Fix juju_unit and juju_application labels

lib/charms/nrpe_exporter/v0/nrpe_exporter.py

@@ -50,7 +50,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 5
+LIBPATCH = 6
 
 
 logger = logging.getLogger(__name__)
@@ -441,10 +441,14 @@ def _generate_data(self, relation) -> Tuple[list, list]:
                     )
                     id = re.sub(r"^juju[-_]", "", id)
 
+                    nagios_host_context = relation.data[unit].get("nagios_host_context", "")
+
                     alerts.append(self._generate_alert(relation, cmd, id, unit))
 
                     nrpe_endpoints.append(
-                        self._generate_prometheus_job(relation, unit, cmd, exporter_address, id)
+                        self._generate_prometheus_job(
+                            relation, unit, cmd, exporter_address, id, nagios_host_context
+                        )
                     )
             else:
                 logger.debug("No NRPE check is defined.")
@@ -485,13 +489,19 @@ def _generate_alert(self, relation, cmd, id, unit) -> dict:
             },
         }
 
-    def _generate_prometheus_job(self, relation, unit, cmd, exporter_address, id) -> dict:
+    def _generate_prometheus_job(
+        self, relation, unit, cmd, exporter_address, id, nagios_host_context
+    ) -> dict:
         """Generate an on-the-fly Prometheus scrape job."""
         # IP address could be 'target-address' OR 'target_address'
         addr = relation.data[unit].get("target-address", "") or relation.data[unit].get(
             "target_address", ""
         )
 
+        # "nagios_host_content" is needed to extract it from the "id" parameter (target-id)
+        # so that we can correctly relabel juju_application and juju_unit.
+        nagios_host_context = nagios_host_context + "-" if nagios_host_context else ""
+
         return {
             "app_name": relation.app.name,
             "target": {
@@ -511,8 +521,21 @@ def _generate_prometheus_job(self, relation, unit, cmd, exporter_address, id) ->
                     },
                     {
                         "target_label": "juju_unit",
-                        # Turn sql-foo-0 or redis_bar_1 into sql-foo/0 or redis-bar/1
-                        "replacement": re.sub(r"^(.*?)[-_](\d+)$", r"\1/\2", id.replace("_", "-")),
+                        # Turn nagios-host-context-sql-foo-0 into sql-foo/0
+                        "replacement": re.sub(
+                            r"^(.*?)[-_](\d+)$",
+                            r"\1/\2",
+                            id.replace("_", "-").replace(nagios_host_context, ""),
+                        ),
+                    },
+                    {
+                        "target_label": "juju_application",
+                        # Turn nagios-host-context-sql-foo-0 into sql-foo
+                        "replacement": re.sub(
+                            r"^(.*?)[-_](\d+)$",
+                            r"\1",
+                            id.replace("_", "-").replace(nagios_host_context, ""),
+                        ),
                     },
                 ],
                 "updates": {

lib/charms/prometheus_k8s/v0/prometheus_scrape.py

@@ -178,7 +178,7 @@ def __init__(self, *args):
 - `scrape_timeout`
 - `proxy_url`
 - `relabel_configs`
-- `metrics_relabel_configs`
+- `metric_relabel_configs`
 - `sample_limit`
 - `label_limit`
 - `label_name_length_limit`
@@ -362,7 +362,7 @@ def _on_scrape_targets_changed(self, event):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 44
+LIBPATCH = 47
 
 PYDEPS = ["cosl"]
 
@@ -377,7 +377,7 @@ def _on_scrape_targets_changed(self, event):
     "scrape_timeout",
     "proxy_url",
     "relabel_configs",
-    "metrics_relabel_configs",
+    "metric_relabel_configs",
     "sample_limit",
     "label_limit",
     "label_name_length_limit",
@@ -521,8 +521,8 @@ def expand_wildcard_targets_into_individual_jobs(
                         # for such a target. Therefore labeling with Juju topology, excluding the
                         # unit name.
                         non_wildcard_static_config["labels"] = {
-                            **non_wildcard_static_config.get("labels", {}),
                             **topology.label_matcher_dict,
+                            **non_wildcard_static_config.get("labels", {}),
                         }
 
                     non_wildcard_static_configs.append(non_wildcard_static_config)
@@ -547,9 +547,9 @@ def expand_wildcard_targets_into_individual_jobs(
                         if topology:
                             # Add topology labels
                             modified_static_config["labels"] = {
-                                **modified_static_config.get("labels", {}),
                                 **topology.label_matcher_dict,
                                 **{"juju_unit": unit_name},
+                                **modified_static_config.get("labels", {}),
                             }
 
                             # Instance relabeling for topology should be last in order.
@@ -1537,12 +1537,11 @@ def set_scrape_job_spec(self, _=None):
             relation.data[self._charm.app]["scrape_metadata"] = json.dumps(self._scrape_metadata)
             relation.data[self._charm.app]["scrape_jobs"] = json.dumps(self._scrape_jobs)
 
-            if alert_rules_as_dict:
-                # Update relation data with the string representation of the rule file.
-                # Juju topology is already included in the "scrape_metadata" field above.
-                # The consumer side of the relation uses this information to name the rules file
-                # that is written to the filesystem.
-                relation.data[self._charm.app]["alert_rules"] = json.dumps(alert_rules_as_dict)
+            # Update relation data with the string representation of the rule file.
+            # Juju topology is already included in the "scrape_metadata" field above.
+            # The consumer side of the relation uses this information to name the rules file
+            # that is written to the filesystem.
+            relation.data[self._charm.app]["alert_rules"] = json.dumps(alert_rules_as_dict)
 
     def _set_unit_ip(self, _=None):
         """Set unit host address.

pyproject.toml

@@ -43,3 +43,7 @@ pythonPlatfrom = "All"
 [tool.pytest.ini_options]
 minversion = "6.0"
 log_cli_level = "INFO"
+
+[tool.codespell]
+skip = ".git,.tox,build,lib,venv*,.mypy_cache"
+ignore-words-list = "assertIn"

src/charm.py

@@ -130,7 +130,7 @@ def __init__(self, *args):
         self.metrics_aggregator = MetricsEndpointAggregator(self, resolve_addresses=True)
         self.cos_agent = COSAgentProvider(
             self,
-            scrape_configs=self._get_scrape_configs,
+            scrape_configs=self._get_scrape_configs(),
             metrics_rules_dir=RULES_DIR,
             dashboard_dirs=[COS_PROXY_DASHBOARDS_DIR, DASHBOARDS_DIR],
             refresh_events=[

tests/unit/test_relation_monitors.py

@@ -1,3 +1,4 @@
+import json
 import tempfile
 import unittest
 from pathlib import Path
@@ -24,6 +25,7 @@ def setUp(self):
             "private-address": "10.41.168.226",
             "target-address": "10.41.168.226",
             "target-id": "ubuntu-0",
+            "nagios_host_context": "my-nagios-host-context",
         }
 
         for p in [
@@ -97,10 +99,21 @@ def test_prometheus(self):
 
         # THEN alert rules are transferred to prometheus over relation data
         app_data = self.harness.get_relation_data(rel_id_prom, "cos-proxy")
-        self.assertIn("alert_rules", app_data)
+
+        self.assertIn("alert_rules", app_data)  # pyright: ignore
 
         # AND status is "active"
         self.assertIsInstance(
             self.harness.model.unit.status,
             ActiveStatus,
         )
+        # AND relabel configs are ok (we are removing nagios_host_context)
+        scrape_jobs = json.loads(app_data["scrape_jobs"])
+        for job in scrape_jobs:
+            relabel_configs = job["relabel_configs"]
+            for config in relabel_configs:
+                if target_level := config.get("target_label"):
+                    if target_level == "juju_application":
+                        self.assertEquals(config["replacement"], "ubuntu")
+                    elif target_level == "juju_unit":
+                        self.assertEquals(config["replacement"], "ubuntu/0")

tox.ini

@@ -44,7 +44,7 @@ deps =
     codespell<2.3.0 # https://github.com/codespell-project/codespell/issues/3430
 commands =
     codespell {[vars]lib_path}
-    codespell . --skip .git --skip .tox --skip build --skip lib --skip venv* --skip .mypy_cache
+    codespell .
     ruff {[vars]all_path}
     black --check --diff {[vars]all_path}