static check

lib/charms/observability_libs/v1/cert_handler.py

@@ -366,14 +366,14 @@ def __init__(
 
     def _on_refresh_event(self, _):
         # Renew only if there are CSR changes
-        curr_csr = self._csr.encode()
+        curr_csr = self._csr.encode() if self._csr else None
         new_csr = generate_csr(
             private_key=self.private_key.encode(),
             subject=self.cert_subject,
             sans_dns=self.sans_dns,
             sans_ip=self.sans_ip,
         )
-        if curr_csr != new_csr:
+        if curr_csr is not None and curr_csr != new_csr:
             self._generate_csr(renew=True)
 
     def _on_upgrade_charm(self, _):

tests/integration/tester-charm/metadata.yaml

@@ -19,6 +19,12 @@ requires:
       - (client) posting alerts to alertmanager server
       - (server) serving data to grafana
 
+peers:
+  peers:
+    interface: peers
+    description: |
+      peer relation for internal coordination
+
 containers:
   httpbin:
     resource: httpbin-image

tests/integration/tester-charm/src/charm.py

@@ -26,15 +26,38 @@ def __init__(self, *args):
         super().__init__(*args)
         self._name = "httpbin"
         self._container = self.unit.get_container(self._name)
+        sans = ["charm.tester"]
+        if hostname := self._get_hostname_from_peers():
+            sans.append(hostname)
+
+        print("SANSSS ", sans)
         self.cert_handler = CertHandler(
             charm=self,
             key="tester-server-cert",
-            sans=["charm.tester"],
+            sans=sans,
+            refresh_events=[self.on.peers_relation_changed],
         )
         self.framework.observe(self.cert_handler.on.cert_changed, self._on_server_cert_changed)
         self.framework.observe(self.on["httpbin"].pebble_ready, self._on_httpbin_pebble_ready)
         self.framework.observe(self.on.config_changed, self._on_config_changed)
         self.framework.observe(self.on.upgrade_charm, self._on_upgrade_charm)
+        self.framework.observe(self.on.peers_relation_changed, self._on_peers_relation_changed)
+
+    @property
+    def peers(self):
+        """Fetch the peer relation."""
+        return self.model.get_relation("peers")
+
+    def _get_hostname_from_peers(self):
+        if not self.peers:
+            return None
+
+        data = self.peers.data[self.app].get("hostname", None)
+        return data
+
+    def _on_peers_relation_changed(self, _):
+        if self.peers:
+            self.peers.data[self.app]["hostname"] = "custom-hostname"
 
     def _on_upgrade_charm(self, _):
         self._update_cert()