parse controller API port from apiaddresses in agent.conf

- move flake8 to end of run_tests file, so unit tests always run

run_tests

@@ -11,6 +11,6 @@ if [ -n "$PYTHONPATH" ]; then
 fi
 export PYTHONPATH="src:lib$PYTHONPATH"
 
-flake8
 coverage run --source=src -m unittest -v "$@"
 coverage report -m
+flake8

src/charm.py

@@ -5,13 +5,15 @@
 import controlsocket
 import logging
 import secrets
+import urllib.parse
 import yaml
 from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointProvider
 from ops.charm import CharmBase
 from ops.framework import StoredState
 from ops.charm import RelationJoinedEvent, RelationDepartedEvent
 from ops.main import main
-from ops.model import ActiveStatus, BlockedStatus, Relation
+from ops.model import ActiveStatus, BlockedStatus, ErrorStatus, Relation
+from typing import List
 
 logger = logging.getLogger(__name__)
 
@@ -79,14 +81,20 @@ def _on_metrics_endpoint_relation_created(self, event: RelationJoinedEvent):
         self.control_socket.add_metrics_user(username, password)
 
         # Set up Prometheus scrape config
+        try:
+            api_port = self.api_port()
+        except AgentConfException as e:
+            self.unit.status = ErrorStatus(f"can't read controller API port from agent.conf: {e}")
+            return
+
         metrics_endpoint = MetricsEndpointProvider(
             self,
             jobs=[{
                 "metrics_path": "/introspection/metrics",
                 "scheme": "https",
                 "static_configs": [{
                     "targets": [
-                        f'*:{self.api_port()}'
+                        f'*:{api_port}'
                     ]
                 }],
                 "basic_auth": {
@@ -116,7 +124,16 @@ def _agent_conf(self, key: str):
 
     def api_port(self) -> str:
         """Return the port on which the controller API server is listening."""
-        return self._agent_conf('apiport')
+        api_addresses = self._agent_conf('apiaddresses')
+        if not api_addresses:
+            raise AgentConfException("agent.conf key 'apiaddresses' missing")
+        if not isinstance(api_addresses, List):
+            raise AgentConfException("agent.conf key 'apiaddresses' is not a list")
+
+        parsed_url = urllib.parse.urlsplit('//' + api_addresses[0])
+        if not parsed_url.port:
+            raise AgentConfException("api address doesn't include port")
+        return parsed_url.port
 
     def ca_cert(self) -> str:
         """Return the controller's CA certificate."""
@@ -136,5 +153,9 @@ def generate_password() -> str:
     return secrets.token_urlsafe(16)
 
 
+class AgentConfException(Exception):
+    """Raised when there are errors reading info from agent.conf."""
+
+
 if __name__ == "__main__":
     main(JujuControllerCharm)

tests/test_charm.py

@@ -3,12 +3,36 @@
 
 import os
 import unittest
-from charm import JujuControllerCharm
+from charm import JujuControllerCharm, AgentConfException
+from ops import ErrorStatus
 from ops.testing import Harness
 from unittest.mock import mock_open, patch
 
 agent_conf = '''
-apiport: 17070
+apiaddresses:
+- localhost:17070
+cacert: fake
+'''
+
+agent_conf_apiaddresses_missing = '''
+cacert: fake
+'''
+
+agent_conf_apiaddresses_not_list = '''
+apiaddresses:
+  foo: bar
+cacert: fake
+'''
+
+agent_conf_ipv4 = '''
+apiaddresses:
+- "127.0.0.1:17070"
+cacert: fake
+'''
+
+agent_conf_ipv6 = '''
+apiaddresses:
+- "[::1]:17070"
 cacert: fake
 '''
 
@@ -88,6 +112,54 @@ def test_metrics_endpoint_relation(self, mock_remove_user, mock_add_user,
         harness.remove_relation(relation_id)
         mock_remove_user.assert_called_once_with(f'juju-metrics-r{relation_id}')
 
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf_apiaddresses_missing)
+    def test_apiaddresses_missing(self, _):
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+
+        with self.assertRaisesRegex(AgentConfException, "agent.conf key 'apiaddresses' missing"):
+            harness.charm.api_port()
+
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf_apiaddresses_not_list)
+    def test_apiaddresses_not_list(self, _):
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+
+        with self.assertRaisesRegex(
+            AgentConfException, "agent.conf key 'apiaddresses' is not a list"
+        ):
+            harness.charm.api_port()
+
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf_apiaddresses_missing)
+    @patch("controlsocket.Client.add_metrics_user")
+    def test_apiaddresses_missing_status(self, *_):
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+
+        harness.add_relation('metrics-endpoint', 'prometheus-k8s')
+        self.assertEqual(harness.charm.unit.status, ErrorStatus(
+            "can't read controller API port from agent.conf: agent.conf key 'apiaddresses' missing"
+        ))
+
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf_ipv4)
+    def test_apiaddresses_ipv4(self, _):
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+
+        self.assertEqual(harness.charm.api_port(), 17070)
+
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf_ipv6)
+    def test_apiaddresses_ipv6(self, _):
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+
+        self.assertEqual(harness.charm.api_port(), 17070)
+
 
 class MockBinding:
     def __init__(self, address):