Überauth Google

Google OAuth2 strategy for Überauth.

Installation

1. Setup your application at Google Developer Console.

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

   def deps do
     [
       {:ueberauth_google, "~> 0.10"}
     ]
   end

3. Add Google to your Überauth configuration:

   config :ueberauth, Ueberauth,
     providers: [
       google: {Ueberauth.Strategy.Google, []}
     ]

4. Update your provider configuration:

   Use that if you want to read client ID/secret from the environment
   variables in the compile time:

   config :ueberauth, Ueberauth.Strategy.Google.OAuth,
     client_id: System.get_env("GOOGLE_CLIENT_ID"),
     client_secret: System.get_env("GOOGLE_CLIENT_SECRET")

   Use that if you want to read client ID/secret from the environment
   variables in the run time:

   config :ueberauth, Ueberauth.Strategy.Google.OAuth,
     client_id: {System, :get_env, ["GOOGLE_CLIENT_ID"]},
     client_secret: {System, :get_env, ["GOOGLE_CLIENT_SECRET"]}

5. Include the Überauth plug in your controller:

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

6. 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

7. Your 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 initiate the request through:

/auth/google

Or with options:

/auth/google?scope=email%20profile

By default the requested scope is “email”. Scope can be configured either explicitly as a scope query value on the request path or in your configuration:

config :ueberauth, Ueberauth,
  providers: [
    google: {Ueberauth.Strategy.Google, [default_scope: "email profile plus.me"]}
  ]

You can also pass options such as the hd parameter to suggest a particular Google Apps hosted domain (caution, can still be overridden by the user), prompt and access_type options to request refresh_tokens and offline access (both have to be present), or include_granted_scopes parameter to allow incremental authorization.

config :ueberauth, Ueberauth,
  providers: [
    google: {Ueberauth.Strategy.Google, [hd: "example.com", prompt: "select_account", access_type: "offline", include_granted_scopes: true]}
  ]

In some cases, it may be necessary to update the user info endpoint, such as when deploying to countries that block access to the default endpoint.

config :ueberauth, Ueberauth,
  providers: [
    google: {Ueberauth.Strategy.Google, [userinfo_endpoint: "https://www.googleapis.cn/oauth2/v3/userinfo"]}
  ]

This may also be set via runtime configuration by passing a 2 or 3 argument tuple. To use this feature, the first argument must be the atom :system, and the second argument must represent the environment variable containing the endpoint url.
A third argument may be passed representing a default value if the environment variable is not found, otherwise the library default will be used.

config :ueberauth, Ueberauth,
  providers: [
    google: {Ueberauth.Strategy.Google, [
      userinfo_endpoint: {:system, "GOOGLE_USERINFO_ENDPOINT", "https://www.googleapis.cn/oauth2/v3/userinfo"}
    ]}
  ]

To guard against client-side request modification, it’s important to still check the domain in info.urls[:website] within the Ueberauth.Auth struct if you want to limit sign-in to a specific domain.

Copyright and License

Copyright (c) 2015 Sean Callan

Released under the MIT License, which can be found in the repository in LICENSE.