promise: Cleanup plugin folder on each run

Promise can appear and disappear, and pyc or pyo files can stay in the folder,
so try hard to remove those stale files.

/reviewed-on !169

slapos/grid/promise/__init__.py

@@ -289,7 +289,6 @@ class PromiseLauncher(object):
         force
           Set to True if force run promises without check their periodicity
     """
-
     self.dry_run = dry_run
     self.__config = {
       'promise-timeout': 20,
@@ -731,6 +730,17 @@ class PromiseLauncher(object):
     success = 0
     if os.path.exists(self.promise_folder) and os.path.isdir(self.promise_folder):
       for promise_name in os.listdir(self.promise_folder):
+        for suffix in ['.pyc', '.pyo']:
+          if promise_name.endswith(suffix):
+            promise_path = os.path.join(self.promise_folder, promise_name)
+            if not os.path.exists(promise_path[:-1]):
+              try:
+                os.unlink(promise_path)
+              except Exception as e:
+                self.logger.warning('Failed to remove %r because of %s', promise_path, e)
+              else:
+                self.logger.debug('Removed stale %r', promise_path)
+
         if promise_name.startswith('__init__') or \
             not promise_name.endswith('.py'):
           continue

slapos/tests/test_promise.py

@@ -1576,6 +1576,18 @@ class TestSlapOSGenericPromise(TestSlapOSPromiseMixin):
     self.assertEqual(result.item.hasFailed(), False)
     self.assertTrue(isinstance(result.item.date, datetime))
 
+  def test_promise_cleanup_plugin_dir(self):
+    stale_pyc = os.path.join(self.plugin_dir, 'stale.pyc')
+    with open(stale_pyc, 'w') as fh:
+     fh.write('')
+    stale_pyo = os.path.join(self.plugin_dir, 'stale.pyo')
+    with open(stale_pyo, 'w') as fh:
+     fh.write('')
+    self.initialisePromise()
+    self.launcher.run()
+    self.assertFalse(os.path.exists(stale_pyc))
+    self.assertFalse(os.path.exists(stale_pyo))
+
   def test_promise_anomaly_disabled(self):
     self.initialisePromise()
     promise_process = self.createPromiseProcess()