*** WIP. Roll Back. ***

metadata.yaml

@@ -2,7 +2,7 @@
 # Licensed under the GPLv3, see LICENSE file for details.
 name: juju-controller
 assumes:
-- juju >= 3.3
+- juju >= 4.0
 description: |
   The Juju controller charm is used to expose various pieces
   of functionality of a Juju controller.

src/charm.py

@@ -22,19 +22,23 @@
 
 class JujuControllerCharm(CharmBase):
     DB_BIND_ADDR_KEY = 'db-bind-address'
+    ALL_BIND_ADDRS_KEY = 'db-bind-addresses'
+
     _stored = StoredState()
 
     def __init__(self, *args):
         super().__init__(*args)
 
+        self.framework.observe(self.on.install, self._on_install)
         self.framework.observe(self.on.collect_unit_status, self._on_collect_status)
         self.framework.observe(self.on.config_changed, self._on_config_changed)
         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)
 
-        self._stored.set_default(db_bind_address='', last_bind_addresses=[], all_bind_addresses=dict())
+        self._stored.set_default(
+            db_bind_address='', last_bind_addresses=[], all_bind_addresses=dict())
         self.framework.observe(
             self.on.dbcluster_relation_changed, self._on_dbcluster_relation_changed)
 
@@ -45,6 +49,9 @@ def __init__(self, *args):
         self.framework.observe(
             self.on.metrics_endpoint_relation_broken, self._on_metrics_endpoint_relation_broken)
 
+    def _on_collect_status(self, event: InstallEvent):
+
+
     def _on_collect_status(self, event: CollectStatusEvent):
         if len(self._stored.last_bind_addresses) > 1:
             event.add_status(BlockedStatus(
@@ -133,32 +140,47 @@ def _on_metrics_endpoint_relation_broken(self, event: RelationDepartedEvent):
         self.control_socket.remove_metrics_user(username)
 
     def _on_dbcluster_relation_changed(self, event):
-        """Ensure that a bind address for Dqlite is set in relation data,
-        if we can determine a unique one from the relation's bound space.
+        """Maintain our own bind address in relation data.
         If we are the leader, aggregate the bind addresses for all the peers,
         and ensure the result is set in the application data bag.
+        If the aggregate addresses have changed, rewrite the config file.
         """
-        self._ensure_db_bind_address(event)
+        relation = event.relation
+        self._ensure_db_bind_address(relation)
 
         if self.unit.is_leader():
             # The event only has *other* units so include this
             # unit's bind address if we have managed to set it.
             ip = self._stored.db_bind_address
             all_bind_addresses = {self.unit.name: ip} if ip else dict()
 
-            for unit in event.relation.units:
-                unit_data = event.relation.data[unit]
+            for unit in relation.units:
+                unit_data = relation.data[unit]
                 if self.DB_BIND_ADDR_KEY in unit_data:
                     all_bind_addresses[unit.name] = unit_data[self.DB_BIND_ADDR_KEY]
 
             if self._stored.all_bind_addresses == all_bind_addresses:
                 return
 
-            event.relation.data[self.app]['db-bind-addresses'] = json.dumps(all_bind_addresses)
-            self._stored.all_bind_addresses = all_bind_addresses
+            relation.data[self.app][self.ALL_BIND_ADDRS_KEY] = json.dumps(all_bind_addresses)
+            self._update_config_file(all_bind_addresses)
+        else:
+            app_data = relation.data[self.app]
+            if self.ALL_BIND_ADDRS_KEY in app_data:
+                all_bind_addresses = json.loads(app_data[self.ALL_BIND_ADDRS_KEY])
+            else:
+                all_bind_addresses = dict()
+
+            if self._stored.all_bind_addresses == all_bind_addresses:
+                return
+
+            self._update_config_file(all_bind_addresses)
 
-    def _ensure_db_bind_address(self, event):
-        ips = [str(ip) for ip in self.model.get_binding(event.relation).network.ingress_addresses]
+    def _ensure_db_bind_address(self, relation):
+        """Ensure that a bind address for Dqlite is set in relation data,
+        if we can determine a unique one from the relation's bound space.
+        """
+        ips = [str(ip) for ip in self.model.get_binding(relation).network.ingress_addresses]
         self._stored.last_bind_addresses = ips
 
         if len(ips) > 1:
@@ -170,9 +192,24 @@ def _ensure_db_bind_address(self, event):
         if self._stored.db_bind_address == ip:
             return
 
-        event.relation.data[self.unit].update({self.DB_BIND_ADDR_KEY: ip})
+        logger.info('setting new DB bind address: %s', ip)
+        relation.data[self.unit].update({self.DB_BIND_ADDR_KEY: ip})
         self._stored.db_bind_address = ip
 
+    def _update_config_file(self, bind_addresses):
+        # Write this path on install.
+
+        file_path = "something"
+        with open(file_path) as conf_file:
+            conf = yaml.safe_load(conf_file)
+
+        conf['db-bind-addresses'] = bind-addresses
+
+        with open(file_path, 'w') as conf_file:
+            yaml.dump(conf, conf_file)
+
+        self._stored.all_bind_addresses = bind_addresses
+
     def api_port(self) -> str:
         """Return the port on which the controller API server is listening."""
         api_addresses = self._agent_conf('apiaddresses')