How do I configure a Ruby Mechanize agent to work through the Charles web proxy?

Question

I'm writing an "automatically fill in the forms" app using Ruby / Mechanize. It almost works.

I can use the wonderful Charles web proxy to see the exchange between the server and my Firefox browser. Now I want to use Charles to see the exchange between the server and my app.

Charles proxies on port 8888. Assume that the server is at https://my.host.com. One thing that does NOT work is:

@agent ||= Mechanize.new do |agent|
  agent.set_proxy("my.host.com", 8888)
end

This results in a Net::HTTP::Persistent::Error:

...lib/net/http/persistent.rb:579:in `rescue in connection_for': connection refused: my.host.com:8888 (Net::HTTP::Persistent::Error)

So either I'm giving the wrong host argument to agent.set_proxy(host, ...), or I haven't configured Charles properly. (FWIW, I used to be able to do this, but both Mechanize and Charles have matured several generations since those halcyon days...)

Any ideas?

Neil Slater · Accepted Answer · 2015-07-28 06:36:52Z

11

A web proxy is not normally defined by just a port, but is usually a full host name. Charles is very likely installed on localhost. Therefore the following adjustment may work for you:

@agent ||= Mechanize.new do |agent|
  agent.set_proxy("localhost", 8888)
end

edited Jul 28, 2015 at 6:36

answered Aug 21, 2013 at 6:13

Neil Slater

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3 Comments

pguardiario Over a year ago

For the record the tap is unnecessary, Mechanize.new yields itself to the block.

fearless_fool Over a year ago

Thanks -- I should have realized that localhost was the right thing. It almost works -- now all I have to do is get my certificate verify failed errors taken care of. Different problem...

fearless_fool Over a year ago

@pguardiario: thanks for the tip. edited the OP (and my source code) accordingly.

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