use urllib to parse apiaddress

- test ipv4 and ipv6

src/charm.py

@@ -5,6 +5,7 @@
 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
@@ -129,7 +130,10 @@ def api_port(self) -> str:
         if not isinstance(api_addresses, List):
             raise AgentConfException("agent.conf key 'apiaddresses' is not a list")
 
-        return api_addresses[0].split(':')[-1]
+        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."""

tests/test_charm.py

@@ -24,6 +24,18 @@
 cacert: fake
 '''
 
+agent_conf_ipv4 = '''
+apiaddresses:
+- "127.0.0.1:17070"
+cacert: fake
+'''
+
+agent_conf_ipv6 = '''
+apiaddresses:
+- "[::1]:17070"
+cacert: fake
+'''
+
 
 class TestCharm(unittest.TestCase):
     def test_relation_joined(self):
@@ -132,6 +144,22 @@ def test_apiaddresses_missing_status(self, *_):
             "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):