How to: already critical.
inhibit_rules:
- source_matchers:
    - severity="critical"
  target_matchers:
    - severity="warning"
  # Apply inhibition if the alertname is the same.
  # CAUTION: 
  #   If all label names listed in `equal` are missing 
  #   from both the source and target alerts,
  #   the inhibition rule will apply!
  equal: ['alertname']

receivers:
- name: 'team-X-mails'
  email_configs:
  - to: 'team-X+alerts@example.org, team-Y+alerts@example.org'

- name: 'team-X-pager'
  email_configs:
  - to: 'team-X+alerts-critical@example.org'
  pagerduty_configs:
  - routing_key:
- name: 'team-Y-mails'
  email_configs:
  - to: 'team-Y+alerts@example.org'

- name: 'team-Y-pager'
  pagerduty_configs:
  - routing_key:
- name: 'team-DB-pager'
  pagerduty_configs:
  - routing_key:
```