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rack-idempotent

branch: master
README.md

Rack::Idempotent

This rack middleware intends to handle retry logic for rack-client.

Rack::Idempotent rescues and retries low-level errors and 'safe to retry' http response codes.

Default retry limit is currently set to 5.

Handled low-level Net::HTTP exceptions include:

  • Errno::ETIMEDOUT
  • Errno::ECONNREFUSED
  • Errno::EHOSTUNREACH

Response status codes that are retried:

  • 408: Request Timeout
  • 502: Bad Gateway
  • 503: Service Unavailable
  • 504: Gateway Timeout

If the retry limit is exceeded, Rack::Idemptotent will raise Rack::Idempotent::RetryLimitExceeded.

The exceptions raised are stored as an array available via Rack::Idempotent::RetryLimitExceeded#idempotent_exceptions

Installation

Add this line to your application's Gemfile:

gem 'rack-idempotent'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rack-idempotent

Usage

Add Rack::Idempotent as a Rack::Client middleware as close to the handler as possible:

client = Rack::Client.new do
  use EY::ApiHMAC::ApiAuth::Client, *ServiceClient.hmac_keys
  use Rack::Idempotent
  run Rack::Client::Handler::NetHTTP
end

Configuration

Exponential Backoff

  • Defaults
    • max_retries = 5
    • min_retry_interval = 0.5 (seconds)
    • max_retry_interval = 1800 (seconds)
Rack::Client.new do
  use Rack::Idempotent, {
    :retry => Rack::Idempotent::ExponentialBackoff.new(
      :max_retries        => 50,
      :min_retry_interval => 1.0,
      :max_retry_interval => 30,
    ),
  }
  use Rack::Lint
  run App
end

Immediate Retry

Rack::Client.new do
  use Rack::Idempotent, {
    :retry => Rack::Idempotent::ImmediateRetry.new(max_retries: 50),
  }
  use Rack::Lint
  run App
end

Running Tests

$ bundle exec rake

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request
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