Add traefik_route to serve tracing endpoints through ingress if it exists

charmcraft.yaml

@@ -56,8 +56,12 @@ requires:
   logging:
     interface: loki_push_api
   ingress:
-    interface: ingress
+    interface: traefik_route
     limit: 1
+    description: |
+      Ingress integration for Tempo server and Tempo receiver endpoints,
+      so that cross-model workloads can send their traces to Tempo through the ingress.
+      Uses `traefik_route` to open ports on Traefik host for tracing ingesters.
 
 storage:
   data:

lib/charms/tempo_k8s/v2/tracing.py

@@ -104,7 +104,7 @@ 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 = 3
+LIBPATCH = 4
 
 PYDEPS = ["pydantic"]
 
@@ -308,6 +308,9 @@ class TracingProviderAppData(DatabagModel):  # noqa: D101
     external_url: Optional[str] = None
     """Server url. If an ingress is present, it will be the ingress address."""
 
+    internal_scheme: Optional[str] = None
+    """Scheme for internal communication. If it is present, it will be protocol accepted by the provider."""
+
 
 class TracingRequirerAppData(DatabagModel):  # noqa: D101
     """Application databag model for the tracing requirer."""
@@ -495,6 +498,7 @@ def __init__(
         host: str,
         external_url: Optional[str] = None,
         relation_name: str = DEFAULT_RELATION_NAME,
+        internal_scheme: Optional[Literal["http", "https"]] = "http",
     ):
         """Initialize.
 
@@ -525,6 +529,7 @@ def __init__(
         self._host = host
         self._external_url = external_url
         self._relation_name = relation_name
+        self._internal_scheme = internal_scheme
         self.framework.observe(
             self._charm.on[relation_name].relation_joined, self._on_relation_event
         )
@@ -590,10 +595,11 @@ def publish_receivers(self, receivers: Sequence[RawReceiver]):
             try:
                 TracingProviderAppData(
                     host=self._host,
-                    external_url=self._external_url,
+                    external_url=f"http://{self._external_url}" if self._external_url else None,
                     receivers=[
                         Receiver(port=port, protocol=protocol) for protocol, port in receivers
                     ],
+                    internal_scheme=self._internal_scheme,
                 ).dump(relation.data[self._charm.app])
 
             except ModelError as e:
@@ -822,11 +828,13 @@ def _get_endpoint(
         receiver = receivers[0]
         # if there's an external_url argument (v2.5+), use that. Otherwise, we use the tempo local fqdn
         if app_data.external_url:
-            url = app_data.external_url
+            url = f"{app_data.external_url}:{receiver.port}"
         else:
-            # FIXME: if we don't get an external url but only a
-            #  hostname, we don't know what scheme we need to be using. ASSUME HTTP
-            url = f"http://{app_data.host}:{receiver.port}"
+            if app_data.internal_scheme:
+                url = f"{app_data.internal_scheme}://{app_data.host}:{receiver.port}"
+            else:
+                # if we didn't receive a scheme (old provider), we assume HTTP is used
+                url = f"http://{app_data.host}:{receiver.port}"
 
         if receiver.protocol.endswith("grpc"):
             # TCP protocols don't want an http/https scheme prefix