exmaple.cr

def call(req : HTTP::Request, res : HTTP::Server::Response)
  HTTP::Client.get("/logs") do |log_res|
    stream(res, log_res.body_io) do |r, w|
      r.each_line do |line|
        w.puts "data: #{line}\n\n"
        w.flush
      end
    end
  end
  
  puts "never gets executed"
end

def stream(res, io, heartbeat = 5.seconds, &blk : (IO, IO) ->)
  res.not_nil!.headers["Content-Type"] = "text/event-stream"
  spawn do
    blk.call(io, res)
  end

  while !res.closed?
    res.puts ";ok\n\n"
    res.flush
    sleep heartbeat
  end
rescue
  io.close
end