IcingaDB Check: Multiple Responsible Instances

By design, only one Icinga 2 instance should be responsible in the HA
context. If this promise is broken, the Icinga 2 IcingaDB check should
report it.

The code did not check for invalid data in icingadb:telemetry:heartbeat.
With this change, it will go CRITICAL with a descriptive message and
report the actual number of icingadb_responsible_instances in the
performance data.

lib/icingadb/icingadbchecktask.cpp

@@ -227,15 +227,17 @@ void IcingadbCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const CheckR
 		perfdata->Add(new PerfdataValue("icinga2_heartbeat_age", heartbeatLag, false, "seconds", heartbeatLagWarning, Empty, 0));
 	}
 
-	if (weResponsible) {
+	if (weResponsible && otherResponsible) {
+		critmsgs << " Both this instance and another instance are responsible!";
+	} else if (weResponsible) {
 		idbokmsgs << "\n* Responsible";
 	} else if (otherResponsible) {
 		idbokmsgs << "\n* Not responsible, but another instance is";
 	} else {
 		critmsgs << " No instance is responsible!";
 	}
 
-	perfdata->Add(new PerfdataValue("icingadb_responsible_instances", int(weResponsible || otherResponsible), false, "", Empty, Empty, 0, 1));
+	perfdata->Add(new PerfdataValue("icingadb_responsible_instances", int(weResponsible) + int(otherResponsible), false, "", Empty, Empty, 0, 1));
 
 	const auto clockDriftWarning (5);
 	const auto clockDriftCritical (30);