This gem is heavily inspired from lograge, but it's focused on one thing and one thing only. That's making your logs awesome like this:

How it's done ?

By, using these awesome tools:

• Logstash - Store and index your logs
• Kibana - for awesome visualization. This is optional though, and you can use any other visualizer

Update: Logstash now includes Kibana build in, so no need to separately install. Logstasher has been tested with logstash version 1.4.2 with file input and json codec.

See quickstart for quickly setting up logstash

This gem purely focuses on how to generate logstash compatible logs i.e. logstash json event format, without any overhead. Infact, logstasher logs to a separate log file named logstash_<environment>.log. The reason for this separation:

• To have a pure json log file
• Prevent any logger messages(e.g. info) getting into our pure json logs

Before logstasher :

Started GET "/login" for 10.109.10.135 at 2013-04-30 08:59:01 -0400
Processing by SessionsController#new as HTML
  Rendered sessions/new.html.haml within layouts/application (4.3ms)
  Rendered shared/_javascript.html.haml (0.6ms)
  Rendered shared/_flashes.html.haml (0.2ms)
  Rendered shared/_header.html.haml (52.9ms)
  Rendered shared/_title.html.haml (0.2ms)
  Rendered shared/_footer.html.haml (0.2ms)
Completed 200 OK in 532ms (Views: 62.4ms | ActiveRecord: 0.0ms | ND API: 0.0ms)

After logstasher:

{"@source":"unknown","@tags":["request"],"@fields":{"method":"GET","path":"/","format":"html","controller":"file_servers"
,"action":"index","status":200,"duration":28.34,"view":25.96,"db":0.88,"ip":"127.0.0.1","route":"file_servers#index",
"parameters":"","ndapi_time":null,"uuid":"e81ecd178ed3b591099f4d489760dfb6","user":"[email protected]",
"site":"internal"},"@timestamp":"2013-04-30T13:00:46.354500+00:00"}

By default, the older format rails request logs are disabled, though you can enable them.

In your Gemfile:

gem 'logstasher'

# Enable the logstasher logs for the current environment
config.logstasher.enabled = true

# This line is optional if you do not want to suppress app logs in your <environment>.log
config.logstasher.suppress_app_log = false

# This line is optional, it allows you to set a custom value for the @source field of the log event
config.logstasher.source = 'your.arbitrary.source'

# This line is optional if you do not want to log the backtrace of exceptions
config.logstasher.backtrace = false

# This line is optional, defaults to log/logstasher_<environment>.log
config.logstasher.logger_path = 'log/logstasher.log'

Logstasher can be configured to log the contents of the params hash. When enabled, the contents of the params hash (minus the ActionController internal params) will be added to the log as a deep hash. This can cause conflicts within the Elasticsearch mappings though, so should be enabled with care. Conflicts will occur if different actions (or even different applications logging to the same Elasticsearch cluster) use the same params key, but with a different data type (e.g. a string vs. a hash). This can lead to lost log entries. Enabling this can also significantly increase the size of the Elasticsearch indexes.

To enable this, add the following to your <environment>.rb

# Enable logging of controller params
config.logstasher.log_controller_parameters = true

Since some fields are very specific to your application for e.g. user_name, so it is left upto you, to add them. Here's how to add those fields to the logs:

# Create a file - config/initializers/logstasher.rb

if LogStasher.enabled?
  LogStasher.add_custom_fields do |fields|
    # This block is run in application_controller context,
    # so you have access to all controller methods
    fields[:user] = current_user && current_user.mail
    fields[:site] = request.path =~ /^\/api/ ? 'api' : 'user'

    # If you are using custom instrumentation, just add it to logstasher custom fields
    LogStasher.custom_fields << :myapi_runtime
  end
end

Logstasher can easily log messages from ActionMailer, such as incoming/outgoing e-mails and e-mail content generation (Rails >= 4.1). This functionality is automatically enabled. Since the relationship between a concrete HTTP request and a mailer invocation is lost once in an ActionMailer instance method, global (per-request) state is kept to correlate HTTP requests and events from other parts of rails, such as ActionMailer. Every time a request is invoked, a request_id key is added which is present on every ActionMailer event.

Note: Since mailers are executed within the lifetime of a request, they will show up in logs prior to the actual request.

It is possible to listen to any ActiveSupport::Notifications events and store arbitrary data to be included in the final JSON log entry:

# In config/initializers/logstasher.rb

# Watch calls the block with the same arguments than any ActiveSupport::Notification, plus a store
LogStasher.watch('some.activesupport.notification') do |name, start, finish, id, payload, store|
  # Do something
  store[:count] = 42
end

Would change the log entry to:

{"@source":"unknown","@tags":["request"],"@fields":{"method":"GET","path":"/","format":"html","controller":"file_servers","action":"index","status":200,"duration":28.34,"view":25.96,"db":0.88,"ip":"127.0.0.1","route":"file_servers#index", "parameters":"","ndapi_time":null,"uuid":"e81ecd178ed3b591099f4d489760dfb6","user":"[email protected]", "site":"internal","some.activesupport.notification":{"count":42}},"@timestamp":"2013-04-30T13:00:46.354500+00:00"}

The store exposed to the blocked passed to watch is thread-safe, and reset after each request. By default, the store is only shared between occurences of the same event. You can easily share the same store between different types of notifications, by assigning them to the same event group:

# In config/initializers/logstasher.rb

LogStasher.watch('foo.notification', event_group: 'notification') do |*args, store|
  # Shared store with 'bar.notification'
end

LogStasher.watch('bar.notification', event_group: 'notification') do |*args, store|
  # Shared store with 'foo.notification'
end

• Download logstash from logstash.net
• Use this sample config file: quickstart.conf
• Start logstash with the following command:

java -jar logstash-1.3.3-flatjar.jar agent -f quickstart.conf -- web

• Visit http://localhost:9292/ to see the Kibana interface and your parsed logs
• For advanced options see the latest logstash documentation at logstash.net or visit my blog at shadabahmed.com (slightly outdated but will sure give you ideas for distributed setup etc.)

All versions require Rails 3.0.x and higher and Ruby 1.9.2+. Tested on Rails 4 and Ruby 2.0

• Run tests - rake
• Generate test coverage report - rake coverage. Coverage report path - coverage/index.html

Copyright (c) 2013 Shadab Ahmed, released under the MIT license