Why is there wrong number of arguments error when using the Thin gem v1.8.2 with Ruby 3.0.4?

Question

When using Thin gem v1.8.2 with Ruby v3.0.4, there is an argument error for the wrong number of arguments (given 2, expected 1). It appears that the Rack::Handler class was introduced in Thin v1.8.0. The following shows the error that I am getting.

List of Gems:

• rake 13.0.6
• public_suffix 5.0.1
• bundler 2.4.12
• httpclient 2.8.3
• io-console 0.6.0
• json 2.6.3
• matrix 0.4.2
• racc 1.6.2
• nio4r 2.5.9
• rack 2.2.6.4
• ruby_expect 1.7.5
• rubyzip 1.3.0
• snmp 1.3.2
• uuidtools 2.2.0
• yard 0.9.34
• connection_pool 2.4.0
• faraday-net_http 3.0.2
• ruby2_keywords 0.0.5
• ffi 1.15.5
• tilt 2.1.0
• multi_json 1.15.0
• daemons 1.4.1
• eventmachine 1.2.7
• ruby-termios 1.1.0
• addressable 2.8.4
• reline 0.3.3
• nokogiri 1.14.3 (x86_64-linux)
• puma 5.6.5
• faraday 2.7.4
• mustermann 3.0.0
• faraday-retry 2.1.0
• ethon 0.16.0
• irb 1.6.4
• em-websocket 0.3.8
• debug 1.7.2
• rack-protection 3.0.6
• thin 1.8.2
• typhoeus 1.4.0
• sinatra 3.0.6
• sinatra-websocket 0.3.1
• faraday-typhoeus 1.0.0
• sinatra-contrib 3.0.6

Stack Trace:

2023-04-25 09:54:45 #<Thread:0x00007fbaaafbd328 /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/middleware.rb:82 run> terminated with exception (report_on_exception is true):
2023-04-25 09:54:45 /opt/app-root/src/.local/share/gem/ruby/gems/faraday-typhoeus-1.0.0/lib/faraday/adapter/typhoeus.rb:91:in `block in request': Couldn't connect to server (Faraday::ConnectionFailed)
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/callbacks.rb:146:in `block in execute_callbacks'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/callbacks.rb:145:in `each'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/callbacks.rb:145:in `execute_callbacks'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/operations.rb:35:in `finish'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/easy_factory.rb:164:in `block in set_callback'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/ethon-0.16.0/lib/ethon/easy/response_callbacks.rb:74:in `block in complete'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/ethon-0.16.0/lib/ethon/easy/response_callbacks.rb:74:in `each'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/ethon-0.16.0/lib/ethon/easy/response_callbacks.rb:74:in `complete'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/ethon-0.16.0/lib/ethon/easy/operations.rb:34:in `perform'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/operations.rb:16:in `run'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/cacheable.rb:18:in `run'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/block_connection.rb:31:in `run'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/stubbable.rb:25:in `run'
2023-04-25 09:54:45 2023/04/25 15:54:45.090 DEBUG: Middleware Logger is set up to record debugging messages
2023-04-25 09:54:45 2023/04/25 15:54:45.090 INFO: My Middleware creating a connection to CTS API at dev-base:5000
2023-04-25 09:54:45 2023/04/25 15:54:45.090 INFO: Main Middleware has finished initialization
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/typhoeus-1.4.0/lib/typhoeus/request/before.rb:26:in `run'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-typhoeus-1.0.0/lib/faraday/adapter/typhoeus.rb:48:in `perform_request'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-typhoeus-1.0.0/lib/faraday/adapter/typhoeus.rb:28:in `call'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-retry-2.1.0/lib/faraday/retry/middleware.rb:149:in `call'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-2.7.4/lib/faraday/rack_builder.rb:153:in `build_response'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-2.7.4/lib/faraday/connection.rb:444:in `run_request'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/faraday-2.7.4/lib/faraday/connection.rb:280:in `post'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/cts_api.rb:102:in `block in handle_inside_pool'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/connection_pool-2.4.0/lib/connection_pool.rb:107:in `block (2 levels) in with'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/connection_pool-2.4.0/lib/connection_pool.rb:106:in `handle_interrupt'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/connection_pool-2.4.0/lib/connection_pool.rb:106:in `block in with'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/connection_pool-2.4.0/lib/connection_pool.rb:103:in `handle_interrupt'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/connection_pool-2.4.0/lib/connection_pool.rb:103:in `with'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/cts_api.rb:101:in `handle_inside_pool'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/cts_api.rb:67:in `handle_post'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/utilities/cts_log_reader.rb:159:in `server_message_log_filename'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/utilities/cts_log_reader.rb:52:in `start_populating_source'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/utilities/cts_log_reader.rb:44:in `initialize'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/middleware.rb:82:in `new'
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/lib/middleware.rb:82:in `block in <class:MiddlewareApp>'
2023-04-25 09:54:45 bundler: failed to load command: main-middleware (/opt/app-root/src/bin/main-middleware)
2023-04-25 09:54:45 /opt/app-root/src/.local/share/gem/ruby/gems/thin-1.8.2/lib/rack/handler/thin.rb:11:in `run': wrong number of arguments (given 2, expected 1) (ArgumentError)
2023-04-25 09:54:45     from /opt/app-root/src/.local/share/gem/ruby/gems/my-middleware-1.1.4/bin/main-middleware:33:in `<top (required)>'
2023-04-25 09:54:45     from /opt/app-root/src/bin/main-middleware:25:in `load'
2023-04-25 09:54:45     from /opt/app-root/src/bin/main-middleware:25:in `<top (required)>'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli/exec.rb:58:in `load'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli/exec.rb:58:in `kernel_load'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli/exec.rb:23:in `run'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli.rb:479:in `exec'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli.rb:31:in `dispatch'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/cli.rb:25:in `start'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/libexec/bundle:49:in `block in <top (required)>'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/lib/bundler/friendly_errors.rb:103:in `with_friendly_errors'
2023-04-25 09:54:45     from /usr/share/gems/gems/bundler-2.2.33/libexec/bundle:37:in `<top (required)>'
2023-04-25 09:54:45     from /usr/bin/bundle:23:in `load'
2023-04-25 09:54:45     from /usr/bin/bundle:23:in `<main>'

After doing some more digging (given the clue in comments from Tom Lord and Todd Jacobs), I think I found the cause and solution. The run method for Rack::Handler::Thin class accepts a keyword argument and could be called with a hash in Ruby 2.7. But with the changes in Ruby 3.0, it appears that this is no longer allowed.

Before (ArgumentError):

myOptions = {
  Host: myHost,
  Port: myPort
}

Rack::Handler::Thin.run(MyApp, options=myOptions) <<-- no splat, hash arg

After (No Errors):

myOptions = {
  Host: myHost,
  Port: myPort
}

Rack::Handler::Thin.run(MyApp, **options=myOptions) <<-- dbl splat, hash arg