Datadog::JSONLogger

Datadog::JSONLogger is a Ruby gem designed to seamlessly integrate Ruby applications with Datadog's logging and tracing services. This gem allows your Ruby application to format its output as JSON, including necessary correlation IDs and other details for optimal Datadog functionality.

Prerequisites

Before you begin, ensure you have ddtrace configured in your Ruby application, as Datadog::JSONLogger relies on ddtrace for tracing data.

Installation

Add this line to your application's Gemfile:

gem 'datadog-json_logger'

And then execute:

bundle install

Or install it yourself as:

gem install datadog-json_logger

Usage

JSONLogger

Datadog::JSONLogger can be easily integrated into your Ruby application. Here's a quick example of how to use it in a Sinatra application:

# Example in Sinatra (app.rb)
require 'datadog/json_logger'

Datadog::JSONLogger.configure do |config|
  config.current_user = ->(env) { { email: env['warned'].user.email } } # Log user on each request
  config.controller_key = "sinatra.controller_name"
  config.resource_key   = "sinatra.resource_name"
  config.action_key     = "sinatra.action_name"
end

def logger
  @logger ||= Datadog::JSONLogger.new
end

set :logger, logger

Sinatra::Application.logger.info("hello")
# => {"dd":{"trace_id":"0","span_id":"0","env":null,"service":"console","version":null},"timestamp":"2023-11-22 22:28:00 +0100","severity":"INFO ","progname":"","message":"hello"}

Add Custom Keys

Create a custom formatter that inherits from Datadog::Loggers::JSONFormatter to add custom keys as shown below:

class CustomFormatter < Datadog::Loggers::JSONFormatter
  def self.call(severity, datetime, progname, msg)
    super do |log_hash|
      log_hash[:my_custom_key] = "my_value"
      log_hash[:my_custom_hash] = { key: "value" }
    end
  end
end

def logger
  return @logger if @logger

  @logger = Datadog::JSONLogger.new
  @logger.progname = "my_app"
  @logger.formatter = CustomFormatter
  @logger
end

Sinatra::Application.logger.info("hello")
# {"dd":{"trace_id":"0","span_id":"0","env":null,"service":"console","version":null},"timestamp":"2023-11-22 22:46:01 +0100","severity":"INFO ","progname":"my_app","message":"hello","my_custom_key":"my_value","my_custom_hash":{"key":"value"}}

SinatraMiddleware

Datadog::SinatraMiddleware formats Rack requests as JSON and disables the default textual stdout of Rack::CommonLogger:

# Example in Sinatra (app.rb)
require 'datadog/sinatra_middleware'

use Datadog::SinatraMiddleware, logger

Features

Feature	Link	Compatibility
JSON correlated logging	Ruby Collection	✅
Tracing	Ruby Tracing application	✅
Error Tracking	Datadog error tracking	✅

Development

After checking out the repo, run bundle install to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/buyco/datadog-json-logger. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

1. Fork the repository (https://github.com/buyco/datadog-json-logger/fork)
2. Create your feature branch (git checkout -b feature/my_feature)
3. Commit your changes (git commit -am 'Add a new feature')
4. Push the branch (git push origin feature/my_feature)
5. Open a Pull Request

License

This gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Datadog::JSONLogger project's codebases, issue trackers, chat rooms, and mailing lists is expected to follow the code of conduct.