Facebook External Authentication is a fast and convenient way for people to create accounts and log into online store. In GrandNode it's a plugin available out of the box, so you are able to use it immediately after GrandNode installation.
To configure facebook authentication:
1. Navigate to the Facebook for Developers page and sign in. If you don't already have a Facebook account, use the Sign up for Facebook link on the login page to create one.
2. Tap the + Add a New App button in the upper right corner to create a new App ID. (If this is your first app with Facebook, the text of the button will be Create a New App.)
3. Fill out the form and tap the Create App ID button.
4. The Product Setup page is displayed, letting you select the features for your new app. Click Get Started on Facebook Login.
5. Click the Settings link in the menu at the left, you are presented with the Client OAuth Settings page with some defaults already set.
6. Enter "https://yourstore.com/signin-facebook" into the Valid OAuth Redirect URIs field.
7. Click Save Changes.
8. Click the Dashboard link in the left navigation.
9. Copy your App ID and App secret below.
What's important. You need to configure SSL in your store to ensure customer data security. Without https:// in your URL, you will receive error message during the login process.