Added website relation

The website relation will make it possible to relate the
controller charm to haproxy.

metadata.yaml

@@ -9,3 +9,5 @@ summary: |
 provides:
   dashboard:
     interface: juju-dashboard
+  website:
+    interface: http

requirements.txt

@@ -1 +1,2 @@
 ops
+charmhelpers

src/charm.py

@@ -3,10 +3,13 @@
 # Licensed under the GPLv3, see LICENSE file for details.
 
 import logging
+import os
+import yaml
 
+from charmhelpers.core import hookenv
 from ops.charm import CharmBase
 from ops.main import main
-from ops.model import ActiveStatus
+from ops.model import ActiveStatus, BlockedStatus
 from ops.framework import StoredState
 
 logger = logging.getLogger(__name__)
@@ -21,6 +24,8 @@ def __init__(self, *args):
         self.framework.observe(self.on.start, self._on_start)
         self.framework.observe(
             self.on.dashboard_relation_joined, self._on_dashboard_relation_joined)
+        self.framework.observe(
+            self.on.website_relation_joined, self._on_website_relation_joined)
 
     def _on_start(self, _):
         self.unit.status = ActiveStatus()
@@ -38,6 +43,35 @@ def _on_dashboard_relation_joined(self, event):
             relation.data[self.app]['identity-provider-url'] = self.config['identity-provider-url']
             relation.data[self.app]['is-juju'] = str(self.config['is-juju'])
 
+    def _on_website_relation_joined(self, event):
+        """Connect a website relation."""
+        logger.info("got a new website relation: %r", event)
+        port = api_port()
+        if port is None:
+            logger.error("machine does not appear to be a controller")
+            self.unit.status = BlockedStatus('machine does not appear to be a controller')
+            return
+
+        for relation in self.model.relations['website']:
+            ingress_address = hookenv.ingress_address(relation.id, hookenv.local_unit())
+            relation.data[self.unit]['hostname'] = ingress_address
+            relation.data[self.unit]['private-address'] = ingress_address
+            relation.data[self.unit]['port'] = str(port)
+
+
+def api_port():
+    ''' api_port determines the port that the controller's API server is
+        listening on.  If the machine does not appear to be a juju
+        controller then None is returned.
+    '''
+    machine = os.getenv('JUJU_MACHINE_ID')
+    if machine is None:
+        return None
+    path = '/var/lib/juju/agents/machine-{}/agent.conf'.format(machine)
+    with open(path) as f:
+        params = yaml.safe_load(f)
+    return params.get('apiport')
+
 
 if __name__ == "__main__":
     main(JujuControllerCharm)

tests/__init__.py

@@ -0,0 +1,3 @@
+import ops.testing
+
+ops.testing.SIMULATE_CAN_CONNECT = True

tests/test_charm.py

@@ -1,12 +1,19 @@
 # Copyright 2021 Canonical Ltd.
 # Licensed under the GPLv3, see LICENSE file for details.
 
+import os
 import unittest
+from unittest.mock import patch, mock_open
 
 from ops.testing import Harness
 from charm import JujuControllerCharm
 
 
+agent_conf = '''
+apiport: 17070
+'''
+
+
 class TestCharm(unittest.TestCase):
     def test_relation_joined(self):
         harness = Harness(JujuControllerCharm)
@@ -23,3 +30,22 @@ def test_relation_joined(self):
         self.assertEqual(data["controller-url"], "wss://controller/api")
         self.assertEqual(data["is-juju"], "true")
         self.assertEqual(data.get("identity-provider-url"), None)
+
+    @patch.dict(os.environ, {
+        "JUJU_MACHINE_ID": "machine-0",
+        "JUJU_UNIT_NAME": "controller/0"
+    })
+    @patch("charmhelpers.core.hookenv.ingress_address")
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf)
+    def test_website_relation_joined(self, open, ingress_address):
+        ingress_address.return_value = "192.168.1.17"
+        harness = Harness(JujuControllerCharm)
+        self.addCleanup(harness.cleanup)
+        harness.begin()
+        relation_id = harness.add_relation('website', 'haproxy')
+        harness.add_relation_unit(relation_id, 'haproxy/0')
+
+        data = harness.get_relation_data(relation_id, 'juju-controller/0')
+        self.assertEqual(data["hostname"], "192.168.1.17")
+        self.assertEqual(data["private-address"], "192.168.1.17")
+        self.assertEqual(data["port"], '17070')