
= Alarm History

Use the Alarm History API to retrieve state changes and point-in-time snapshots for alarms.

NOTE: This endpoint is only available when the Alarm History feature is enabled.
See <<operation:deep-dive/alarms/history.adoc#ga-alarm-history, Alarm History>> for details.

== GETs (reading data)

[caption=]
.Alarm History API GET functions
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|===
| Resource  | Description

| /alarms/history/\{alarmid}/states
| Retrieve the complete set of state changes for the given alarm.

| /alarms/history/\{alarmid}
| Retrieve the last known state of an alarm at the given time.

| /alarms/history
| Retrieve the last known state of all alarms which were active at the given time.
|===

[caption=]
.Alarm History API GET functions
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|===
| Name  | Default Value | Comment

| matchType
| alarm-id
| By default we look up alarms based on the given database ID.
Use this property to change the matching behavior to look up by reduction key instead.

| at
| _Current time_
| Timestamp, in milliseconds.
|===
