Bind to unix socket

[doits]

Is it possible to bind to a unix socket? I have this falcon.rb:

#!/usr/bin/env -S falcon host
# frozen_string_literal: true

# Force to always use threads instead of processes/forks
module Falcon
  module Command
    class Host
      def container_class
        Async::Container::Threaded
      end
    end
  end
end

load :rack

hostname = File.basename(__dir__)

rack hostname do
  endpoint Async::HTTP::Endpoint.parse('http://localhost:3000').with(protocol: Async::HTTP::Protocol::HTTP1)
end

I tried ...

endpoint Async::HTTP::Endpoint.parse('unix://./tmp_something').with(protocol: Async::HTTP::Protocol::HTTP1)

... but I get:

 0.03s    error: Async::Task [oid=0x1568] [ec=0x157c] [pid=62343] [2021-06-16 23:09:27 +0200]
               |   SocketError: getaddrinfo: nodename nor servname provided, or not known
               |   → /.rbenv/versions/2.7.3/lib/ruby/2.7.0/socket.rb:227 in `getaddrinfo'
               |     /.rbenv/versions/2.7.3/lib/ruby/2.7.0/socket.rb:227 in `foreach'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/async-io-1.32.1/lib/async/io/host_endpoint.rb:89 in `each'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/async-http-0.56.3/lib/async/http/endpoint.rb:207 in `each'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/async-io-1.32.1/lib/async/io/endpoint.rb:102 in `bound'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/async-io-1.32.1/lib/async/io/shared_endpoint.rb:31 in `bound'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/falcon-0.39.1/lib/falcon/service/application.rb:68 in `block in start'
               |     /.rbenv/versions/2.7.3/lib/ruby/gems/2.7.0/gems/async-1.29.0/lib/async/task.rb:263 in `block in make_fiber'

Is there a way to bind to a socket?

[ioquatix]

Yes, that's the default:

falcon/lib/falcon/environments/application.rb

Lines 51 to 63 in 4211499

	# The IPC path to use for communication with the application.
	# @attribute [String]
	ipc_path {::File.expand_path("application.ipc", root)}
	# The endpoint that will be used for communicating with the application server.
	# @attribute [Async::IO::Endpoint]
	endpoint do
	::Falcon::ProxyEndpoint.unix(ipc_path,
	protocol: protocol,
	scheme: scheme,
	authority: authority
	)
	end

[doits]

Thanks, got it working with the following:

#!/usr/bin/env -S falcon host
# frozen_string_literal: true

# always force threads instead of processes/forks
Falcon::Command::Host.prepend(
  Module.new do
    def container_class
      Async::Container::Threaded
    end
  end
)

load :rack

hostname = File.basename(__dir__)

rack hostname do
  endpoint ::Falcon::ProxyEndpoint.unix(
    ::File.expand_path('tmp/sockets/falcon', root),
    scheme: 'http',
    protocol: Async::HTTP::Protocol::HTTP1
  )
end

[ioquatix]

always force threads instead of processes/forks

What is the reason for this?

[doits]

My app works fine in multiple threads but not with multiple forks/processes, because it uses a custom in memory cache store, which additionally might be altered during runtime. With different processes it is not shared and can lead to different results depending on what process answers the request. That's why I am forcing it to threads for now until the app is refactored to not use such kind of store, or do you see another solution?

[ioquatix]

I would suggest using https://github.com/socketry/async-redis as a cache backend.

[uberjay]

Thanks for this -- I have a relatively small application that falcon is a good fit for (previously I have used EventMachine, but was really not excited about dusting off a huge stack of old async ruby software). Ideally, deployment wouldn't require installing additional services. (iow, no redis).

So far i've just set the application instance to 1 to ensure multiple processes were not started, but hacking falcon to always use a threaded model is better. How would you feel about exposing this as a configuration parameter in the application configuration?