A Couple Quick Notes

This is not ready for public consumption yet. This is in alpha stage and there are some issues that need to be sorted out before it will be ready for others to use. (i.e. handling gzipped compression). The gzipped compression probably should be handled in hackney (which is what most of the ueberauth strategies use). There is an outstanding issue for this and I'm looking at submitting a PR for this feature.

Secondly - The Stack Exchange API does not return any email address for the user. So if you are wanting to use this to get at that kind of information, you might look else where or plan on asking the user for an email. See this answer.

Überauth StackOverflow

StackOverflow OAuth2 strategy for Überauth.

Installation

1. Setup your application at Stack Apps.

2. Add :ueberauth_stackoverflow to your list of dependencies in mix.exs:

   def deps do
     [{:ueberauth_stackoverflow, "~> 0.0.1"}]
   end

3. Add the strategy to your applications:

   def application do
     [applications: [:ueberauth_stackoverflow]]
   end

4. Add StackOverflow to your Überauth configuration:

   config :ueberauth, Ueberauth,
     providers: [
       stackoverflow: {Ueberauth.Strategy.StackOverflow, []}
     ]

5. Update your provider configuration:

   config :ueberauth, Ueberauth.Strategy.StackOverflow.OAuth,
     client_id: System.get_env("STACKOVERFLOW_CLIENT_ID"),
     client_secret: System.get_env("STACKOVERFLOW_CLIENT_SECRET")

6. Include the Überauth plug in your controller:

   defmodule MyApp.AuthController do
     use MyApp.Web, :controller
   
     pipeline :browser do
       plug Ueberauth
       ...
      end
   end

7. Create the request and callback routes if you haven't already:

   scope "/auth", MyApp do
     pipe_through :browser
   
     get "/:provider", AuthController, :request
     get "/:provider/callback", AuthController, :callback
   end

8. You controller needs to implement callbacks to deal with Ueberauth.Auth and Ueberauth.Failure responses.

For an example implementation see the Überauth Example application.

Calling

Depending on the configured url you can initial the request through:

/auth/stackoverflow

Or with options:

/auth/stackoverflow?scope=no_expiry

By default the requested scope is "". This provides "an application to identify a user via the /me method". See more at StackOverflow's OAuth Documentation. Scope can be configured either explicitly as a scope query value on the request path or in your configuration:

config :ueberauth, Ueberauth,
  providers: [
    stackoverflow: {Ueberauth.Strategy.StackOverflow, [default_scope: "private_info no_expiry"]}
  ]

It is also possible to disable the sending of the redirect_uri to StackOverflow. This is particularly useful when your production application sits behind a proxy that handles SSL connections. In this case, the redirect_uri sent by Ueberauth will start with http instead of https, and if you configured your StackOverflow OAuth application's callback URL to use HTTPS, StackOverflow will throw an uri_missmatch error.

To prevent Ueberauth from sending the redirect_uri, you should add the following to your configuration:

config :ueberauth, Ueberauth,
  providers: [
    stackoverflow: {Ueberauth.Strategy.StackOverflow, [send_redirect_uri: false]}
  ]

License

Please see LICENSE for licensing details.