Class: ProxyRole

Inherits:
Role
  • Object
show all
Defined in:
lib/proxy_role.rb

Constant Summary collapse

PORT = 
9400
ESI_MATCH = 
/<esi:try>.*?<esi:attempt>.*?<esi:include src="([^"]+)" ?\/>.*?<\/esi:attempt>.*?<esi:except>(.*?)<\/esi:except>.*?<\/esi:try>/m

Constants inherited from Role

Role::INDEX

Instance Method Summary collapse

Methods inherited from Role

#disable_link, #enable_link, get_role, #init_links, role, #state

Constructor Details

#initialize(manifest) ⇒ ProxyRole

Returns a new instance of ProxyRole.



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# File 'lib/proxy_role.rb', line 9

def initialize(manifest)
  super
  init_links 'backends', @manifest['backends']
  init_links 'stats_backends', @manifest['stats_backends']
end

Instance Method Details

#choose_backend(request) ⇒ Object 



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# File 'lib/proxy_role.rb', line 15

def choose_backend(request)
  url = request.match(/^[A-Z]+ (.*?) HTTP/)[1]
  case url
  when /^\/stats/
    addr = @active_links['stats_backends'].sort_by { rand }.pop
    [addr, StatsRole::PORT] if addr
  else
    addr = @active_links['backends'].sort_by { rand }.pop
    [addr, RailsRole::PORT] if addr
  end
end

#handle_esi(body) ⇒ Object 



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# File 'lib/proxy_role.rb', line 29

def handle_esi(body)
  body.gsub(ESI_MATCH) do |match|
    url = $1
    otherwise = $2

    html = simulate_request($1) || ''
    html.strip.size > 0 ? html : otherwise
  end
end

#simulate_request(url) ⇒ Object 



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# File 'lib/proxy_role.rb', line 39

def simulate_request(url)
  puts "Simulating request to #{url}"
  Net::HTTP.get(URI.parse("http://127.0.0.1:#{PORT}#{url}"))
end

#start ⇒ Object Also known as: enable 



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# File 'lib/proxy_role.rb', line 44

def start
  @server_thread = Thread.new {
    @proxy_server = TCPServer.new('0.0.0.0', PORT)
    loop do
      Thread.new(@proxy_server.accept) { |client_sock|
        begin
          request = client_sock.recv(16384)

          backend_addr = choose_backend(request)
          if backend_addr
            backend_sock = TCPSocket.new(*backend_addr)

            backend_sock.send(request, 0)

            first_blob = backend_sock.recv(16384)
            headers, body = first_blob.split("\r\n\r\n")
            body ||= ''

            match = headers.match(/Content-Length: (\d+)/)
            content_length = match ? match[1].to_i : 0

            if content_length > 0
              if content_length > body.size
                body << backend_sock.recv(content_length - body.size)
              end

              processed_body = handle_esi(body)

              real_length = processed_body.size
              processed_headers = headers.gsub(/Content-Length: (\d+)/, "Content-Length: #{real_length}")

              client_sock.send(processed_headers, 0)
              client_sock.send("\r\n\r\n", 0)
              client_sock.send(processed_body, 0)
            else
              client_sock.send(first_blob,0)
            end
          else
            # no available backend ; send a 503
            client_sock.send "HTTP/1.1 503 Service Unavailable\r\n\r\n", 0
          end
        rescue Errno::ECONNREFUSED, Errno::ECONNABORTED
          # no available backend ; send a 503
          client_sock.send "HTTP/1.1 503 Service Unavailable\r\n\r\n", 0
        ensure
          backend_sock.close if backend_sock
          client_sock.close if client_sock
        end
      }
    end
  }

  #health_check
end

#stop ⇒ Object Also known as: disable 



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# File 'lib/proxy_role.rb', line 99

def stop
  begin
    @proxy_server.shutdown if @proxy_server
  rescue Errno::ENOTCONN
  end
  @server_thread.kill if @server_thread
  @health_thread.kill if @health_thread
end