CentralLogger

Log to a central MongoDB from a Rails app

Usage

1. Install the plugin:

    # Rails 3
    rails plugin install git://github.com/customink/central_logger.git
    # Rails 2
    script/plugin install git://github.com/customink/central_logger.git
   

2. Add the following line to your ApplicationController:

    include CentralLogger::Filter
   

3. If using Rails < 3, configure environment.rb to use the CentralLogger (in config/environment.rb). Otherwise, the logger is automatically configured for all environments.

   require 'central_logger'
   CentralLogger::Initializer.initialize_deprecated_logger(config)
   

4. Add mongo settings to database.yml for each environment in which you want to use MongoDB for logging. The values below are defaults:

    development:
      adapter: mysql
      database: my_app_development
      user: root
      mongo:
        database: my_app               # required
        capsize: <%= 10.megabytes %>   # default: 250MB for production; 100MB otherwise
        host: localhost                # default: localhost
        port: 27017                    # default: 27017
   

With that in place, a new MongoDB document (record) will be created for each request and, by default will record the following information: Runtime, IP Address, Request Time, Controller, Action, Params and All messages sent to the logger. The structure of the Mongo document looks something like this:

    {
      'controller'    : controller_name,
      'action'        : action_name,
      'ip'            : ip_address,
      'runtime'       : runtime,
      'request_time'  : time_of_request,
      'params'        : { }
      'messages'      : {
                          'info'  : [ ],
                          'debug' : [ ],
                          'error' : [ ],
                          'warn'  : [ ],
                          'fatal' : [ ]
                        }
    }

Beyond that, if you want to add extra information to the base of the document (let’s say something like user_guid on every request that it’s available), you can just call the Rails.logger.add_metadata method on your logger like so (for example from a before_filter):

    # make sure we're using the CentralLogger in this environment
    if Rails.logger.respond_to?(:add_metadata)
      Rails.logger.add_metadata(:user_guid => @user_guid)
    end

1. And optionally, and PLEASE be sure to protect this behind a login, you can add a basic logging view by adding the following to your routes:

    map.add_central_logger_resources!
   

With that you can then visit /log to view log entries (latest first). You can add parameters like page=3 to page through to older entries, or count=30 to change the number of log entries per page.

Examples

And now, for a couple quick examples on getting ahold of this log data… First, here’s how to get a handle on the MongoDB from within a Rails console:

>> db = Rails.logger.mongo_connection
=> #<Mongo::DB:0x102f19ac0 @slave_ok=nil, @name="my_app" ... >

>> collection = db[Rails.logger.mongo_collection_name]
=> #<Mongo::Collection:0x1031b3ee8 @name="development_log" ... >

Once you’ve got the collection, you can find all requests for a specific user (with guid):

>> cursor = collection.find(:user_guid => '12355')
=> #<Mongo::Cursor:0x1031a3e30 ... >
>> cursor.count
=> 5

Find all requests that took more that one second to complete:

>> collection.find({:runtime => {'$gt' => 1000}}).count
=> 3

Find all order#show requests with a particular order id (id=order_id):

>> collection.find({"controller" => "order", "action"=> "show", "params.id" => order_id})

Find all requests with an exception that contains "RoutingError" in the message or stack trace:

>> collection.find({"messages.error" => /RoutingError/})

Copyright (c) 2009 Phil Burrows, released under the MIT license