Disable mdns polkadot (#58)

Deactivate mdns for polkadot node as it prevents the process to exit properly

Fixes #57

cumulus/test/parachain/tests/polkadot_mdns_issue.rs

@@ -0,0 +1,48 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use assert_cmd::cargo::cargo_bin;
+use std::{convert::TryInto, process::Command, thread, time::Duration, fs};
+
+mod common;
+
+#[test]
+#[cfg(unix)]
+fn interrupt_polkadot_mdns_issue_test() {
+	use nix::sys::signal::{kill, Signal::{self, SIGINT, SIGTERM}};
+	use nix::unistd::Pid;
+
+	fn run_command_and_kill(signal: Signal) {
+		let _ = fs::remove_dir_all("interrupt_polkadot_mdns_issue_test");
+		let mut cmd = Command::new(cargo_bin("cumulus-test-parachain-collator"))
+			.args(&["-d", "interrupt_polkadot_mdns_issue_test"])
+			.spawn()
+			.unwrap();
+
+		thread::sleep(Duration::from_secs(20));
+		assert!(cmd.try_wait().unwrap().is_none(), "the process should still be running");
+		kill(Pid::from_raw(cmd.id().try_into().unwrap()), signal).unwrap();
+		assert_eq!(
+			common::wait_for(&mut cmd, 30).map(|x| x.success()),
+			Some(true),
+			"the process must exit gracefully after signal {}",
+			signal,
+		);
+	}
+
+	run_command_and_kill(SIGINT);
+	run_command_and_kill(SIGTERM);
+}