Rails Omniauth with outbound http proxy

Question

We're trying to use the linkedin-omniauth gem in a Rails application that's behind an http proxy.

I've tried everything I can find to get omniauth to use the proxy but I cannot get it to work.

The following post suggests using:

provider :linkedin, 'xxx', 'xxx', {
  :client_options => {
    :proxy => ENV["HTTP_PROXY"] || ENV["http_proxy"]
  }
}

Which doesn't work for me and I see no mention of 'proxy' in the source. I've also tried hard coding the proxy. No success.

This SO post doesn't work for me either.

I also created an initialiser for net::http with a proxy. That also doesn't work. I've exported the proxy in my shell and bashrc. And in /etc/environment. Nothing's working.

How can I get omniauth to use an outbound proxy?

--- UPDATE ---

Whilst the accepted answer below does indeed work for Linkedin Oauth, most gems now rely on Oauth2. This does away with Net::HTTP and introduces Faraday which has a separate set on rules for the proxy / connection settings:

https://github.com/simonmorley/oauth2/blob/master/lib/oauth2/client.rb#L36

In order to get a proxy working with later gems (inc. popular Facebook, Google, Github check what gem they rely on), you need to use the following in your initialiser:

  provider :foursquare, 'xxx', 'xxx', {
    :client_options => {
      :connection_opts => {
        :proxy => "http://127.0.0.1:3128"
      }
    }
  }

Answer 1

I came across this pull-request from a year ago that fixed the same issue for omniauth-twitter. If you look at the fix, it appears that all they did was change this:

require 'omniauth-oauth'
require 'multi_json'

module OmniAuth
  module Strategies
    class Twitter < OmniAuth::Strategies::OAuth
      option :name, 'twitter'
      option :client_options, {:authorize_path => '/oauth/authenticate',
                               :site => 'https://api.twitter.com'}

to this:

require 'omniauth-oauth'
require 'multi_json'

module OmniAuth
  module Strategies
    class Twitter < OmniAuth::Strategies::OAuth
      option :name, 'twitter'
      option :client_options, {:authorize_path => '/oauth/authenticate',
                               :site => 'https://api.twitter.com',
                       :proxy => ENV['http_proxy'] ? URI(ENV['http_proxy']) : nil}

I assume this sets the oauth "proxy" value parameter that will be passed through the request header. I think if you fork the omniauth-linkedin repo and make a similar change in OmniAuth::Strategies::LinkedIn, it should get you authenticated through the proxy server. I propose a change along the lines of:

require 'omniauth/strategies/oauth'

module OmniAuth
  module Strategies
    class LinkedIn < OmniAuth::Strategies::OAuth
      option :name, "linkedin"

      option :client_options, {
        :site => 'https://api.linkedin.com',
        :request_token_path => '/uas/oauth/requestToken',
        :access_token_path => '/uas/oauth/accessToken',
        :authorize_url => 'https://www.linkedin.com/uas/oauth/authenticate',
        :proxy => ENV['http_proxy'] ? URI(ENV['http_proxy']) : nil
      }

This should convert the environment setting to a URI instance that OmniAuth can consume, parameterize, and properly place in the request.