name : describe-alarm-history.rst **To retrieve history for an alarm** The following example uses the ``describe-alarm-history`` command to retrieve history for the Amazon CloudWatch alarm named "myalarm":: aws cloudwatch describe-alarm-history --alarm-name "myalarm" --history-item-type StateUpdate Output:: { "AlarmHistoryItems": [ { "Timestamp": "2014-04-09T18:59:06.442Z", "HistoryItemType": "StateUpdate", "AlarmName": "myalarm", "HistoryData": "{\"version\":\"1.0\",\"oldState\":{\"stateValue\":\"ALARM\",\"stateReason\":\"testing purposes\"},\"newState\":{\"stateValue\":\"OK\",\"stateReason\":\"Threshold Crossed: 2 datapoints were not greater than the threshold (70.0). The most recent datapoints: [38.958, 40.292].\",\"stateReasonData\":{\"version\":\"1.0\",\"queryDate\":\"2014-04-09T18:59:06.419+0000\",\"startDate\":\"2014-04-09T18:44:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[38.958,40.292],\"threshold\":70.0}}}", "HistorySummary": "Alarm updated from ALARM to OK" }, { "Timestamp": "2014-04-09T18:59:05.805Z", "HistoryItemType": "StateUpdate", "AlarmName": "myalarm", "HistoryData": "{\"version\":\"1.0\",\"oldState\":{\"stateValue\":\"OK\",\"stateReason\":\"Threshold Crossed: 2 datapoints were not greater than the threshold (70.0). The most recent datapoints: [38.839999999999996, 39.714].\",\"stateReasonData\":{\"version\":\"1.0\",\"queryDate\":\"2014-03-11T22:45:41.569+0000\",\"startDate\":\"2014-03-11T22:30:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[38.839999999999996,39.714],\"threshold\":70.0}},\"newState\":{\"stateValue\":\"ALARM\",\"stateReason\":\"testing purposes\"}}", "HistorySummary": "Alarm updated from OK to ALARM" } ] }