Implement stop and restart of controller/hosts (#554)

Implement remotely initiated stopping and restarting of the controller
and hosts.  Restarting is implemented by exiting with a non-zero exit
code and relying on a process manager to start the procress again.  To
prevent accidentally trying to restart on a system that doesn't have a
process manager present the --can-restart command line option needs to
be passed to enable the restart operation.

packages/controller/src/ControlConnection.ts

@@ -68,6 +68,8 @@ export default class ControlConnection extends BaseConnection {
 			});
 		}
 
+		this.handle(lib.ControllerStopRequest, this.handleControllerStopRequest.bind(this));
+		this.handle(lib.ControllerRestartRequest, this.handleControllerRestartRequest.bind(this));
 		this.handle(lib.ControllerConfigGetRequest, this.handleControllerConfigGetRequest.bind(this));
 		this.handle(lib.ControllerConfigSetFieldRequest, this.handleControllerConfigSetFieldRequest.bind(this));
 		this.handle(lib.ControllerConfigSetPropRequest, this.handleControllerConfigSetPropRequest.bind(this));
@@ -167,6 +169,18 @@ export default class ControlConnection extends BaseConnection {
 		throw new Error("Should be unreachable");
 	}
 
+	async handleControllerStopRequest() {
+		this._controller.stop();
+	}
+
+	async handleControllerRestartRequest() {
+		if (!this._controller.canRestart) {
+			throw new lib.RequestError("Cannot restart, controller does not have a process monitor to restart it.");
+		}
+		this._controller.shouldRestart = true;
+		this._controller.stop();
+	}
+
 	async handleControllerConfigGetRequest() {
 		return this._controller.config.toRemote("control");
 	}