Home Ruby 2.3 - Adding Timeout error and notification to net:http request
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Ruby 2.3 - Adding Timeout error and notification to net:http request

Mathieu
1#
Mathieu Published in 2018-02-02 09:24:47Z

I have a working system to produce errors and send them to be used by Active Admin.

For example in Active admin, for a specific page of our CMS, the page might execute :

url_must_be_accessible("http://www.exmaple.com", field_url_partner, "URL for the partner")

And this uses the code below to send to the Active Admin Editor different type of errors notifications:

module UrlHttpResponseHelper

  def url_must_be_accessible(url, target_field, field_name)      
    if url
      url_response_code = get_url_http_response(url).code.to_i
      case url_response_code
      when -1                                                         
        # DNS issue; website does not exist; 
        errors.add(target_field,
          "#{field_name}: DNS Problem -> #{url} website does not exist")
      when 200
        return 
      when 304
         return
      else
        errors.add(target_field,
          "#{field_name}: #{url} sends #{url_response_code} response code")
      end
    end
  end

  def get_url_http_response(url)  
    uri = URI.parse(URI.encode(url))
    request = Net::HTTP.get_response(uri)
    return request
  rescue Errno::ECONNREFUSED, SocketError => e
    OpenStruct.new(code: -1)
  end

end

In local mode, this worked great! But in production, we're on Heroku and when a request pn Heroku goes beyond 30 seconds like if you try on this link "http://www.exmaple.com", the app crashes with a "H12 error".

I'd like to add to the code above two things - timeouts: i think i need both read_timeout and open_timeout and that the read_timeout + open_timeout should be < to 30 seconds, with let's take some security , better < 25seconds

  • if the request is still "going" after 25 seconds, then avoid reaching 30seconds by giving up/dropping the request

  • and catch this "we dropped the request intentionnally because risk of timeout" by sending a notification to the user. I'd like to use my current system with somehting along the lines of:

     rescue Errno::ECONNREFUSED, SocketError => e
        OpenStruct.new(code: -7) # = some random number
      end
    
    case url_response_code
    when -7
      errors.add(target_field,
              "#{field_name}: We tried to reach #{url} but this takes too long and risks crashing the app. please check the url and try again.")
    

How can I create a code like -1 but another one to rescue this "timeout"/"drop the request attempt" that I myself enforce.

Tried but nothing works. I don't manage to create the code for catch and drop this request if reaches 25 seconds...

nattfodd
2#
nattfodd Reply to 2018-02-05 09:26:01Z

That's not very beautiful solution (see: https://medium.com/@adamhooper/in-ruby-dont-use-timeout-77d9d4e5a001), but I believe you still can use it here, because you only have one thing happening inside opposite to the example in the link, where multiple actions could cause non-obvious behavior:

def get_url_http_response(url)
  uri = URI.parse(URI.encode(url))
  request = Timeout.timeout(25) { Net::HTTP.get_response(uri) }
  return request
rescue Errno::ECONNREFUSED, SocketError => e
  OpenStruct.new(code: -1)
rescue Timeout::Error
  # return here anything you want
end
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