alertmanager silently discards alerts with bad timestamps, no logging even with --log.level=debug

[james00002]

What did you do?
Alertmanager date/time was set a few hours ahead of prometheus. Alertmanager recieves alerts on v1 api and acknowledges them, but then silently discards them with no clear logging even with --log-level=debug

What did you expect to see?
No log messages about discarding incoming alerts with seemingly invalid timestamps, even with --log-level=debug is used

What did you see instead? Under which circumstances?
No indication of why alerts were being discarded, or even that it was happening. The behaviour of ignoring invalid alerts with bad timestamps seems correct, the only concern is the lack of logging.

Environment

• System information:

  Linux 3.10.0-1127.8.2.el7.x86_64 x86_64

• Alertmanager version:

alertmanager, version 0.21.0 (branch: HEAD, revision: 4c6c03ebfe21009c546e4d1e9b92c371d67c021d)
  build user:       root@dee35927357f
  build date:       20200617-08:54:02
  go version:       go1.14.4

• Prometheus version:

prometheus, version 2.20.0 (branch: HEAD, revision: e5a06b483527d4fe0704b8fa3a2b475b661c526f)
  build user:       root@ac954b6d5c6e
  build date:       20200722-18:51:45
  go version:       go1.14.6

• Logs:
  The alertmanager with the date/time in the future suing --log.level=debug logs nothing except for simple "resolved" messages for the alerts it recieves

Jun 04 23:51:45 alertmanager01.g-tr2.oanda.com alertmanager[711]: level=debug ts=2021-06-05T03:51:45.961Z caller=dispatch.go:473 component=dispatcher aggrGroup="{}/{team=\"trading-systems\"}:{alertname=\"InfoHighMemoryUsage\", instance=\"gamenode01-c02-rh.g-tr2.oanda.com:31503\"}" msg=flushing alerts=[InfoHighMemoryUsage[27464a8][resolved]]

[TheMeier]

There has been no activity on this issue for a long time. In the meantime a lot of code has changed in Alertmanager. Therefore I assume that the original request is either not relevant anymore or has been addressed in some other way.

If I am wrong please re-open this issue or open a new one.