I'm trying to start Shotgun for a Sinatra app after having upgraded to Ruby 3.0.1, and get this:
$ shotgun
== Shotgun/Thin on http://127.0.0.1:9393/
/Users/me/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/rack-2.2.3/lib/rack/handler/thin.rb:11:in `run': wrong number of arguments (given 2, expected 1) (ArgumentError)
from /Users/me/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/shotgun-0.9.2/bin/shotgun:156:in `<top (required)>'
from /Users/me/.rbenv/versions/3.0.1/bin/shotgun:23:in `load'
from /Users/me/.rbenv/versions/3.0.1/bin/shotgun:23:in `<main>'
Running gem list, I get:
shotgun (0.9.2)
What's going on? Thanks!
Ruby v3.0 introduces a breaking change, relating to keyword vs positional arguments.
The shotgun gem hasn't been updated for a long time; the latest version (0.9.2) was released in September 2016.
Looking at the gem in github, I see there's an open issue about this exact problem you've raised, and someone has already - helpfully - forked the project with a fix.
Unless the original author merges this fix and releases a new version of the gem, you'll need to use a forked version such as the above. For example, update your Gemfile to say:
gem 'shotgun', git: 'https://github.com/delonnewman/shotgun.git'
And then run bundle install.
There's also this open PR with the exact same fix, so you could equally use that fork instead.
... Or alternatively, stick to ruby 2.7 for now.