Don't start Synapse master process if `worker_app` is set (#11416)

* Add check to catch syanpse master process starting when workers are configured

* add test to verify that starting master process with worker config raises error

* newsfragment

* specify config.worker.worker_app in check

* update test

* report specific config option that triggered the error

Co-authored-by: reivilibre <oliverw@matrix.org>

* clarify error message

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/tests/app/test_homeserver_start.py b/tests/app/test_homeserver_start.py
new file mode 100644
index 0000000000..cbcada0451
--- /dev/null
+++ b/tests/app/test_homeserver_start.py
@@ -0,0 +1,31 @@
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import synapse.app.homeserver
+from synapse.config._base import ConfigError
+
+from tests.config.utils import ConfigFileTestCase
+
+
+class HomeserverAppStartTestCase(ConfigFileTestCase):
+    def test_wrong_start_caught(self):
+        # Generate a config with a worker_app
+        self.generate_config()
+        # Add a blank line as otherwise the next addition ends up on a line with a comment
+        self.add_lines_to_config(["  "])
+        self.add_lines_to_config(["worker_app: test_worker_app"])
+
+        # Ensure that starting master process with worker config raises an exception
+        with self.assertRaises(ConfigError):
+            synapse.app.homeserver.setup(["-c", self.config_file])