Agent: Add block parameter to IMaster.terminate()

This allows the caller to decide whether or not they're willing to wait
for the master to finish shutting down.

monkey/infection_monkey/i_master.py

@@ -10,9 +10,10 @@ class IMaster(metaclass=abc.ABCMeta):
         """
 
     @abc.abstractmethod
-    def terminate(self) -> None:
+    def terminate(self, block: bool = False) -> None:
         """
         Stop the master and interrupt any actions that are currently being executed.
+        :param bool block: Whether or not to block and wait for the master to terminate.
         """
 
     @abc.abstractmethod

monkey/infection_monkey/master/automated_master.py

@@ -52,12 +52,15 @@ class AutomatedMaster(IMaster):
         self._master_thread.join()
         logger.info("The simulation has been shutdown.")
 
-    def terminate(self):
+    def terminate(self, block: bool = False):
         logger.info("Stopping automated breach and attack simulation")
         self._stop.set()
 
-        if self._master_thread.is_alive():
+        if self._master_thread.is_alive() and block:
             self._master_thread.join()
+            # We can only have confidence that the master terminated successfully if block is set
+            # and join() has returned.
+            logger.info("AutomatedMaster successfully terminated.")
 
     def _run_master_thread(self):
         self._simulation_thread.start()

monkey/infection_monkey/master/mock_master.py

@@ -124,7 +124,7 @@ class MockMaster(IMaster):
         self._telemetry_messenger.send_telemetry(FileEncryptionTelem(path, success, error))
         logger.info("Finished running payloads")
 
-    def terminate(self) -> None:
+    def terminate(self, block: bool = False) -> None:
         logger.info("Terminating MockMaster")
 
     def cleanup(self) -> None: