tl;dr: I’m proposing to drop Passenger support for Foreman 2.5 and always use Puma.
Context
Since Foreman 2.1 we have defaulted to using Puma instead of Passenger. Originally this was discussed in this RFC:
Back then we said that we want to keep Passenger supported so we can switch back if there are problems. We have happily used that while fixing some gaps in functionality and I’m glad we did, but I believe we have full feature parity now.
That makes me think it’s time to drop Passenger support. This will allow developers to use techniques like websockets (likely via ActionCable) which we weren’t able to support with Passenger but does work with Puma.
Affected projects
There are 3 areas I can think of that are affected:
Packaging
In packaging it means dropping packages. That is easy. In fact, it makes the Ruby 2.7 migration easier if we first drop Passenger because it means we don’t have to rebuild them (and they’re painful to build)
Installer
In the installer we have a --foreman-passenger boolean flag. It would mean dropping that flag and all code to support it. Given that we already have a boolean to switch back and forth, it can already migrate to Puma if any user hasn’t switched.
SELinux
Our SELinux policy has code to support Passenger that can be dropped.
Foreman
In Foreman itself there are some code paths (in particular during initialization) to support Passenger.
Suggested plan & timeline
Completing the removal before Ruby 2.7 makes that migration easier. Since that’s actively worked on, it would make sense to complete this work in the 2.5 timeframe.
A compromise could be to remove it from packaging and the installer but leave the code in core until Foreman 3.0 (planned after Foreman 2.5).
It also means we should add a note to Foreman 2.4 announcing the deprecation.
Unless there are objections, I’d like to proceed with this soon so we are ready well before stablization week is here.