Superlogger - Machine-readable logging for Rails

Rails' default request logging is easy to read for humans but difficult for log aggregators such as Kibana, Graylog and Splunk. Superlogger transforms the logs into JSON for easy parsing and adds useful details like Timestamp, Session ID and Request ID for tracing purposes.

Default rails logging:

Started GET "/home/index" for ::1 at 2016-04-29 17:31:12 +0800
  ActiveRecord::SchemaMigration Load (0.1ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Processing by HomeController#index as HTML
  Something Load (0.1ms)  SELECT  "somethings".* FROM "somethings" WHERE "somethings"."paper" = ? AND "somethings"."stone" = ?  ORDER BY "somethings"."id" ASC LIMIT 1  [["paper", "123"], ["stone", "456"]]
  Rendered home/_partial.html.erb (0.2ms)
  Rendered home/index.html.erb within layouts/application (3.4ms)
Completed 200 OK in 135ms (Views: 130.7ms | ActiveRecord: 0.3ms)

Started GET "/assets/application.self-e80e8f2318043e8af94dddc2adad5a4f09739a8ebb323b3ab31cd71d45fd9113.css?body=1" for ::1 at 2016-04-29 17:31:12 +0800

Started GET "/assets/application.self-8f06a73c35179188914ab50e057157639fce1401c1cdca640ac9cec33746fc5b.js?body=1" for ::1 at 2016-04-29 17:31:12 +0800

With Superlogger:

{"level":"debug","ts":1590972589.522784,"caller":"superlogger/active_record_log_subscriber:21","sql":"SELECT \"schema_migrations\".\"version\" FROM \"schema_migrations\" ORDER BY \"schema_migrations\".\"version\" ASC","params":[],"duration":0.13}
{"level":"info","ts":1590972589.526133,"caller":"superlogger/superlogger_middleware:21","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","method":"GET","path":"/home/index"}
{"level":"debug","ts":1590972589.546272,"caller":"superlogger/action_controller_log_subscriber:8","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","controller":"HomeController","action":"index","params":{}}
{"level":"debug","ts":1590972589.55092,"caller":"superlogger/active_record_log_subscriber:21","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","sql":"SELECT  \"somethings\".* FROM \"somethings\" WHERE \"somethings\".\"paper\" = ? AND \"somethings\".\"stone\" = ? ORDER BY \"somethings\".\"id\" ASC LIMIT ?","params":["123","456","1"],"duration":0.22}
{"level":"debug","ts":1590972589.574199,"caller":"superlogger/action_view_log_subscriber:6","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","view":"_partial.html.erb","duration":0.33}
{"level":"debug","ts":1590972589.574795,"caller":"superlogger/action_view_log_subscriber:6","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","view":"index.html.erb","duration":2.95}
{"level":"info","ts":1590972589.61165,"caller":"superlogger/action_controller_log_subscriber:20","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","view_duration":54.59,"db_duration":0.85}
{"level":"info","ts":1590972589.611928,"caller":"superlogger/superlogger_middleware:30","session_id":"90e90c75c72c","request_id":"34432478c89b4d8591e02e0169b40a56","method":"GET","path":"/home/index","response_time":85.65,"status":200}

Installation

Add superlogger to your application's Gemfile

gem "superlogger"

Execute:

$ bundle

And add the following in config/environment/production.rb

config.logger = Superlogger::Logger.new(STDOUT)

By default, Superlogger is only enabled in production environment because JSON is easy for machines to parse but difficult for humans to read. To forcefully enable Superlogger in non-production environment, set in config/application.rb:

Superlogger.enabled = true

Usage

Log as per normal using Rails.logger.

Rails.logger.info foo:'true', bar: 'false'
Rails.logger.info "Meatball"

Log Format

ts = Unix Epoch timestamp
session_id = Truncated to 12 characters
request_id = 32 characters
msg = If values given is not a hash, it is treated as {"msg":<value>"}
All duration related fields are in milliseconds

superlogger

Runtime

Superlogger - Machine-readable logging for Rails

Installation

Usage

Log Format