suppress erros while retrieving worker list

src/ahriman/core/distributed/distributed_system.py

@@ -17,10 +17,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 #
+import contextlib
 import tempfile
 import uuid
 
 from pathlib import Path
+from functools import cached_property
 
 from ahriman.core.configuration import Configuration
 from ahriman.core.configuration.schema import ConfigurationSchema
@@ -36,7 +38,6 @@ class DistributedSystem(Trigger, WebClient):
 
     Attributes:
         identifier_path(Path): path to cached worker identifier
-        worker(Worker): unique self identifier
     """
 
     CONFIGURATION_SCHEMA: ConfigurationSchema = {
@@ -77,8 +78,17 @@ class DistributedSystem(Trigger, WebClient):
             section, "identifier_path", fallback=Path(tempfile.gettempdir()) / "ahriman-worker-identifier")
         self._owe_identifier = False
 
-        identifier = self.load_identifier(configuration, section)
-        self.worker = Worker(configuration.get(section, "address"), identifier=identifier)
+    @cached_property
+    def worker(self) -> Worker:
+        """
+        load and set worker. Lazy property loaded because it is not always required
+
+        Returns:
+            Worker: unique self worker identifier
+        """
+        section = next(iter(self.configuration_sections(self.configuration)))
+        identifier = self.load_identifier(self.configuration, section)
+        return Worker(self.configuration.get(section, "address"), identifier=identifier)
 
     @classmethod
     def configuration_sections(cls, configuration: Configuration) -> list[str]:
@@ -161,10 +171,13 @@ class DistributedSystem(Trigger, WebClient):
         Returns:
             list[Worker]: currently registered workers
         """
-        response = self.make_request("GET", self._workers_url())
-        response_json = response.json()
+        with contextlib.suppress(Exception):
+            response = self.make_request("GET", self._workers_url())
+            response_json = response.json()
 
-        return [
-            Worker(worker["address"], identifier=worker["identifier"])
-            for worker in response_json
-        ]
+            return [
+                Worker(worker["address"], identifier=worker["identifier"])
+                for worker in response_json
+            ]
+
+        return []

src/ahriman/core/distributed/worker_loader_trigger.py

@@ -33,5 +33,8 @@ class WorkerLoaderTrigger(DistributedSystem):
             return  # there is manually set option
 
         workers = [worker.address for worker in self.workers()]
+        if not workers:
+            return
+
         self.logger.info("load workers %s", workers)
         self.configuration.set_option("build", "workers", " ".join(workers))

tests/ahriman/core/distributed/test_distributed_system.py

@@ -159,7 +159,7 @@ def test_unregister_force(distributed_system: DistributedSystem, mocker: MockerF
     remove_mock.assert_called_once_with(missing_ok=True)
 
 
-def test_workers_get(distributed_system: DistributedSystem, mocker: MockerFixture) -> None:
+def test_workers(distributed_system: DistributedSystem, mocker: MockerFixture) -> None:
     """
     must return available remote workers
     """
@@ -174,3 +174,19 @@ def test_workers_get(distributed_system: DistributedSystem, mocker: MockerFixtur
     result = distributed_system.workers()
     requests_mock.assert_called_once_with("GET", distributed_system._workers_url())
     assert result == [worker]
+
+
+def test_workers_failed(distributed_system: DistributedSystem, mocker: MockerFixture) -> None:
+    """
+    must suppress any exception happened during worker extraction
+    """
+    mocker.patch("requests.Session.request", side_effect=Exception())
+    distributed_system.workers()
+
+
+def test_workers_failed_http_error(distributed_system: DistributedSystem, mocker: MockerFixture) -> None:
+    """
+    must suppress HTTP exception happened during worker extraction
+    """
+    mocker.patch("requests.Session.request", side_effect=requests.HTTPError())
+    distributed_system.workers()

tests/ahriman/core/distributed/test_worker_loader_trigger.py

@@ -32,3 +32,16 @@ def test_on_start_skip(configuration: Configuration, mocker: MockerFixture) -> N
     trigger = WorkerLoaderTrigger(repository_id, configuration)
     trigger.on_start()
     run_mock.assert_not_called()
+
+
+def test_on_start_empty_list(configuration: Configuration, mocker: MockerFixture) -> None:
+    """
+    must do not set anything if workers are not available
+    """
+    configuration.set_option("status", "address", "http://localhost:8081")
+    mocker.patch("ahriman.core.distributed.WorkerLoaderTrigger.workers", return_value=[])
+    _, repository_id = configuration.check_loaded()
+
+    trigger = WorkerLoaderTrigger(repository_id, configuration)
+    trigger.on_start()
+    assert not configuration.has_option("build", "workers")