It would be nice if Guacamole had OAuth2 authentication plugin.
OAuth2 is wide spread in web technologies and Guacamole deserves to have its implementation of the protocol.
My company had this use case and for now we are using a custom authentication plugin because implementing a generic OAuth2 compatible Guacamole authentication plugin presents some difficulties.
OAuth2 requires clients (Guacamole in our case) to register a redirect URI so that the OAuth2 server could callback the application when the user has been identify (or rejected) on its side. It also passes along some informations like tokens or reason of failure as part of the URL. If we set the Guacamole index URL as the redirect URI then this data never get passed along to the authenticate plugin.
Such redirect URI cannot contain any pound sign (#) because this sign in a URI is a delimiter after which data are not sent to the server on HTTP request. In the case of Guacamole, the Angular frontend uses those local URI data to determine which page to display.
Angular behavior cannot be easilly turned off and would lead to heaver code changes and uncompatibility with older browser.
Connection list is retrieved at user login. It doesn't make sense to expect the OAuth server to give such list as it would not be generic enough.
Fortunatly, connection lists get merged between authentication plugins and this OAuth plugin could be paired with another one which goal would just be to provide the connection list.
Upon a successful authentication, the OAuth2 server will issued an auth token.
First, this token needs to be invalidated by Guacamole when user explicitly disconnects.
Second, there is no way for Guacamole to know if a stored auth token is still valid. Leaving the user to freely keep on using its Guacamole session even thought the token has expired.
I am just leaving these though here so the Guacamole community could start an discussion on this matter.