This library implements a Symfony security firewall listener to authenticate users based on a single query parameter. This is useful for providing one-click login functionality in email and newsletter links.

The library is published as a package and is installable via Composer:

$ composer require jmikola/auto-login

This library requires Symfony 4.3 or above.

This library implements authentication provider and firewall listener classes, which may be plugged into Symfony's security component to intercept requests and automatically authenticate users based on a single request parameter.

To utilize this library in a full-stack Symfony application, you may want to use JmikolaAutoLoginBundle. An example of registering an authentication provider and firewall listener manually may be found in the Security component documentation.

When a user is automatically logged in by a token parameter in the request, they will be authenticated with an AutoLoginToken instance. In the context of authorization, this token satisfies IS_AUTHENTICATED_FULLY. Ideally, it would be possible to restrict the token to IS_AUTHENTICATED_REMEMBERED, but that is not yet supported. Additional information on these authorization levels may be found in Symfony's authorization documentation.

The firewall listener may dispatch events if constructed with an event dispatcher instance.

Upon successful authentication by a token parameter in the request, an interactive login core event will be dispatched with the authenticated AutoLoginToken instance.

This event was contributed by Antonio Trapani in PR #9.

If a token parameter is present in the request, but the user is already authenticated, a custom event will be dispatched, which includes the token's value. After dispatching this event, the listener's default behavior is to return immediately, since there is likely no work to be done.

A practical use for this event would be to mark a user's email addresses as confirmed, assuming the auto-login link with the token was only delivered via email. As a business requirement, the confirmation service might also listen to the interactive login core event and operate when the authenticated token was an AutoLoginToken instance.

Note: Unlike the interactive login event, the token parameter in this event will not have been validated. It will be the responsibility of the listener to check whether it matches the currently authenticated user. For this reason, it may be helpful to inject this library's provider class.

This feature was contributed by Mathieu Gauthier-Lafaye in PR #10.

By default, the listener will only dispatch an event if the user is already authenticated; it does not override the existing authenticated user. In some cases, it may be desirable to allow an auto-login link to override an existing authenticated user. Otherwise, the user would first need to log out before using the auto-login link. Setting the listener's override_already_authenticated boolean option to true will enable this behavior.