Fix 'st2 key load' that errors when importing an empty file

CHANGELOG.rst

@@ -33,6 +33,7 @@ Fixed
   is checked out). (improvement) #4366
 * st2 login now exits with non zero exit code when login fails due to invalid credentials.
   (improvement) #4338
+* Fix ``st2 key load`` that errors when importing an empty file #4393
 
 2.9.0 - September 16, 2018
 --------------------------

st2client/st2client/commands/keyvalue.py

@@ -294,12 +294,16 @@ def run(self, args, **kwargs):
         # load the data (JSON/YAML) from the file
         kvps = resource.load_meta_file(file_path)
 
+        instances = []
+        # bail out if file was empty
+        if not kvps:
+            return instances
+
         # if the data is not a list (ie. it's a single entry)
         # then make it a list so our process loop is generic
         if not isinstance(kvps, list):
             kvps = [kvps]
 
-        instances = []
         for item in kvps:
             # parse required KeyValuePair properties
             name = item['name']

st2client/tests/unit/test_keyvalue.py

@@ -333,3 +333,17 @@ def test_load_keyvalue_bad_file_extension(self):
         finally:
             os.close(fd)
             os.unlink(path)
+
+    def test_load_keyvalue_empty_file(self):
+        """
+        Loading K/V from an empty file shouldn't throw an error
+        """
+        fd, path = tempfile.mkstemp(suffix='.yaml')
+        try:
+            args = ['key', 'load', path]
+            retcode = self.shell.run(args)
+            self.assertIn('No matching items found', self.stdout.getvalue())
+            self.assertEqual(retcode, 0)
+        finally:
+            os.close(fd)
+            os.unlink(path)