Delegate Flarum login, logout and session validation to an SSO endpoint on the same domain by forwarding the domain-scoped cookies. Main scenario is to share login session between main site and forum site.

Example:

1. SSO url is https://example.com and has login endpoint /api/auth/signin, logout endpoint /api/auth/signout and session endpoint /api/auth/session.
2. Flarum url is https://flarum.example.com with DomainSSO extension enabled.
3. The user clicks Log In on the Flarum site and is redirected to https://example.com/api/auth/signin where they log in and a domain-scoped token cookie is generated.
4. The user is redirected back to Flarum at https://flarum.example.com and the domain-scoped cookie is forwarded to https://example.com/api/auth/session.
5. If based on the domain-scoped cookie the session is validated (returning session JSON) Flarum logs in the user based on the user's email address (the user is created in Flarum's database on first login).
6. The user clicks Log Out on the Flarum site and is logged out of Flarum and is redirected to https://example.com/api/auth/signout where the domain-scoped session is terminated.

Double-clicking Log In on the Flarum site pops up a login dialog for local Flarum admin to login to setup or fix the extension's settings.

Install using composer require glutio/domainsso:*.

Initially the the extension is implemented to work with NextAuth.js and expects the session JSON to have a user property:

{
    "user": {
        "name": "John Doe",
        "email": "john.doe@example.com",
        "image": "https://example.com/image.jpg"
    }
}