Add status, bundle probes

probes/README.md

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+# External probes
+
+These probes are meant to be run from the host where the juju client is installed,
+
+```bash
+juju export-bundle | ./bundle/probe_bundle.py
+juju status --format=yaml | ./status/probe_status.py
+```
+
+or by piping in the bundle yaml,
+
+```bash
+cat bundle.yaml | ./bundle/probe_bundle.py
+cat status.yaml | ./status/probe_status.py
+```

probes/bundle/probe_bundle.py

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+#!/usr/bin/env python3
+
+import sys
+import yaml
+from itertools import combinations
+from collections import defaultdict
+
+
+def one_grafana_agent_per_machine(bundle: dict):
+    applications = bundle["applications"]
+    relations = bundle["relations"]
+
+    # A mapping from app name to the machines it is deployed on
+    principals_to_machines = {k: set(v["to"]) for k, v in applications.items() if "to" in v}
+
+    # List of grafana-agent app names
+    grafana_agent_names = [k for k, v in applications.items() if v["charm"] == "grafana-agent"]
+
+    principals_related_to_grafana_agent = []
+    subordinates_related_to_grafana_agent = []
+    for rel_pair in relations:
+        # Truncate the relation names
+        apps_pair = [s.split(':',-1)[0] for s in rel_pair]
+
+        related_app = None
+        if apps_pair[0] in grafana_agent_names:
+            related_app = apps_pair[1]
+        elif apps_pair[1] in grafana_agent_names:
+            related_app = apps_pair[0]
+
+        if related_app:
+            if related_app in principals_to_machines:
+                principals_related_to_grafana_agent.append(related_app)
+            elif related_app in applications:
+                subordinates_related_to_grafana_agent.append(related_app)
+
+    for app1,app2 in combinations(principals_related_to_grafana_agent, 2):
+        if isect := principals_to_machines[app1].intersection(principals_to_machines[app2]):
+            print(f"grafana-agent is related to '{app1}', '{app2}' on the same machine(s) {isect}")
+
+
+def one_grafana_agent_per_app(bundle: dict):
+    applications = bundle["applications"]
+    relations = bundle["relations"]
+
+    # List of grafana-agent app names
+    grafana_agent_names = [k for k, v in applications.items() if v["charm"] == "grafana-agent"]
+
+    counter = defaultdict(list)
+    for rel_pair in relations:
+        # Truncate the relation names
+        apps_pair = [s.split(':',-1)[0] for s in rel_pair]
+
+        if apps_pair[0] in grafana_agent_names and apps_pair[1] in applications:
+            counter[apps_pair[1]].append(apps_pair[0])
+        elif apps_pair[1] in grafana_agent_names and apps_pair[0] in applications:
+            counter[apps_pair[0]].append(apps_pair[1])
+
+    for k, v in counter.items():
+        if len(v) > 1:
+            print(f"App '{k}' related to multiple grafana-agent apps '{v}'")
+
+if __name__ == '__main__':
+    bundle = yaml.safe_load(sys.stdin.read())
+    one_grafana_agent_per_machine(bundle)
+    one_grafana_agent_per_app(bundle)
+

probes/status/probe_status.py

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+#!/usr/bin/env python3
+
+import sys
+import yaml
+
+
+def one_grafana_agent_per_machine(status: dict):
+    # A mapping from grafana-agent app name to the list of apps it's subordinate to
+    agents = {
+        k: v["subordinate-to"]
+        for k, v in status["applications"].items()
+        if v["charm"] == "grafana-agent"
+    }
+
+    for agent, principals in agents.items():
+        # A mapping from app name to machines
+        machines = {
+            p: [u["machine"] for u in status["applications"][p].get("units", {}).values()]
+            for p in principals
+        }
+
+        from itertools import combinations
+
+        for p1, p2 in combinations(principals, 2):
+            if overlap := set(machines[p1]) & set(machines[p2]):
+                print(
+                    f"{agent} is subordinate to both '{p1}', '{p2}' in the same machines {overlap}"
+                )
+
+
+def one_grafana_agent_per_app(status: dict):
+    # A mapping from grafana-agent app name to the list of apps it's subordinate to
+    agents = {
+        k: v["subordinate-to"]
+        for k, v in status["applications"].items()
+        if v["charm"] == "grafana-agent"
+    }
+
+    for agent, principals in agents.items():
+        for p in principals:
+            for name, unit in status["applications"][p].get("units", {}).items():
+                subord_apps = {u.split("/", -1)[0] for u in unit["subordinates"].keys()}
+                subord_agents = subord_apps & agents.keys()
+                if len(subord_agents) > 1:
+                    print(
+                        f"{name} is related to more than one grafana-agent subordinate: {subord_agents}"
+                    )
+
+
+if __name__ == '__main__':
+    status = yaml.safe_load(sys.stdin.read())
+    one_grafana_agent_per_machine(status)
+    one_grafana_agent_per_app(status)