Logging and Instrumentation

Logging

To write requests and responses to a logger, use the Logging feature:

logger = Logger.new(STDOUT)
http = HTTP.use(logging: {logger: logger})

http.get("https://httpbin.org/get")
# I, [2018-08-16T16:33:58.261195 #1538]  INFO -- : > GET https://httpbin.org/get
# I, [2018-08-16T16:33:58.487195 #1538]  INFO -- : < 200 OK

Logging at the DEBUG level will log the full request & response headers and bodies.

To enable it for all requests by default use default_options

HTTP.default_options = HTTP::Options.new(features: {
                                           logging: {
                                             logger: Logger.new(STDOUT)
                                           }
                                         })

Instrumentation

For more advanced logging, or instrumentation in general, use the Instrumentation feature. It expects an ActiveSupport::Notifications-compatible instrumenter.

ActiveSupport::Notifications.subscribe('start_request.http') do |name, start, finish, id, payload|
  pp :name => name, :start => start.to_f, :finish => finish.to_f, :id => id, :payload => payload
end

http = HTTP.use(instrumentation: { instrumenter: ActiveSupport::Notifications.instrumenter })
http.get("https://httpbin.org/get")
# => {name: .., start: .., finish: .., id: .., payload: ..}

You can customize the "namespace" used by the instrumenter:

HTTP.use(instrumentation: { instrumenter: ActiveSupport::Notifications.instrumenter, namespace: "my_http" })
# Will emits a "request.my_http" event on requests.

Custom implementations

http.rb also supports defining custom features.

In order to register your own custom feature implementation, implement HTTP::Feature, and then register it with the HTTP library:

HTTP::Options.register_feature(:my_feature, MyFeature)

You can then use it on a client via:

http = HTTP.use(:my_feature)