development. The gem includes mechanisms for log rotation, improved exception logging and nice formatted log viewing among many other features and best practices.

Please refer to the document Better Logging for a better understanding of the functionality of Cute Logger.

Installation

Add this line to your application's Gemfile:

gem 'cute_logger'

And then execute:

$ bundle update

Or install it yourself as:

$ gem install cute_logger

Usage

To use this gem, require it into your application and optionally call the setup function to specify how the log information should be stored, for how long and the minimum accepted severity.

require 'cute_logger'

CuteLogger.setup(
    filename: 'application.log',
    severity: 'INFO',
    shift_age: 7, # 7 days
    shift_size: 1024 * 1024 * 1024 # On gigabyte
)

The previous values are actually the default ones if the setup method is not explicitly called.

To log something you could use the following formats:

log_info('Some event')
log_info('Some event', status: 'Working', value: '123')
log_debug(my_hash)
log_debug { 'Delayed evaluation' }
log_info('MyAppName') { 'Something to log' }
log_error('Error X', my_exception)

Hashes and arrays are logged as JSON format:

my_array = {a: 'letter A', b: [1, 2, 3]}
log_info('Useful data', data: my_array)

Results in an entry like the following:

2017-04-21 22:12:56 -0500,INFO,a801,3ff44803f9f4,Object,["Useful data",{"data":{"a":"letter A","b":["1","2","3"]}}]

To view the log in a cute format (awesome_print):

$ cat application.log | cute_log

2017-04-21 22:12:56 -0500 INFO 43009-3ff44803f9f4 (Object)
[
    [0] "Useful data",
    [1] {
        "data" => {
            "a" => "letter A",
            "b" => [
                [0] "1",
                [1] "2",
                [2] "3"
            ]
        }
    }
]

Exceptions have their own formatting:

begin
  nil.hello
rescue => error
  log_error('Error during X event', error: error)
end

$ cat application.log | cute_log

2017-04-21 22:18:28 -0500 ERROR 44691-3fe53703fa14 (Object)
[
    [0] "Error during X event",
    [1] {
        "error" => {
                "class" => "NoMethodError",
              "message" => "undefined method `hello' for nil:NilClass",
            "backtrace" => [
                [ 0] "(irb):3:in `irb_binding'",
                [ 1] "/Users/johndoe/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87:in `eval'",
                [ 2] "/Users/johndoe/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87:in `evaluate'",
                [ 3] "/Users/johndoe/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/context.rb:380:in `evaluate'",
                [ 4] "/Users/johndoe/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb.rb:489:in `block (2 levels) in eval_input'",
               ... log intentionally cutted down for better legibility  ...
            ]
        }
    }
]

The cute_log script utility helps to visualize the contents of the log. For example:

# View the all the logs
$ cat application.log | cute_log

# View the logs in real time with awesome print
$ tail -F application.log | cute_log

# View the logs in real time with JSON pretty_generate
$ tail -F application.log | cute_log --json

# View all errors with awesome print (The switch --awesome is the default anyway)
$ grep "ERROR" application.log | cute_log --awesome

# View all errors of ID 223
$ grep "ERROR" application.log | grep "ID000233" | cute_log

# View all warns from Jaunuary 2017
$ grep "WARN" application.log | grep "2017-01" | cute_log

Using environment variables

It is possible to configure the logging settings via environment variables. For example:

export CUTE_LOGGER_FILENAME=archive.log
export CUTE_LOGGER_SHIFT_AGE=7
export CUTE_LOGGER_SHIFT_SIZE=1000000
export CUTE_LOGGER_SEVERITY=DEBUG

This is the recommended way to configuring the logger settings.

Development