Just a short PSA. yesod-auth has shipped with a GoogleEmail module for a while, which used Google's OpenID system to authenticate users via their email addresses. It had the nice property of requiring no configuration to get started, and was therefore included with the scaffolded site as one of two default authentication plugins (Mozilla Persona/BrowserID being the second).
However, Google has begun deprecating their OpenID services. In particular, new sites will no longer be able to use OpenID login already, and all OpenID services will be removed some time next year (IIRC). There are three results of this that Yesod users should be aware of:
- GoogleEmail will no longer be one of the plugins included with the scaffolded site.
- I've released a new version of yesod-auth which includes a new module: GoogleEmail2. This module utilizes the new Google+ login system. The user facing interface is almost identical to what GoogleEmail provides, but you must follow more configuration steps, like getting OAuth credentials from Google. The module documentation contains a list of steps necessary.
- If you have a site that uses GoogleEmail, I recommend you immediately begin testing GoogleEmail2, and role it out ASAP.
GoogleEmail2 has not been very thoroughly tested, so please QA your site before releasing to production. I've already switched over some of my codebases to using it, but that code is not in production yet, so I don't have detailed real-world experience to share.