Update coordinator to support multiple config generations

charmcraft.yaml

@@ -133,8 +133,8 @@ bases:
 parts:
   charm:
     # uncomment this if you add git+ dependencies in requirements.txt:
-    # build-packages:
-    # - "git"
+    build-packages:
+    - "git"
     charm-binary-python-packages:
       - "pydantic>=2"
       - "cryptography"

requirements.txt

@@ -5,7 +5,8 @@ lightkube>=0.15.4
 lightkube-models>=1.24.1.4
 tenacity==8.2.3
 pydantic>=2
-cosl>=0.0.48
+# TODO: update when cosl is merged
+cosl@git+https://github.com/canonical/cos-lib@publish-version
 
 # crossplane is a package from nginxinc to interact with the Nginx config
 crossplane

src/charm.py

@@ -3,6 +3,7 @@
 # See LICENSE file for licensing details.
 
 """Charmed Operator for Tempo; a lightweight object storage based tracing backend."""
+
 import json
 import logging
 import re
@@ -33,7 +34,7 @@
 from ops.charm import CharmBase
 
 from nginx_config import NginxConfig
-from tempo import Tempo
+from tempo import Tempo, TempoConfigBuilderFactory
 from tempo_config import TEMPO_ROLES_CONFIG
 
 logger = logging.getLogger(__name__)
@@ -73,7 +74,13 @@ class PeerData(DatabagModel):
 @trace_charm(
     tracing_endpoint="tempo_otlp_http_endpoint",
     server_cert="server_ca_cert",
-    extra_types=(Tempo, TracingEndpointProvider, Coordinator, ClusterRolesConfig),
+    extra_types=(
+        Tempo,
+        TracingEndpointProvider,
+        Coordinator,
+        ClusterRolesConfig,
+        TempoConfigBuilderFactory,
+    ),
     # use PVC path for buffer data, so we don't lose it on pod churn
     buffer_path=Path("/tempo-data/.charm_tracing_buffer.raw"),
 )
@@ -88,6 +95,7 @@ def __init__(self, *args):
             requested_receivers=self._requested_receivers,
             retention_period_hours=self._trace_retention_period_hours,
         )
+        self.tempo_config_factory = TempoConfigBuilderFactory(tempo=self.tempo)
         # set alert_rules_path="", as we don't want to populate alert rules into the relation databag
         # we only need `self._remote_write.endpoints`
         self._remote_write = PrometheusRemoteWriteConsumer(self, alert_rules_path="")
@@ -117,12 +125,12 @@ def __init__(self, *args):
                 "catalogue": "catalogue",
             },
             nginx_config=NginxConfig(server_name=self.hostname).config,
-            workers_config=self.tempo.config,
+            workers_config=self.tempo_config_factory.config,
             resources_requests=self.get_resources_requests,
             container_name="charm",
             remote_write_endpoints=self.remote_write_endpoints,  # type: ignore
-            # TODO: future Tempo releases would be using otlp_xx protocols instead.
-            workload_tracing_protocols=["jaeger_thrift_http"],
+            # keep jaeger_thrift_http for backward compatibility
+            workload_tracing_protocols=["otlp_http", "jaeger_thrift_http"],
             catalogue_item=self._catalogue_item,
         )
 
@@ -142,7 +150,8 @@ def __init__(self, *args):
 
         # peer
         self.framework.observe(
-            self.on[PEERS_RELATION_ENDPOINT_NAME].relation_created, self._on_peers_relation_created
+            self.on[PEERS_RELATION_ENDPOINT_NAME].relation_created,
+            self._on_peers_relation_created,
         )
 
         # refuse to handle any other event as we can't possibly know what to do.
@@ -226,7 +235,7 @@ def enabled_receivers(self) -> Set[str]:
         enabled_receivers = set()
         # otlp_http is needed by charm_tracing
         enabled_receivers.add("otlp_http")
-        # jaeger_thrift_http is needed by Tempo's internal workload traces
+        # backward compatibility for workload traces
         enabled_receivers.add("jaeger_thrift_http")
         enabled_receivers.update(
             [