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Use as Rails logger

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Toshimitsu Takahashi edited this page Nov 3, 2025 · 5 revisions

Define a custom logger

Add following code to lib/your_app/logger.rb A custom logger includes LoggerSilence because Rails logger must support silence feature.

module YourApp class Logger < Ougai::Logger include ActiveSupport::LoggerThreadSafeLevel include ActiveSupport::LoggerSilence def initialize(*args) super after_initialize if respond_to?(:after_initialize) && ActiveSupport::VERSION::MAJOR < 6 end def create_formatter if Rails.env.development? || Rails.env.test? Ougai::Formatters::Readable.new else Ougai::Formatters::Bunyan.new end end end end

for Development

Add following code to config/environments/development.rb

Rails.application.configure do ... config.logger = YourApp::Logger.new(STDOUT) end

for Production

Add following code to the end block of config/environments/production.rb

Rails.application.configure do ... if ENV["RAILS_LOG_TO_STDOUT"].present? config.logger = YourApp::Logger.new(STDOUT) else config.logger = YourApp::Logger.new(config.paths['log'].first) end end

With Lograge

You must modify lograge formatter like Raw. The following code set request data to request field of JSON.

Rails.application.configure do config.lograge.enabled = true config.lograge.formatter = Class.new do |fmt| def fmt.call(data) { msg: 'Request', request: data } end end end

Output example on development

If you modify application_controller.rb as

class ApplicationController < ActionController::Base protect_from_forgery with: :exception def hello logger.debug 'Call action', somefield: 'somevalue' render plain: 'Hello!' end end

logger outputs following:

[2016-11-03T15:11:24.847+09:00] DEBUG: Call action { :somefield => "somevalue" } [2016-11-03T15:11:24.872+09:00] INFO: Request { :request => { :method => "GET", :path => "/", :format => :html, :controller => "ApplicationController", :action => "hello", :status => 200, :duration => 30.14, :view => 3.35, :db => 0.0 } }

With ActiveSupport::TaggedLogging

Apply the monkey patch as below and embed the tags as a field on output

Rails.application.configure do ... module ActiveSupport::TaggedLogging::Formatter def call(severity, time, progname, data) data = { msg: data.to_s } unless data.is_a?(Hash) tags = current_tags data[:tags] = tags if tags.present? _call(severity, time, progname, data) end end config.logger = ActiveSupport::TaggedLogging.new(YourApp::Logger.new(STDOUT)) end

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