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Timing checks

repeat-before-group

Level: warn

repeat_interval is shorter than group_interval. This means Alertmanager will send repeat notifications before the grouped batch has had a chance to fire again — generating more noise than expected.

route:
  receiver: default
  group_interval: 1h
  repeat_interval: 5m     # repeats every 5m, but group fires every 1h

route:
  receiver: default
  group_interval: 5m
  repeat_interval: 4h     # repeat_interval should be >= group_interval

Typical values:

field recommended
group_wait 30s – 2m
group_interval 5m – 15m
repeat_interval 1h – 24h

wait-exceeds-interval

Level: warn

group_wait is longer than group_interval. This means subsequent alerts in the group will be sent before the initial group_wait has expired.

route:
  receiver: default
  group_wait: 10m      # wait 10 minutes before first notification
  group_interval: 2m   # but send updates every 2 minutes

route:
  receiver: default
  group_wait: 30s
  group_interval: 5m   # group_interval should be > group_wait

undefined-time-interval

Level: error

A route references a time interval name in mute_time_intervals or active_time_intervals that is not defined in time_intervals. Alertmanager will reject this config at runtime.

route:
  receiver: default
  mute_time_intervals: [maintenance]   # not defined below!

receivers:
  - name: default
    slack_configs: [...]

route:
  receiver: default
  mute_time_intervals: [maintenance]

receivers:
  - name: default
    slack_configs: [...]

time_intervals:
  - name: maintenance
    time_intervals:
      - weekdays: [saturday, sunday]
        times:
          - start_time: '00:00'
            end_time: '24:00'

global-resolve-timeout-missing

Level: info

global.resolve_timeout is not set. Alertmanager uses a default of 5m — after 5 minutes without a firing alert, it marks the alert resolved and sends a resolve notification.

This may be too short (spurious resolves for flapping alerts) or too long (delayed recovery notices). Setting it explicitly makes the intent clear and reviewable in code.

route:
  receiver: default
# no global: section — resolve_timeout silently defaults to 5m

global:
  resolve_timeout: 5m   # explicit: 5m, 15m, 1h — whatever fits your alerts

route:
  receiver: default