Heavylog

Heavylog enables you to log all Rails requests to file as JSON or any other format you want.

Aside from metadata about requests full output is also included like SQL/Rails logging and puts statements.
Example request using the JSON formatter:

{"request_id":"e2cdef0a-9851-4aab-b58f-60e607b4d1a9","request_start":"2021-04-25T15:37:20+00:00","ip":"52.52.52.52","messages":"Started GET \"/admin/info/sidekiq\" for 52.52.52.52 at 2021-04-25 15:37:20 +0000\nProcessing by Admin::InfoController#sidekiq_stats as */*\nRequested via apphost.com as */*\n  Snippet Load (1.8ms)  SELECT \"snippets\".* FROM \"snippets\" WHERE (locale = 'sv-SE' AND tag = 'information_notice_contact') ORDER BY \"snippets\".\"id\" ASC LIMIT $1  [[\"LIMIT\", 1]]\n  Snippet Load (1.5ms)  SELECT \"snippets\".* FROM \"snippets\" WHERE (locale = 'sv-SE' AND tag = 'contact_us_frame') ORDER BY \"snippets\".\"id\" ASC LIMIT $1  [[\"LIMIT\", 1]]\n  Rendering text template\n  Rendered text template (Duration: 0.1ms | Allocations: 16)\nCompleted 200 OK in 41ms (Views: 0.6ms | ActiveRecord: 3.3ms | Allocations: 10734)\n","method":"GET","path":"/admin/info/sidekiq","format":"*/*","controller":"Admin::InfoController","action":"sidekiq_stats","status":200,"duration":40.74,"view_runtime":0.56,"db_runtime":3.28,"user_id":null,"admin_id":null,"request_host":"apphost.com","ua":"curl/7.58.0","operation":null}

Example use case is collecting the JSON files and shipping them to an Elastic/Kibana cluster for centralized logging.

Installation

Add this line to your application's Gemfile:

gem "heavylog"

And then execute:

$ bundle

Usage

Enable and configure in a Rails initializer config/initializers/logger.rb:

Rails.application.configure do
  config.heavylog.enabled = true
  config.heavylog.path = Rails.root.join("log/heavylog.log")
  # Default formatter is Heavylog::Formatters::Raw which simply outputs the ruby hash as a string
  config.heavylog.formatter = Heavylog::Formatters::Json.new
  config.heavylog.log_sidekiq = true # Default is `false`, set to `true` to automatically log sidekiq job runs too.
end

Configuration

Option	Type	Description
enabled	boolean	Set to true to enable logging. Default: false.
path	string	Path to output file. Default: log/heavylog.log.
message_limit	integer	Request output will be truncated if longer than this limit. Default: 52428800 (50MB).
log_sidekiq	boolean	Set to true to automatically log sidekiq jobs too. Default: false.
error_handler	lambda/proc	Code to execute when formatter throws exception. Default: ->(e) { p "HeavyLog: Error writing to log: #{e.class}: #{e.message}\n #{e.backtrace.join("\n ")}" }
custom_payload	block	Block executed for every request that should return hash with extra fields you want to log. Default: nil.

Custom payload

custom_payload accepts a block with a single argument, controller you can use to access any methods you normally would in a controller action.
It should return a hash with the extra fields you want to log.

Rails.application.configure do
  config.heavylog.custom_payload do |controller|
    user_id = controller.respond_to?(:current_user) ? controller.current_user&.id : nil

    {
      user_id:      user_id,
      request_host: controller.request.host,
      ua:           controller.request.user_agent,
      operation:    controller.request.params[:operationName],
    }
  end
end

Sidekiq logging

Set log_sidekiq to true if you want to automatically log Sidekiq job runs to the same file. Example with JSON formatter:

{"request_id":"fb2c3798e2634011d670f753","request_start":"2021-04-25T16:00:53+00:00","ip":"127.0.0.1","messages":"  Order Load (1.8ms)  SELECT \"orders\".* FROM \"orders\" WHERE \"orders\".\"id\" = $1 LIMIT $2  [[\"id\", 109987473], [\"LIMIT\", 1]]\n  Customer Load (1.7ms)  SELECT \"customers\".* FROM \"customers\" WHERE \"customers\".\"id\" = $1 LIMIT $2  [[\"id\", 1027337], [\"LIMIT\", 1]]\n","controller":"SidekiqLogger","action":"MailPrepaidCheckupsJob","args":"[109987473]"}

Sidekiq job runs go into the same file as regular request logs but have controller set to SidekiqLogger and action to the name of the Job.

JSON formatter

Every request results in a hash containing all info about the request. The default Heavylog::Formatters::Raw formatter simply outputs the hash as a string to the output file.
Use the Heavylog::Formatters::Json formatter to convert the hash to JSON. The resulting file will contain one JSON object per line for every request.

Custom formatter

The formatter interface is simply a class with a call method that accepts a single argument which is the hash containing info about the request.
The method should return the final result you want to write to file. Heavylog writes one line per request.

JSON formatter for example:

class Json
  def call(data)
    ::JSON.dump(data)
  end
end

License

MIT