Add extra useful methods and one bugfix (#51)

* add method to determine if TLS is enabled

* fix bug with cer relation name. add len(units) hack. ca_method

* fix linting

lib/charms/observability_libs/v0/cert_handler.py

@@ -62,7 +62,7 @@
 
 LIBID = "b5cd5cd580f3428fa5f59a8876dcbe6a"
 LIBAPI = 0
-LIBPATCH = 1
+LIBPATCH = 2
 
 
 class CertChanged(EventBase):
@@ -139,7 +139,7 @@ def __init__(
  self._on_all_certificates_invalidated,
  )
  self.framework.observe(
- self.charm.on.certificates_relation_broken, # pyright: ignore
+ self.charm.on[self.certificates_relation_name].relation_broken, # pyright: ignore
  self._on_certificates_relation_broken,
  )
 
@@ -148,6 +148,16 @@ def __init__(
  self.charm.on[self.peer_relation_name].relation_created, self._on_peer_relation_created
  )
 
+ @property
+ def enabled(self) -> bool:
+ """Boolean indicating whether the charm has a tls_certificates relation."""
+ # We need to check for units as a temporary workaround because of https://bugs.launchpad.net/juju/+bug/2024583
+ # This could in theory not work correctly on scale down to 0 but it is necessary for the moment.
+ return (
+ len(self.charm.model.relations[self.certificates_relation_name]) > 0
+ and len(self.charm.model.get_relation(self.certificates_relation_name).units) > 0 # type: ignore
+ )
+
  @property
  def _peer_relation(self) -> Optional[Relation]:
  """Return the peer relation."""
@@ -302,6 +312,11 @@ def cert(self):
  """Return the server cert."""
  return self._server_cert
 
+ @property
+ def ca(self):
+ """Return the CA cert."""
+ return self._ca_cert
+
  @property
  def _server_cert(self) -> Optional[str]:
  if self._peer_relation: