Fixes #38120 - Use Sinatra 4

[credbbl]

No description provided.

[ekohl]

Not a complete review, but just some things that jumped out to me that helped me understand more.

https://github.com/sinatra/sinatra/blob/main/CHANGELOG.md is helpful and points to https://github.com/rack/rack/blob/main/UPGRADE-GUIDE.md. Now I wonder what else depends on Rack. Probably Rails so we'll need to verify that can also work with Rack 3.

[ekohl]

Note to self: https://github.com/rack/rack/blob/main/UPGRADE-GUIDE.md#binrackup-rackserver-rackhandlerand--racklobster-were-moved-to-a-separate-gem

[ekohl]

Probably Rails so we'll need to verify that can also work with Rack 3.

We're currently on Rails 7.0, but Rails 7.1 added Rack 3 support. That's a blocker to upgrading in our packaging.

[credbbl]

We're currently on Rails 7.0, but Rails 7.1 added Rack 3 support. That's a blocker to upgrading in our packaging.

Where does the proxy use Rails?

[adamruzicka]

Where does the proxy use Rails?

It does not, but foreman does. If foreman and proxy were deployed on the same machine (which they often do), then you'd be able to satisfy the dependencies of only one of them.

[ekohl]

Where does the proxy use Rails?

It doesn't, but https://github.com/theforeman/foreman does. Then in our RPM packaging there is just a single package: https://github.com/theforeman/foreman-packaging/tree/rpm/develop/packages/foreman/rubygem-rack.

Now I'd love to upgrade Rails as well because 7.0 is already EOL and even 7.1 is already EOL: https://endoflife.date/rails. I'm trying to say we need some more coordination.

Last I checked going from 7.0 to 7.1 isn't too hard. According to https://www.fastruby.io/blog/ruby/rails/versions/compatibility-table.html we can still run on Ruby 2.7. Upgrading to 7.2 is harder because it requires us to also bump the minimum Ruby version to 3.1, which is its own can of worms for us. We're working on that, but an area we've neglected for too long.