Send a page when the free memory is less than 5% of available memory on

a system

roles/prometheus/templates/alerting.rules.j2

@@ -21,7 +21,7 @@ groups:
     annotations:
       summary: "{% raw %}Endpoint {{ $labels.instance }} is down for more than 10s{% endraw %}"
   - alert: High memory usage
-    expr: (node_memory_MemTotal_bytes - node_memory_MemAvailable_bytes) / node_memory_MemTotal_bytes > 0.8
+    expr: (node_memory_MemTotal_bytes - node_memory_MemAvailable_bytes) / node_memory_MemTotal_bytes > 0.95
     annotations:
       summary: "{% raw %}Instance {{ $labels.instance }} has less than 20% of RAM available{% endraw %}"
   - alert: High disk usage