Use the latest framework code + fix race condition

README.md

@@ -25,9 +25,6 @@ all units is possible to configure via the relevant config options.
 
 # Deploy
 
-Note: The charm currently depends on this to-be-merged PR https://github.com/canonical/operator/pull/109
-for working with network spaces.
-
 ```bash
 juju deploy --resource nats=<path-to-nats-snap-file> <nats-charm-dir>
 ```

src/charm.py

@@ -4,6 +4,7 @@
 import string
 import random
 import sys
+import logging
 sys.path.append('lib') # noqa
 
 from ops.charm import CharmBase, CharmEvents
@@ -23,6 +24,9 @@
 from cryptography.x509 import load_pem_x509_certificate
 
 
+logger = logging.getLogger(__name__)
+
+
 class NatsStartedEvent(EventBase):
     pass
 
@@ -79,6 +83,7 @@ def on_install(self, event):
         if nats_res is not None and Path(nats_res).stat().st_size:
             nats_cmd = cmd + ['--dangerous', nats_res]
         subprocess.check_call(nats_cmd)
+        subprocess.check_call(['snap', 'stop', 'nats', '--disable'])
         self.SERVER_PATH.mkdir(exist_ok=True, mode=0o0700)
 
     def handle_tls_config(self):
@@ -112,6 +117,7 @@ def handle_tls_config(self):
                 self.client.set_tls_ca(tls_ca_cert)
 
     def reconfigure_nats(self):
+        logger.info('Reconfiguring NATS')
         self.handle_tls_config()
         ctxt = {
             'client_port': self.model.config['client-port'],
@@ -140,10 +146,12 @@ def reconfigure_nats(self):
         content_hash = hash(rendered_content)
         old_hash = self.state.nats_config_hash
         if old_hash != content_hash:
+            logging.info(f'Config has changed - re-rendering a template to {self.NATS_SERVER_CONFIG_PATH}')
+            logger.info('')
             self.state.rendered_content_hash = content_hash
             self.NATS_SERVER_CONFIG_PATH.write_text(rendered_content)
             if self.state.is_started:
-                subprocess.check_call(['systemctl', 'restart', f'{self.NATS_SERVICE}'])
+                subprocess.check_call(['systemctl', 'restart', self.NATS_SERVICE])
         self.client.expose_nats()
 
     def get_auth_token(self, length=None):
@@ -155,10 +163,7 @@ def get_auth_token(self, length=None):
         return ''.join([rng.choice(alphanumeric_chars) for _ in range(length)])
 
     def on_start(self, event):
-        if not self.cluster.is_joined and not self.model.config['listen-on-all-addresses']:
-            event.defer()
-            return
-        subprocess.check_call(['systemctl', 'start', f'{self.NATS_SERVICE}'])
+        subprocess.check_call(['snap', 'start', 'nats', '--enable'])
         self.state.is_started = True
         self.on.nats_started.emit()
         self.model.unit.status = ActiveStatus()
@@ -170,9 +175,6 @@ def on_client_relation_joined(self, event):
         self.reconfigure_nats()
 
     def on_config_changed(self, event):
-        if not self.cluster.is_joined and not self.model.config['listen-on-all-addresses']:
-            event.defer()
-            return
         self.reconfigure_nats()
 
     def on_upgrade_charm(self, event):

src/interfaces.py

@@ -34,7 +34,7 @@ def peer_addresses(self):
     @property
     def listen_address(self):
         if self._listen_address is None:
-            self._listen_address = self.model.get_binding(self.relation).network.bind_address
+            self._listen_address = self.model.get_binding(self._relation_name).network.bind_address
         return self._listen_address
 
 
@@ -55,17 +55,17 @@ def __init__(self, charm, relation_name, listen_on_all_addresses, client_port):
     @property
     def listen_address(self):
         if self._listen_address is None:
-            addresses = []
+            addresses = set()
             for relation in self.model.relations[self._relation_name]:
                 address = self.model.get_binding(relation).network.bind_address
-                if address not in addresses:
-                    addresses.append(address)
+                addresses.add(address)
             if len(addresses) > 1:
                 raise Exception('Multiple potential listen addresses detected: NATS does not support that')
             elif addresses == 1:
-                self._listen_address = addresses[0]
+                self._listen_address = addresses.pop()
             else:
-                self._listen_address = ipaddress.ip_address('127.0.0.1')
+                # Default to network information associated with an endpoint binding itself in absence of relations.
+                self._listen_address = self.model.get_binding(self._relation_name).network.bind_address
         return self._listen_address
 
     def set_tls_ca(self, tls_ca):