# Überauth Google [](https://hex.pm/packages/ueberauth_google)
> Google OAuth2 strategy for Überauth.
## Installation
1. Setup your application at [Google Developer Console](https://console.developers.google.com/home).
1. Add `:ueberauth_google` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:ueberauth_google, "~> 0.10"}]
end
```
1. Add the strategy to your applications:
```elixir
def application do
[applications: [:ueberauth_google]]
end
```
1. Add Google to your Überauth configuration:
```elixir
config :ueberauth, Ueberauth,
providers: [
google: {Ueberauth.Strategy.Google, []}
]
```
1. Update your provider configuration:
Use that if you want to read client ID/secret from the environment
variables in the compile time:
```elixir
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:
```elixir
config :ueberauth, Ueberauth.Strategy.Google.OAuth,
client_id: {System, :get_env, ["GOOGLE_CLIENT_ID"]},
client_secret: {System, :get_env, ["GOOGLE_CLIENT_SECRET"]}
```
1. Include the Überauth plug in your controller:
```elixir
defmodule MyApp.AuthController do
use MyApp.Web, :controller
plug Ueberauth
...
end
```
1. Create the request and callback routes if you haven't already:
```elixir
scope "/auth", MyApp do
pipe_through :browser
get "/:provider", AuthController, :request
get "/:provider/callback", AuthController, :callback
end
```
1. Your controller needs to implement callbacks to deal with `Ueberauth.Auth` and `Ueberauth.Failure` responses.
For an example implementation see the [Überauth Example](https://github.com/ueberauth/ueberauth_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:
```elixir
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](https://developers.google.com/identity/protocols/oauth2/web-server#incrementalAuth).
```elixir
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.
```elixir
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.
```elixir
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.
## License
Please see [LICENSE](https://github.com/ueberauth/ueberauth_google/blob/master/LICENSE) for licensing details.
