When binding calls to port 9000 with Akka-HTTP
Http().bindAndHandle(routes, "localhost", 9000)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp6 0 0 127.0.0.1:9000 :::* LISTEN
curl: (7) Failed to connect to 169.254.0.2 port 9000: Connection refused
0.0.0.0 and it will work.
localhost is intended to be used only locally.