rules.yml

groups:
    - name: AllInstances
     rules:
     - alert: InstanceDown
       # Condition for alerting
       expr: up == 0
       for: 1m
       # Annotation - additional informational labels to store more information
       annotations:
         title: 'Instance {{ $labels.instance }} down'
         description: '{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 1 minute.'
       # Labels - additional labels to be attached to the alert
       labels:
           severity: 'critical'