Sensible Logging

A logging extension with sensible defaults for Sinatra apps.

Features

• Add a request UUID (or use an existing one if present in the X-Request-Id HTTP header) for use in logs, your app or other middlewares
• Trim the request logs to the bare minimal (inspired by lograge):
  • method
  • path
  • requesting IP address
  • status
  • duration
  • params if a GET request

Example log line:

  method=GET path=/contact client=192.168.1.254 status=200 duration=0.124 params={"category"=>"question"}

• Tagged logging, with some sensible defaults:
  • severity
  • subdomain
  • environment
  • request UUID

Example log line:

  [INFO] [www.gb] [staging] [6004bb70-7b6d-43b6-a2cf-72d0336663ba] @todo tidy sql query

Usage

1. Add sensible_logging to your Gemfile and install with bundle install:

  gem 'sensible_logging'

1. In your app.rb register the module and then define your logging configuration:

  require 'sensible_logging'

  class App < Sinatra::Base
    register Sinatra::SensibleLogging

    # Initialise Sensible Logging to add our middlewares.
    sensible_logging(
      logger: Logger.new($stdout)
      )

    # Configure the log level for different environments
    configure :production do
      set :log_level, Logger::INFO
    end

    # Requests will be logged in a minimal format
    get '/' do
      'Hello!'
    end

    get '/about' do
      # The standard Sinatra logger helper will use the Sensible Logging gem
      logger.info('About page')
    end

    get '/contact' do
      # In addition to the default tags, you can add additional ones by using the `tagged` block on the `logger` helper
      # [INFO] [localhost] [development] [a9d0183d-a3c3-4081-b502-38dcf4c3c4d7] [todo] Contact page
      logger.tagged('todo') do |logger|
        logger.info('Contact page')
      end
    end

  # rest of code omitted

Available options

There are a number of options that you can pass into sensible_logging:

• logger: The logging object. Default: Logger.new($stdout)
• use_default_log_tags: Includes the subdomain, RACK_ENV and unique request ID in the log tags. Default: true
• tld_length: For example, if your domain was www.google.com this would result in www being tagged as your subdomain. If your domain is www.google.co.uk, set this value to 2 to correctly identify the subdomain as www rather than www.google. Default: 1.
• log_tags: An array of additional log tags to include. This can be strings, or you can include a lambda that will be evaluated. The lambda is passed a Rack Request object, and it must return an array of string values. Default: []
• exclude_params: An array of parameter names to be excluded from GET requests. By default, GET parameters are outputted in logs. If for example with the request http://google.com/?one=dog&two=cat you didn't want the one logged, you would set exclude_params to be ['one'] Default: []
• include_log_severity: Includes the log severity in the tagged output, such as INFO, DEBUG etc Default: true

Sensible Logger will also respect the following Sinatra settings:

• log_level: The level at which your logger object should respect logs. See above example. Default: Logger::DEBUG

Examples

There is an example Sinatra app included in this repo. Here's how to use it:

bundle install
cd examples
rackup

With the app running, run some curl commands against it:

curl 'localhost:9292/hello?one=two&two=three'

You should notice in the logs:

• Standard Sinatra logger helper works out of the box within apps with tags.
• Excluded parameters are not included, in this example two based on config.ru
• The request log is minimal compared to out of the box Sinatra.
• env['request_id'] is now available to group log lines from the same request together, or to use in additional services such as Sentry.

FAQ

Why is the timestamp absent?

To quote lograge (which was the inspiration for this library):

The syntax is heavily inspired by the log output of the Heroku router. It doesn't include any timestamp by default, instead, it assumes you use a proper log formatter instead.

Releasing

1. Update the version number lib/sensible_logging/version.rb
2. Create a git commit and tag with the new version number: git tag -a v0.4.2 -m "v0.4.2"
3. Create a new PR with this change and once approved, merge to main
4. Once approved and merged in, locally, run: bundle exec rake release which will build and push the new gem to Rubygems

Authors

By David Winter with contributions from Mark Sta Ana & Anthony King

License

MIT