An Easter Egg for Curl

Daniel Doubrovkine

@dblockdotorg

Let's implement an Easter egg that requires curl and is HTTP-compliant.

We accept access tokens on our API endpoints. These can come from an access_token query string parameter.

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curl https://api.artsy.net/api/v1/system/up?access_token=invalid -v

< HTTP/1.1 401 Unauthorized
< Content-Type: application/json
< Content-Length: 24

{ "error" : "Unauthorized" }

So far, so good. Now try this:

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curl https://api.artsy.net/api/v1/system/up?access_token=10013 -v

< HTTP/1.1 401 Broadway
< Content-Type: application/json
< Content-Length: 76

{ "error" : "Inspiration from the Engineering team at http://artsy.github.com" }

What?! 401 Broadway? See, our office address is 401 Broadway, 10013, New York, NY. We just tried to add a more developer-friendly way to find us in the New York grid. And here's the view from our 25th floor office - that's SOHO right below us and the Empire State Building a bit North.

Photo by @zamiang.

Easter egg implementation follows.

Implementing a custom HTTP response is surprisingly hard with most web servers. Changing the text that follows error codes is not something most people need. Our API will have to return a custom error code and some monkey-patching will translate the status message. We use grape, which is Rack-based and supports inserting middleware, where we do authentication. We randomly chose the number 2600 for an internal status code.

api/api_action_dispatch_request.rb
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class ApiActionDispatchRequest < ActionDispatch::Request

  def initialize(env)
    super(env)
  end

  def [](key)
    params[key] || headers["X_#{key.to_s.upcase}"]
  end

end
api/api_auth_middleware.rb
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class ApiAuthMiddleware < Grape::Middleware::Base

  def before
    if access_token == "10013"
      throw :error,
        message: 'Inspiration from the Engineering team at http://artsy.github.com',
        status: 2600
    else
      ...
    end
  end

  private

    def access_token
      @access_token ||= request[:access_token]
    end

    def request
      @request ||= ApiActionDispatchRequest.new(env)
    end

end

WEBrick

config/initializers/broadway/webrick.rb
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module WEBrick
  class HTTPResponse
    def status=(status)
      if status == 2600
        @status = 401
        @reason_phrase = "Broadway"
      else
        @status = status
        @reason_phrase = HTTPStatus::reason_phrase(status)
      end
    end
  end
end

Thin

config/initializers/broadway/thin.rb
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module Thin
  class Response
    def head
      if @status == 2600
        "HTTP/1.1 401 Broadway\r\n#{headers_output}\r\n"
      else
        "HTTP/1.1 #{@status} #{HTTP_STATUS_CODES[@status.to_i]}\r\n#{headers_output}\r\n"
      end
    end
  end
end

Unicorn

config/initializers/broadway/unicorn.rb
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require 'unicorn/http_response'
module Unicorn::HttpResponse
  CODES[2600] = '401 Broadway'
end

More Eggs?

Check out artsy.net/humans.txt for more Easter eggs and please feel free to email me at db[at]artsy[dot]net if you want to come visit or work here.

Posted by
Daniel Doubrovkine
Site GitHub @dblockdotorg

Categories: easter eggs, fun

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