Add support for stopping/starting ProcessLogHandler from API

supervisor/components/tfw_init.conf

@@ -4,3 +4,4 @@ directory=/tmp
 command=bash tfw_init.sh
 autorestart=false
 startsecs=0
+priority=1

supervisor/components/tfw_server.conf

@@ -2,3 +2,4 @@
 user=root
 directory=%(ENV_TFW_SERVER_DIR)s
 command=python3 -u tfw_server.py
+priority=2

tfw/components/process_management/process_log_handler.py

@@ -16,17 +16,20 @@ class ProcessLogHandler:
         self._initial_log_tail = log_tail
 
         self.command_handlers = {
-            'process.log.set': self.handle_set
+            'process.log.set': self.handle_set,
+            'process.log.start': self.handle_start,
+            'process.log.stop': self.handle_stop
         }
 
     def start(self):
-        self._monitor = LogInotifyObserver(
-            connector=self.connector,
-            process_name=self.process_name,
-            supervisor_uri=self._supervisor_uri,
-            log_tail=self._initial_log_tail
-        )
-        self._monitor.start()
+        if not self._monitor:
+            self._monitor = LogInotifyObserver(
+                connector=self.connector,
+                process_name=self.process_name,
+                supervisor_uri=self._supervisor_uri,
+                log_tail=self._initial_log_tail
+            )
+            self._monitor.start()
 
     def handle_event(self, message, _):
         try:
@@ -40,5 +43,16 @@ class ProcessLogHandler:
         if data.get('tail'):
             self._monitor.log_tail = data['tail']
 
+    def handle_start(self, _):
+        self.start()
+
+    def handle_stop(self, _):
+        self._stop_monitor()
+
+    def _stop_monitor(self):
+        if self._monitor:
+            self._monitor.stop()
+            self._monitor = None
+
     def cleanup(self):
-        self._monitor.stop()
+        self._stop_monitor()

tfw/fsm/fsm_base.py

@@ -1,6 +1,7 @@
 import logging
 from collections import defaultdict
 from datetime import datetime
+from contextlib import suppress
 
 from transitions import Machine, MachineError
 
@@ -62,14 +63,12 @@ class FSMBase(Machine, CallbackMixin):
         )
 
         if all(predicate_results):
-            try:
+            with suppress(AttributeError, MachineError):
                 from_state = self.state
-                self.trigger(trigger)
-                self.update_event_log(from_state, trigger)
-                return True
-            except (AttributeError, MachineError):
-                LOG.debug('FSM failed to execute nonexistent trigger: "%s"', trigger)
-        return False
+                if self.trigger(trigger):
+                    self.update_event_log(from_state, trigger)
+                    return True
+            LOG.debug('FSM failed to execute nonexistent trigger: "%s"', trigger)
 
     def update_event_log(self, from_state, trigger):
         self.event_log.append({