Doorkeeper VS warden

The doorkeeper gem.

Take a look at doorkeeper.

Disclosure: I work for FusionAuth.

Depends on what you are looking for.

If you want a standalone auth server, you can use FusionAuth in docker/docker-compose: https://fusionauth.io/docs/v1/tech/installation-guide/docker

You can also package up a library; most major languages have one or more OAuth/OIDC libraries: https://github.com/doorkeeper-gem/doorkeeper for Ruby, https://spring.io/projects/spring-security for Spring/Java, https://oauth2.thephpleague.com/ for PHP, https://pypi.org/project/oauthlib/ for Python.

https://oauth.net/code/ has a further selection of libraries in a variety of languages.

Are there any code examples to implement the PKCE flow in Doorkeeper? I am a bit confused on how to implement it here: https://github.com/doorkeeper-gem/doorkeeper/wiki/Using-PKCE-flow

For authorization we use Doorkeeper gem with PKCE flow.

One thing that is missing from this list is open source language specific libraries. Projects such as https://oauthlib.readthedocs.io/en/latest/oauth2/server.html and https://github.com/doorkeeper-gem/doorkeeper

Depending on your use case, for example if you only have one application, you might be better off running something embedded in your app, or independent but using the same runtime/deployment environment. Then, when you are ready to add another app or integration, you should be able to introduce a standalone auth system more easily if appropriate (because all your auth interactions should be relatively standardized). I'm a big fan of standalone auth systems as a way to simplify access control and give a single view of a user/customer, but you can also succeed using open source embedded libraries.

When the moment comes to introduce a standalone system, you should consider a few dimensions (this list pulled from a previous comment of mine: https://news.ycombinator.com/item?id=26360048 ):

   * open source or not

Devise is an authentication library built on top of Warden, a Rack-based authentication framework.

In general, even though the Hanami ecosystem lacks any "plug-and-play" solutions such as Devise, you can use many existing libraries not tightly coupled to Ruby on Rails. For authentication, you can use Warden, OmniAuth or Rodauth. For uploads there is Shrine. The pagination is built into ROM. Integration with exception catchers such as Rollbar is easy.

There hasn't been a lot that has changed to how sessions are managed. Warden itself hasn't had much by way of updates in years, but you didn't even mention that.

Do you use system tests in authlogic? Devise (or more precisely, Warden) has has a helper that sets the user on next request.

Devise is probably the most popular option out there. If you're learning to apply your skills in the wild then I'd recommend Devise. In my opinion, there's a learning curve, especially if you want to customize it more. You can also learn the underlying Ruby gem called warden.

Warden perhaps? It's the actual authentication part Devise uses.

Despite this approach works, it's polluting the controller with authentication logic. Given that Devise uses Warden under the hood, the same can be achieved by taking advantage of warden callbacks that will always get executed when a meaningful event is triggered.