Filter out unlabelled metrics from ContainerMemoryUsage alert

flux2/config/monitoring/stackspin-alerts-prometheusrule.yaml

@@ -68,7 +68,7 @@ spec:
 
       # https://awesome-prometheus-alerts.grep.to/rules#rule-docker-containers-1-4
       - alert: ContainerMemoryUsage
-        expr: (sum(container_memory_working_set_bytes) BY (container) / sum(container_spec_memory_limit_bytes > 0) BY (container) * 100) > 80
+        expr: (sum(container_memory_working_set_bytes{container!=""}) BY (pod,container) / sum(container_spec_memory_limit_bytes{container!=""} > 0) BY (pod,container) * 100) > 80
         for: 2m
         labels:
           severity: warning