feat: support external ca from cloud-integrator (#330)

* feat: support external ca from cloud-integrator

* add comment from pr review

lib/charms/grafana_cloud_integrator/v0/cloud_config_requirer.py

@@ -1,19 +1,21 @@
 """Grafana Cloud Integrator Configuration Requirer."""
+
 import logging
 
 from ops.framework import EventBase, EventSource, Object, ObjectEvents
 
-
 LIBID = "e6f580481c1b4388aa4d2cdf412a47fa"
 LIBAPI = 0
-LIBPATCH = 7
+LIBPATCH = 8
 
 DEFAULT_RELATION_NAME = "grafana-cloud-config"
 
 logger = logging.getLogger(__name__)
 
 
 class Credentials:
+    """Credentials for the remote endpoints."""
+
     def __init__(self, username, password):
         self.username = username
         self.password = password
@@ -25,23 +27,27 @@ class CloudConfigAvailableEvent(EventBase):
     def __init__(self, handle):
         super().__init__(handle)
 
+
 class CloudConfigRevokedEvent(EventBase):
     """Event emitted when cloud config is available."""
 
     def __init__(self, handle):
         super().__init__(handle)
 
+
 class GrafanaCloudConfigEvents(ObjectEvents):
     """Event descriptor for events raised by `GrafanaCloudConfigRequirer`."""
 
     cloud_config_available = EventSource(CloudConfigAvailableEvent)
     cloud_config_revoked = EventSource(CloudConfigRevokedEvent)
 
+
 class GrafanaCloudConfigRequirer(Object):
+    """Requirer side of the Grafana Cloud Config relation."""
 
     on = GrafanaCloudConfigEvents()  # pyright: ignore
 
-    def __init__(self, charm, relation_name = DEFAULT_RELATION_NAME):
+    def __init__(self, charm, relation_name=DEFAULT_RELATION_NAME):
         super().__init__(charm, relation_name)
         self._charm = charm
         self._relation_name = relation_name
@@ -63,18 +69,15 @@ def _is_not_empty(self, s):
 
     @property
     def _change_events(self):
-       return [
+        return [
             self._events.relation_joined,
             self._events.relation_changed,
             self._events.relation_created,
         ]
 
     @property
     def _broken_events(self):
-        return [
-            self._events.relation_departed,
-            self._events.relation_broken
-        ]
+        return [self._events.relation_departed, self._events.relation_broken]
 
     @property
     def _events(self):
@@ -83,12 +86,15 @@ def _events(self):
     @property
     def credentials(self):
         """Return the credentials, if any; otherwise, return None."""
-        if (username := self._data.get("username", "").strip()) and (password := self._data.get("password", "").strip()):
+        if (username := self._data.get("username", "").strip()) and (
+            password := self._data.get("password", "").strip()
+        ):
             return Credentials(username, password)
         return None
 
     @property
     def loki_ready(self):
+        """Check whether there is a non-empty Loki url in relation data."""
         return self._is_not_empty(self.loki_url)
 
     @property
@@ -100,17 +106,27 @@ def loki_endpoint(self) -> dict:
         endpoint = {}
         endpoint["url"] = self.loki_url
         if self.credentials:
-            endpoint["basic_auth"] = {"username": self.credentials.username, "password": self.credentials.password}
+            endpoint["basic_auth"] = {
+                "username": self.credentials.username,
+                "password": self.credentials.password,
+            }
         return endpoint
 
     @property
     def prometheus_ready(self):
+        """Check whether there is a non-empty Prometheus url in relation data."""
         return self._is_not_empty(self.prometheus_url)
 
     @property
     def tempo_ready(self):
+        """Check whether there is a non-empty Tempo url in relation data."""
         return self._is_not_empty(self.tempo_url)
 
+    @property
+    def tls_ca_ready(self):
+        """Check whether there is a TLS CA in relation data."""
+        return self._is_not_empty(self.tls_ca)
+
     @property
     def prometheus_endpoint(self) -> dict:
         """Return the prometheus endpoint dict."""
@@ -120,21 +136,32 @@ def prometheus_endpoint(self) -> dict:
         endpoint = {}
         endpoint["url"] = self.prometheus_url
         if self.credentials:
-            endpoint["basic_auth"] = {"username": self.credentials.username, "password": self.credentials.password}
+            endpoint["basic_auth"] = {
+                "username": self.credentials.username,
+                "password": self.credentials.password,
+            }
         return endpoint
 
     @property
     def loki_url(self) -> str:
+        """The Loki endpoint from relation data."""
         return self._data.get("loki_url", "")
 
     @property
     def tempo_url(self) -> str:
+        """The Tempo endpoint from relation data."""
         return self._data.get("tempo_url", "")
 
     @property
     def prometheus_url(self) -> str:
+        """The Prometheus endpoint from relation data."""
         return self._data.get("prometheus_url", "")
 
+    @property
+    def tls_ca(self) -> str:
+        """TLS CA from relation data."""
+        return self._data.get("tls-ca", "")
+
     @property
     def _data(self):
         for relation in self._charm.model.relations[self._relation_name]:

src/grafana_agent.py

@@ -92,6 +92,8 @@ class GrafanaAgentCharm(CharmBase):
     _key_path = "/tmp/agent/grafana-agent.key"
     _ca_path = "/usr/local/share/ca-certificates/grafana-agent-operator.crt"
     _ca_folder_path = "/usr/local/share/ca-certificates"
+    # We have a `limit: 1` on the cloud integrator relation so we expect only one such cert.
+    _cloud_ca_path = "/usr/local/share/ca-certificates/cloud-integrator.crt"
 
     # mapping from tempo-supported receivers to the receiver ports to be opened on the grafana-agent host
     _tracing_receivers_ports: Dict[ReceiverProtocol, int] = {
@@ -349,6 +351,12 @@ def _on_config_changed(self, _event=None):
 
     def _on_cloud_config_available(self, _) -> None:
         logger.info("cloud config available")
+        # Write CA from cloud config
+        if self._cloud.tls_ca_ready:
+            self.write_file(self._cloud_ca_path, self._cloud.tls_ca)
+        else:
+            self._delete_file_if_exists(self._cloud_ca_path)
+        self.run(["update-ca-certificates", "--fresh"])
         self._update_config()
         self._update_tracing_provider()
 
@@ -1034,7 +1042,7 @@ def _loki_config(self) -> Dict[str, Union[Any, List[Any]]]:
             a dict with Loki config
         """
         configs = []
-        if self._loki_consumer.loki_endpoints:
+        if self._loki_consumer.loki_endpoints or self._cloud.loki_ready:
             configs.append(
                 {
                     "name": "push_api_server",