Add some useful utility methods (#72)

* Add some useful utility methods

* linting

* small refactor

* Update lib/charms/observability_libs/v1/cert_handler.py

Co-authored-by: Mateusz Kulewicz <mateusz.kulewicz@gmail.com>

* Update lib/charms/observability_libs/v1/cert_handler.py

Co-authored-by: Luca Bello <36242061+lucabello@users.noreply.github.com>

---------

Co-authored-by: Mateusz Kulewicz <mateusz.kulewicz@gmail.com>
Co-authored-by: Luca Bello <36242061+lucabello@users.noreply.github.com>

lib/charms/observability_libs/v1/cert_handler.py

@@ -66,7 +66,7 @@
 
 LIBID = "b5cd5cd580f3428fa5f59a8876dcbe6a"
 LIBAPI = 1
-LIBPATCH = 0
+LIBPATCH = 1
 
 
 def is_ip_address(value: str) -> bool:
@@ -297,13 +297,19 @@ def _on_certificate_available(self, event: CertificateAvailableEvent) -> None:
                 relation.data[self.charm.unit]["secret-id"] = secret.id  # pyright: ignore
                 self.on.cert_changed.emit()  # pyright: ignore
 
-    def _retrieve_from_secret(self, value: str, secret_id_name: str) -> Optional[str]:
+    def _retrieve_secret_id(self, secret_id_name: str) -> Optional[str]:
         if not (relation := self.charm.model.get_relation(self.certificates_relation_name)):
             return None
 
         if not (secret_id := relation.data[self.charm.unit].get(secret_id_name)):
             return None
 
+        return secret_id
+
+    def _retrieve_from_secret(self, value: str, secret_id_name: str) -> Optional[str]:
+        if not (secret_id := self._retrieve_secret_id(secret_id_name)):
+            return None
+
         if not (secret := self.model.get_secret(id=secret_id)):
             return None
 
@@ -315,6 +321,11 @@ def private_key(self) -> Optional[str]:
         """Private key."""
         return self._retrieve_from_secret("private-key", "private-key-secret-id")
 
+    @property
+    def private_key_secret_id(self) -> Optional[str]:
+        """ID of the Juju Secret for the Private key."""
+        return self._retrieve_secret_id("private-key-secret-id")
+
     @property
     def _csr(self) -> Optional[str]:
         return self._retrieve_from_secret("csr", "csr-secret-id")
@@ -338,6 +349,11 @@ def ca_cert(self) -> Optional[str]:
         """CA Certificate."""
         return self._retrieve_from_secret("ca-cert", "secret-id")
 
+    @property
+    def ca_server_cert_secret_id(self) -> Optional[str]:
+        """CA server cert secret id."""
+        return self._retrieve_secret_id("secret-id")
+
     @property
     def server_cert(self) -> Optional[str]:
         """Server Certificate."""
@@ -376,13 +392,13 @@ def _on_certificate_invalidated(self, event: CertificateInvalidatedEvent) -> Non
         self._generate_csr(overwrite=True, clear_cert=True)
         self.on.cert_changed.emit()  # pyright: ignore
 
-    def _on_all_certificates_invalidated(self, event: AllCertificatesInvalidatedEvent) -> None:
+    def _on_all_certificates_invalidated(self, _: AllCertificatesInvalidatedEvent) -> None:
         # Do what you want with this information, probably remove all certificates
         # Note: assuming "limit: 1" in metadata
         self._generate_csr(overwrite=True, clear_cert=True)
         self.on.cert_changed.emit()  # pyright: ignore
 
-    def _on_certificates_relation_broken(self, event: RelationBrokenEvent) -> None:
+    def _on_certificates_relation_broken(self, _: RelationBrokenEvent) -> None:
         """Clear the certificates data when removing the relation."""
         try:
             secret = self.model.get_secret(label="csr-secret-id")