TLS part 1: Enable TLS if cert is available

.gitignore

@@ -9,3 +9,4 @@ build/
 .idea/
 .tox/
 .mypy_cache
+**/*.egg-info/

charmcraft.yaml

@@ -11,5 +11,6 @@ bases:
       channel: "20.04"
 parts:
   charm:
+    charm-binary-python-packages: [cryptography, jsonschema]
     build-packages:
     - git

lib/charms/alertmanager_k8s/v0/alertmanager_dispatch.py

@@ -42,7 +42,7 @@ def __init__(self, *args):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 7
+LIBPATCH = 8
 
 # Set to match metadata.yaml
 INTERFACE_NAME = "alertmanager_dispatch"
@@ -172,6 +172,7 @@ def _on_relation_changed(self, event: ops.charm.RelationChangedEvent):
 
     def get_cluster_info(self) -> List[str]:
         """Returns a list of ip addresses of all the alertmanager units."""
+        # FIXME need to tell prometheus that `scheme: https`.
         alertmanagers = []  # type: List[str]
         relation = self.charm.model.get_relation(self.name)
         if not relation: