Facebook support

Web authentication flow

This describes the web authentication flow with Facebook. You could also login with an existing access token from Facebook through the API. This web flow sets a cookie, the API returns a JWT instead.

First of all you need to have your API credentials ready by creating an app in the Facebook Dev Center. Then add them to your para-application.conf configuration file:

para-application.conf

para.fb_app_id = "..."
para.fb_secret = "..."

Or add these through the app settings API:

{
  "fb_app_id": "..."
  "fb_secret": "..."
  "signin_success": "http://success.url"
  "signin_failure": "http://failure.url"
}

Para can return a short-lived ID token back to the client which initiated the request. Add jwt=id to your signin_success url. For example { "signin_success": "http://success.url?jwt=id" }. The id value of the parameter will be replaced with the actual JWT ID token, which you can use to call paraClient.signIn("passwordless", idToken) to get the long-lived session token.

Support for logging in with Facebook is implemented by the FacebookAuthFilter. This filter responds to requests at /facebook_auth.

The endpoint expects an appid value from the ‘state’ parameter, e.g. ?state={appid}. If that parameter is missing, the default (root) app will be used as authentication target.

To initiate a login with Facebook just redirect the user to the Facebook OAuth endpoint:

facebook.com/dialog/oauth

Pass the parameter redirect_uri=/facebook_auth so Para can handle the response from Facebook. For apps other than the root app use redirect_uri=/facebook_auth?state=myapp instead.

Register an application

You need to register a new application with Facebook in order to obtain an access and secret keys.

Below is an example Javascript code for a Facebook login button:

$("#facebookLoginBtn").click(function() {
    window.location = "https://www.facebook.com/dialog/oauth?" +
        "response_type=code&client_id={FACEBOOK_APP_ID}" +
        "&scope=email&state=" + APPID +
        "&redirect_uri=" + window.location.origin + "/facebook_auth";
    return false;
});