Rack::Timeout

Abort requests that are taking too long; an exception is raised.

A timeout of 15s is the default. It's recommended to set the timeout as low as realistically viable for your application. You can modify this by setting the RACK_TIMEOUT_SERVICE_TIMEOUT environment variable.

There's a handful of other settings, read on for details.

Rack::Timeout is not a solution to the problem of long-running requests, it's a debug and remediation tool. App developers should track rack-timeout's data and address recurring instances of particular timeouts, for example by refactoring code so it runs faster or offsetting lengthy work to happen asynchronously.

Upgrading

For fixing issues when upgrading, please see UPGRADING.

Basic Usage

The following covers currently supported versions of Rails, Rack, Ruby, and Bundler. See the Compatibility section at the end for legacy versions.

Rails apps

# Gemfile
gem "rack-timeout"

This will load rack-timeout and set it up as a Rails middleware using the default timeout of 15s. The middleware is not inserted for the test environment. You can modify the timeout by setting a RACK_TIMEOUT_SERVICE_TIMEOUT environment variable.

Rails apps, manually

You'll need to do this if you removed Rack::Runtime from the middleware stack, or if you want to determine yourself where in the stack Rack::Timeout gets inserted.

# Gemfile
gem "rack-timeout", require: "rack/timeout/base"

# config/initializers/rack_timeout.rb

# insert middleware wherever you want in the stack, optionally pass
# initialization arguments, or use environment variables
Rails.application.config.middleware.insert_before Rack::Runtime, Rack::Timeout, service_timeout: 15

Sinatra and other Rack apps

# config.ru
require "rack-timeout"

# Call as early as possible so rack-timeout runs before all other middleware.
# Setting service_timeout or `RACK_TIMEOUT_SERVICE_TIMEOUT` environment
# variable is recommended. If omitted, defaults to 15 seconds.
use Rack::Timeout, service_timeout: 15

Configuring

Rack::Timeout takes the following settings, shown here with their default values and associated environment variables.

service_timeout:   15     # RACK_TIMEOUT_SERVICE_TIMEOUT
wait_timeout:      30     # RACK_TIMEOUT_WAIT_TIMEOUT
wait_overtime:     60     # RACK_TIMEOUT_WAIT_OVERTIME
service_past_wait: false  # RACK_TIMEOUT_SERVICE_PAST_WAIT
term_on_timeout:   false  # RACK_TIMEOUT_TERM_ON_TIMEOUT

These settings can be overriden during middleware initialization or environment variables RACK_TIMEOUT_* mentioned above. Middleware parameters take precedence:

use Rack::Timeout, service_timeout: 15, wait_timeout: 30

For more on these settings, please see doc/settings.

Further Documentation

Please see the doc folder for further documentation on:

• Risks and shortcomings of using Rack::Timeout
• Understanding the request lifecycle
• Exceptions raised by Rack::Timeout
• Rollbar fingerprinting
• Observers
• Settings
• Logging

Additionally there is a demo app that shows the impact of changing settings and how the library behaves when a timeout is hit.

Compatibility

This version of Rack::Timeout is compatible with Ruby 2.1 and up, and, for Rails apps, Rails 3.x and up.

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Copyright © 2010-2020 Caio Chassot, released under the MIT license http://github.com/sharpstone/rack-timeout