Custom Logger Example on Rails

activity_logger.rb

# lib/activity_logger.rb
class ActivityLogger < Logger
  def format_message(severity, timestamp, progname, msg)
    base_log = {
      timestamp: timestamp,
      severity: severity
    }
    base_log.merge(msg).to_json + "\n"
  end
end

logfile = File.open("#{Rails.root}/log/activity.log", 'a')
logfile.sync = true

ACTIVITY_LOGGER = ActivityLogger.new(logfile)

application_controller.rb

# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  before_action :log_activity
  
  private
  
  def log_activity
    ACTIVITY_LOGGER.info(
      session_id:      session.id,
      user_id:         session[:id],
      status:          response.status,
      remote_ip:       request.remote_ip,
      method:          request.method,
      path:            request.path,
      query_string:    request.query_string,
      url:             request.url,
      user_agent:      request.user_agent,
      body:            request.body
    )
  end
end

autoloads.rb

# config/initializers/autoloads.rb
require './lib/activity_logger'