update charm-relation-interfaces to use prometheus_scrape schema that…

… is compatible with pydantic v2 (#141)

This:
* rebuilds the charm, pulling a new version of the charm-relation-interfaces that is compatible with pydantic v2
* rewrites the `test_scrape_jobs_are_forwarded_on_adding_prometheus_then_targets` test in scenario in order to replicate [this issue](#140).  The previous unit test conceptually should have caught this bug, but because the issue occurred when calling `._get_scrape_configs()`, which is only called in __init__, unit tests did not reproduce this bug because Harness reuses the Charm object (eg: __init__ is only called once during `harness.begin()`, not on every event like in real Juju).  By refactoring to scenario, we more closely reproduce true Juju behavior and capture the bug.

tests/scenario/helpers.py

@@ -0,0 +1,12 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+from pathlib import Path
+
+import yaml
+
+CHARM_ROOT = Path(__file__).parent.parent.parent
+
+
+def get_charm_meta() -> dict:
+    raw_meta = (CHARM_ROOT / "metadata").with_suffix(".yaml").read_text()
+    return yaml.safe_load(raw_meta)

tests/scenario/test_charm.py

@@ -0,0 +1,77 @@
+import json
+
+import scenario
+from charm import COSProxyCharm
+
+from tests.scenario.helpers import get_charm_meta
+
+RELABEL_INSTANCE_CONFIG = {
+    "source_labels": [
+        "juju_model",
+        "juju_model_uuid",
+        "juju_application",
+        "juju_unit",
+    ],
+    "separator": "_",
+    "target_label": "instance",
+    "regex": "(.*)",
+}
+
+
+def test_scrape_jobs_are_forwarded_on_adding_prometheus_then_targets():
+    # Arrange
+    prometheus_scrape_relation = scenario.Relation(
+        "downstream-prometheus-scrape",
+        remote_app_name="cos-prometheus",
+        remote_units_data={
+            0: {},
+        },
+    )
+    prometheus_target_relation = scenario.Relation(
+        "prometheus-target",
+        remote_app_name="target-app",
+        remote_units_data={
+            0: {
+                "hostname": "scrape_target_0",
+                "port": "1234",
+            },
+        },
+    )
+
+    model_name = "testmodel"
+    model_uuid = "ae3c0b14-9c3a-4262-b560-7a6ad7d3642f"
+    model = scenario.Model(model_name, model_uuid)
+
+    ctx = scenario.Context(COSProxyCharm, meta=get_charm_meta())
+    state_in = scenario.State(
+        leader=True,
+        relations=[prometheus_scrape_relation, prometheus_target_relation],
+        model=model,
+    )
+
+    expected_jobs = [
+        {
+            "job_name": f"juju_{model_name}_{model_uuid[:7]}_target-app_prometheus_scrape",
+            "static_configs": [
+                {
+                    "targets": ["scrape_target_0:1234"],
+                    "labels": {
+                        "juju_model": model_name,
+                        "juju_model_uuid": model_uuid,
+                        "juju_application": "target-app",
+                        "juju_unit": "target-app/0",
+                        "host": "scrape_target_0",
+                        "dns_name": "scrape_target_0",
+                    },
+                }
+            ],
+            "relabel_configs": [RELABEL_INSTANCE_CONFIG],
+        }
+    ]
+
+    # Act
+    out = ctx.run(prometheus_target_relation.changed_event, state_in)
+
+    # Assert
+    actual_jobs = json.loads(out.relations[0].local_app_data.get("scrape_jobs", []))
+    assert actual_jobs == expected_jobs

tests/unit/test_charm.py

@@ -201,50 +201,6 @@ def test_dashboards_without_grafana_relations_blocks(self):
             BlockedStatus("Missing one of (Grafana|dashboard|grafana-agent) relation(s)"),
         )
 
-    def test_scrape_jobs_are_forwarded_on_adding_prometheus_then_targets(self):
-        self.harness.set_leader(True)
-
-        prometheus_rel_id = self.harness.add_relation(
-            "downstream-prometheus-scrape", "cos-prometheus"
-        )
-        self.harness.add_relation_unit(prometheus_rel_id, "cos-prometheus/0")
-
-        target_rel_id = self.harness.add_relation("prometheus-target", "target-app")
-        self.harness.add_relation_unit(target_rel_id, "target-app/0")
-        self.harness.update_relation_data(
-            target_rel_id,
-            "target-app/0",
-            {
-                "hostname": "scrape_target_0",
-                "port": "1234",
-            },
-        )
-
-        prometheus_rel_data = self.harness.get_relation_data(
-            prometheus_rel_id, self.harness.model.app.name
-        )
-        scrape_jobs = json.loads(prometheus_rel_data.get("scrape_jobs", "[]"))
-        expected_jobs = [
-            {
-                "job_name": "juju_testmodel_ae3c0b1_target-app_prometheus_scrape",
-                "static_configs": [
-                    {
-                        "targets": ["scrape_target_0:1234"],
-                        "labels": {
-                            "juju_model": "testmodel",
-                            "juju_model_uuid": "ae3c0b14-9c3a-4262-b560-7a6ad7d3642f",
-                            "juju_application": "target-app",
-                            "juju_unit": "target-app/0",
-                            "host": "scrape_target_0",
-                            "dns_name": "scrape_target_0",
-                        },
-                    }
-                ],
-                "relabel_configs": [RELABEL_INSTANCE_CONFIG],
-            }
-        ]
-        self.assertListEqual(scrape_jobs, expected_jobs)
-
     def test_scrape_jobs_are_forwarded_on_adding_targets_then_prometheus(self):
         self.harness.set_leader(True)