Proposal: Use Rack::Handler for PreviewServer

[Oleksii Vasyliev]

Hello.

I have idea, but before contribution to it, I need confirm it is good one.

As I can see PreviewServer using webrick (which is logical - no need additional dependency in project). But we can allow end customer to select, which webserver they want to use for preview. As I can see sinatra gem is using Rack::Handler to select best available web server.

I did check, and looks like middleman can work in similar way:

-        @webrick ||= setup_webrick(@options[:debug] || false)

         rack_app = ::Middleman::Rack.new(@app).to_app
-        @webrick.mount '/', ::Rack::Handler::WEBrick, rack_app
+        @server = ::Rack::Handler.get(server_information.server) || ::Rack::Handler.default
+        @server.run rack_app

we can provide ability for user set server from server_information, like [:server] = :puma or ::Rack::Handler.default will try to use best one available - https://github.com/rack/rack/blob/master/lib/rack/handler.rb#L50-L59

Looks like also need more work with server configuration (ssl, logging, etc), that is why I ask if this is good idea before start contributing to it.

Thanks

[Thomas Reynolds]

Seems interesting. I like the inverted control of the server used coming from Rack

[Oleksii Vasyliev]

Thanks @tdreyno I will try make as good as possible PR for this change