Support juju expose (#156)

src/charm.py

@@ -8,6 +8,7 @@
 from socket import getfqdn
 from typing import Optional
 
+import ops
 from charms.data_platform_libs.v0.s3 import S3Requirer
 from charms.grafana_k8s.v0.grafana_dashboard import GrafanaDashboardProvider
 from charms.loki_k8s.v0.loki_push_api import LogProxyConsumer
@@ -426,6 +427,18 @@ def _on_leader_elected(self, _: LeaderElectedEvent) -> None:
                     "app", required_password, generate_random_password(PASSWORD_LENGTH)
                 )
 
+    def _open_ports(self) -> None:
+        """Open ports if supported.
+
+        Used if `juju expose` ran on application
+        """
+        if ops.JujuVersion.from_environ().supports_open_port_on_k8s:
+            try:
+                self.unit.open_port("tcp", 3306)
+                self.unit.open_port("tcp", 33060)
+            except ops.ModelError:
+                logger.exception("failed to open port")
+
     def _configure_instance(self, container) -> bool:
         """Configure the instance for use in Group Replication."""
         try:
@@ -466,6 +479,8 @@ def _configure_instance(self, container) -> bool:
             logger.debug("Unable to configure instance: {}".format(e))
             return False
 
+        self._open_ports()
+
         try:
             # Set workload version
             if workload_version := self._mysql.get_mysql_version():