API logger with Grape under Rails

api_logger.rb

class ApiLogger < Grape::Middleware::Base
  
  def before
    Rails.logger.info "[api] Requested: #{request_log_data.to_json}\n" +
     "[api] #{response_log_data[:description]} #{response_log_data[:source_file]}:#{response_log_data[:source_line]}"
  end
  
private

  def request_log_data
    request_data = {
      method: env['REQUEST_METHOD'],
      path:   env['PATH_INFO'],
      query:  env['QUERY_STRING']
    }
    request_data[:user_id] = current_user.id if current_user
    request_data
  end

  def response_log_data
    {
      description: env['api.endpoint'].options[:route_options][:description],
      source_file: env['api.endpoint'].block.source_location[0][(Rails.root.to_s.length+1)..-1],
      source_line: env['api.endpoint'].block.source_location[1]
    }
  end

end

@dblock how would you suggest handling post params? I have something like this, but I don't think its very clean. Plus the resulting hash that gets logged isn't as clean as post params being logged in rails:

 def request_log_data
    # Escape the ampersand in the POST data.
    rack_input = env["rack.input"].gets

    if rack_input.present?
      rack_input = rack_input.gsub("&","%26")
      params_data = Rack::Utils.parse_query(rack_input, "&")
    else
      params_data = nil
    end

    request_data = {
      method: env['REQUEST_METHOD'],
      path:   env['PATH_INFO'],
      query:  env['QUERY_STRING'],
      params: params_data
    }
    # request_data[:user_id] = current_user.id if current_user
    request_data
  end

Any suggestions?

What does Rails log for POST params? Maybe we can replicate something similar?

Are the helper methods such as current_user available in the middleware? I have been trying to call those methods but I always get method not found exception.

@hamin - howdy padner! Do you have any updates to the logger? I am just stumbling onto this now. I've been manually logging params where needed, but I want to implement a global solution now.

Update: I went ahead and kicked its ass. Also @dblock

ruby-grape/grape#894

Just recently created gem that accomplish something very similar. Just few lines of code in your app and you will get one log line per request with: status code, path, request time, db time and parameters.

Check it out: https://rubygems.org/gems/grape_logging

@aserafin -- can you specify where to put those two lines of code -- Ruby beginner here.

@hamin Yes, dirty... I found a nasty bug in this code:

        # Rack::Utils.parse_query('♥')
        # /.../vendor/bundle/ruby/2.2.0/gems/rack-1.6.4/lib/rack/utils.rb:92: warning: regexp match /.../n against to UTF-8 string
        # => {"♥"=>nil}
        # [2] pry(#<Backbone::ApiLogger>)> Rack::Utils.parse_query('%')
        # ArgumentError: invalid %-encoding (%)
        # from /home/xxx/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/uri/common.rb:382:in `decode_www_form_component'

so the percent sign has to be escaped too, in case somebody wants to use it

rack_input = rack_input.gsub("&", "%26").gsub("%", "%25")