Handle FileNotFoundError on current_controller()

Author: DanielArndt

juju/client/connector.py

@@ -5,12 +5,14 @@
 import logging
 
 import macaroonbakery.httpbakery as httpbakery
+
+from juju.client import client
 from juju.client.connection import Connection
 from juju.client.gocookies import GoCookieJar, go_to_py_cookie
-from juju.client.jujudata import FileJujuData, API_ENDPOINTS_KEY
+from juju.client.jujudata import API_ENDPOINTS_KEY, FileJujuData
 from juju.client.proxy.factory import proxy_from_config
-from juju.errors import JujuConnectionError, JujuError, PylibjujuProgrammingError
-from juju.client import client
+from juju.errors import (JujuConnectionError, JujuError,
+                         PylibjujuProgrammingError)
 from juju.version import SUPPORTED_MAJOR_VERSION, TARGET_JUJU_VERSION
 
 log = logging.getLogger('connector')
@@ -113,8 +115,6 @@ async def connect_controller(self, controller_name=None, specified_facades=None)
         """
         if not controller_name:
             controller_name = self.jujudata.current_controller()
-        if not controller_name:
-            raise JujuConnectionError('No current controller')
 
         controller = self.jujudata.controllers()[controller_name]
         endpoints = controller[API_ENDPOINTS_KEY]

juju/client/jujudata.py

@@ -6,11 +6,13 @@
 import os
 import pathlib
 
-from juju.client import client as jujuclient
 import yaml
+
 from juju import tag
+from juju.client import client as jujuclient
 from juju.client.gocookies import GoCookieJar
-from juju.errors import JujuError, PylibjujuProgrammingError
+from juju.errors import (JujuControllerNotFoundError, JujuError,
+                         PylibjujuProgrammingError)
 from juju.utils import juju_config_dir
 
 API_ENDPOINTS_KEY = 'api-endpoints'
@@ -77,7 +79,10 @@ def refresh(self):
 
     def current_controller(self):
         '''Return the current controller name'''
-        return self._load_yaml('controllers.yaml', 'current-controller')
+        try:
+            return self._load_yaml('controllers.yaml', 'current-controller')
+        except FileNotFoundError:
+            raise JujuControllerNotFoundError('No controllers.yaml file found. python-libjuju requires a bootstrapped Juju controller.')
 
     def current_model(self, controller_name=None, model_only=False):
         '''Return the current model, qualified by its controller name.

juju/errors.py

@@ -123,6 +123,10 @@ class JujuModelConfigError(JujuConfigError):
     pass
 
 
+class JujuControllerNotFoundError(JujuError):
+    pass
+
+
 class AbstractMethodError(Exception):
     pass
 

tests/unit/test_jujudata.py

@@ -0,0 +1,19 @@
+# Copyright 2023 Canonical Ltd.
+# Licensed under the Apache V2, see LICENCE file for details.
+
+import unittest
+
+import mock
+import pytest
+
+from juju.client.jujudata import FileJujuData
+from juju.errors import JujuControllerNotFoundError
+
+
+class TestJujuData(unittest.IsolatedAsyncioTestCase):
+    @mock.patch("io.open")
+    async def test_verify_controller_uninitialized(self, mock_io_open):
+        mock_io_open.side_effect = FileNotFoundError()
+        jujudata = FileJujuData()
+        with pytest.raises(JujuControllerNotFoundError):
+            jujudata.current_controller()