Alarm events and EventBridge
CloudWatch sends events to Amazon EventBridge whenever a CloudWatch alarm is created, updated, deleted, or changes alarm state. You can use EventBridge and these events to write rules that take actions, such as notifying you, when an alarm changes state. For more information, see What is Amazon EventBridge?
CloudWatch guarantees the delivery of alarm state change events to EventBridge.
Sample events from CloudWatch
This section includes example events from CloudWatch.
State change for a single-metric alarm
{ "version": "0", "id": "c4c1c1c9-6542-e61b-6ef0-8c4d36933a92", "detail-type": "CloudWatch Alarm State Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2019-10-02T17:04:40Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServerCpuTooHigh" ], "detail": { "alarmName": "ServerCpuTooHigh", "configuration": { "description": "Goes into alarm when server CPU utilization is too high!", "metrics": [ { "id": "30b6c6b2-a864-43a2-4877-c09a1afc3b87", "metricStat": { "metric": { "dimensions": { "InstanceId": "i-12345678901234567" }, "name": "CPUUtilization", "namespace": "AWS/EC2" }, "period": 300, "stat": "Average" }, "returnData": true } ] }, "previousState": { "reason": "Threshold Crossed: 1 out of the last 1 datapoints [0.0666851903306472 (01/10/19 13:46:00)] was not greater than the threshold (50.0) (minimum 1 datapoint for ALARM -> OK transition).", "reasonData": "{\"version\":\"1.0\",\"queryDate\":\"2019-10-01T13:56:40.985+0000\",\"startDate\":\"2019-10-01T13:46:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[0.0666851903306472],\"threshold\":50.0}", "timestamp": "2019-10-01T13:56:40.987+0000", "value": "OK" }, "state": { "reason": "Threshold Crossed: 1 out of the last 1 datapoints [99.50160229693434 (02/10/19 16:59:00)] was greater than the threshold (50.0) (minimum 1 datapoint for OK -> ALARM transition).", "reasonData": "{\"version\":\"1.0\",\"queryDate\":\"2019-10-02T17:04:40.985+0000\",\"startDate\":\"2019-10-02T16:59:00.000+0000\",\"statistic\":\"Average\",\"period\":300,\"recentDatapoints\":[99.50160229693434],\"threshold\":50.0}", "timestamp": "2019-10-02T17:04:40.989+0000", "value": "ALARM" } } }
State change for a metric math alarm
{ "version": "0", "id": "2dde0eb1-528b-d2d5-9ca6-6d590caf2329", "detail-type": "CloudWatch Alarm State Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2019-10-02T17:20:48Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:TotalNetworkTrafficTooHigh" ], "detail": { "alarmName": "TotalNetworkTrafficTooHigh", "configuration": { "description": "Goes into alarm if total network traffic exceeds 10Kb", "metrics": [ { "expression": "SUM(METRICS())", "id": "e1", "label": "Total Network Traffic", "returnData": true }, { "id": "m1", "metricStat": { "metric": { "dimensions": { "InstanceId": "i-12345678901234567" }, "name": "NetworkIn", "namespace": "AWS/EC2" }, "period": 300, "stat": "Maximum" }, "returnData": false }, { "id": "m2", "metricStat": { "metric": { "dimensions": { "InstanceId": "i-12345678901234567" }, "name": "NetworkOut", "namespace": "AWS/EC2" }, "period": 300, "stat": "Maximum" }, "returnData": false } ] }, "previousState": { "reason": "Unchecked: Initial alarm creation", "timestamp": "2019-10-02T17:20:03.642+0000", "value": "INSUFFICIENT_DATA" }, "state": { "reason": "Threshold Crossed: 1 out of the last 1 datapoints [45628.0 (02/10/19 17:10:00)] was greater than the threshold (10000.0) (minimum 1 datapoint for OK -> ALARM transition).", "reasonData": "{\"version\":\"1.0\",\"queryDate\":\"2019-10-02T17:20:48.551+0000\",\"startDate\":\"2019-10-02T17:10:00.000+0000\",\"period\":300,\"recentDatapoints\":[45628.0],\"threshold\":10000.0}", "timestamp": "2019-10-02T17:20:48.554+0000", "value": "ALARM" } } }
State change for an anomaly detection alarm
{ "version": "0", "id": "daafc9f1-bddd-c6c9-83af-74971fcfc4ef", "detail-type": "CloudWatch Alarm State Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2019-10-03T16:00:04Z", "region": "us-east-1", "resources": ["arn:aws:cloudwatch:us-east-1:123456789012:alarm:EC2 CPU Utilization Anomaly"], "detail": { "alarmName": "EC2 CPU Utilization Anomaly", "state": { "value": "ALARM", "reason": "Thresholds Crossed: 1 out of the last 1 datapoints [0.0 (03/10/19 15:58:00)] was less than the lower thresholds [0.020599444741798756] or greater than the upper thresholds [0.3006915352732461] (minimum 1 datapoint for OK -> ALARM transition).", "reasonData": "{\"version\":\"1.0\",\"queryDate\":\"2019-10-03T16:00:04.650+0000\",\"startDate\":\"2019-10-03T15:58:00.000+0000\",\"period\":60,\"recentDatapoints\":[0.0],\"recentLowerThresholds\":[0.020599444741798756],\"recentUpperThresholds\":[0.3006915352732461]}", "timestamp": "2019-10-03T16:00:04.653+0000" }, "previousState": { "value": "OK", "reason": "Thresholds Crossed: 1 out of the last 1 datapoints [0.166666666664241 (03/10/19 15:57:00)] was not less than the lower thresholds [0.0206719426210418] or not greater than the upper thresholds [0.30076870222143803] (minimum 1 datapoint for ALARM -> OK transition).", "reasonData": "{\"version\":\"1.0\",\"queryDate\":\"2019-10-03T15:59:04.670+0000\",\"startDate\":\"2019-10-03T15:57:00.000+0000\",\"period\":60,\"recentDatapoints\":[0.166666666664241],\"recentLowerThresholds\":[0.0206719426210418],\"recentUpperThresholds\":[0.30076870222143803]}", "timestamp": "2019-10-03T15:59:04.672+0000" }, "configuration": { "description": "Goes into alarm if CPU Utilization is out of band", "metrics": [{ "id": "m1", "metricStat": { "metric": { "namespace": "AWS/EC2", "name": "CPUUtilization", "dimensions": { "InstanceId": "i-12345678901234567" } }, "period": 60, "stat": "Average" }, "returnData": true }, { "id": "ad1", "expression": "ANOMALY_DETECTION_BAND(m1, 0.8)", "label": "CPUUtilization (expected)", "returnData": true }] } } }
State change for a composite alarm with a suppressor alarm
{ "version": "0", "id": "d3dfc86d-384d-24c8-0345-9f7986db0b80", "detail-type": "CloudWatch Alarm State Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-07-22T15:57:45Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServiceAggregatedAlarm" ], "detail": { "alarmName": "ServiceAggregatedAlarm", "state": { "actionsSuppressedBy": "WaitPeriod", "actionsSuppressedReason": "Actions suppressed by WaitPeriod", "value": "ALARM", "reason": "arn:aws:cloudwatch:us-east-1:123456789012:alarm:SuppressionDemo.EventBridge.FirstChild transitioned to ALARM at Friday 22 July, 2022 15:57:45 UTC", "reasonData": "{\"triggeringAlarms\":[{\"arn\":\"arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServerCpuTooHigh\",\"state\":{\"value\":\"ALARM\",\"timestamp\":\"2022-07-22T15:57:45.394+0000\"}}]}", "timestamp": "2022-07-22T15:57:45.394+0000" }, "previousState": { "value": "OK", "reason": "arn:aws:cloudwatch:us-east-1:123456789012:alarm:SuppressionDemo.EventBridge.Main was created and its alarm rule evaluates to OK", "reasonData": "{\"triggeringAlarms\":[{\"arn\":\"arn:aws:cloudwatch:us-east-1:123456789012:alarm:TotalNetworkTrafficTooHigh\",\"state\":{\"value\":\"OK\",\"timestamp\":\"2022-07-14T16:28:57.770+0000\"}},{\"arn\":\"arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServerCpuTooHigh\",\"state\":{\"value\":\"OK\",\"timestamp\":\"2022-07-14T16:28:54.191+0000\"}}]}", "timestamp": "2022-07-22T15:56:14.552+0000" }, "configuration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "actionsSuppressor": "ServiceMaintenanceAlarm", "actionsSuppressorWaitPeriod": 120, "actionsSuppressorExtensionPeriod": 180 } } }
Creation of a composite alarm
{ "version": "0", "id": "91535fdd-1e9c-849d-624b-9a9f2b1d09d0", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-03-03T17:06:22Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServiceAggregatedAlarm" ], "detail": { "alarmName": "ServiceAggregatedAlarm", "operation": "create", "state": { "value": "INSUFFICIENT_DATA", "timestamp": "2022-03-03T17:06:22.289+0000" }, "configuration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "alarmName": "ServiceAggregatedAlarm", "description": "Aggregated monitor for instance", "actionsEnabled": true, "timestamp": "2022-03-03T17:06:22.289+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }
Creation of a composite alarm with a suppressor alarm
{ "version": "0", "id": "454773e1-09f7-945b-aa2c-590af1c3f8e0", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-07-14T13:59:46Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServiceAggregatedAlarm" ], "detail": { "alarmName": "ServiceAggregatedAlarm", "operation": "create", "state": { "value": "INSUFFICIENT_DATA", "timestamp": "2022-07-14T13:59:46.425+0000" }, "configuration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "actionsSuppressor": "ServiceMaintenanceAlarm", "actionsSuppressorWaitPeriod": 120, "actionsSuppressorExtensionPeriod": 180, "alarmName": "ServiceAggregatedAlarm", "actionsEnabled": true, "timestamp": "2022-07-14T13:59:46.425+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }
Update of a metric alarm
{ "version": "0", "id": "bc7d3391-47f8-ae47-f457-1b4d06118d50", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-03-03T17:06:34Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServerCpuTooHigh" ], "detail": { "alarmName": "ServerCpuTooHigh", "operation": "update", "state": { "value": "INSUFFICIENT_DATA", "timestamp": "2022-03-03T17:06:13.757+0000" }, "configuration": { "evaluationPeriods": 1, "threshold": 80, "comparisonOperator": "GreaterThanThreshold", "treatMissingData": "ignore", "metrics": [ { "id": "86bfa85f-b14c-ebf7-8916-7da014ce23c0", "metricStat": { "metric": { "namespace": "AWS/EC2", "name": "CPUUtilization", "dimensions": { "InstanceId": "i-12345678901234567" } }, "period": 300, "stat": "Average" }, "returnData": true } ], "alarmName": "ServerCpuTooHigh", "description": "Goes into alarm when server CPU utilization is too high!", "actionsEnabled": true, "timestamp": "2022-03-03T17:06:34.267+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] }, "previousConfiguration": { "evaluationPeriods": 1, "threshold": 70, "comparisonOperator": "GreaterThanThreshold", "treatMissingData": "ignore", "metrics": [ { "id": "d6bfa85f-893e-b052-a58b-4f9295c9111a", "metricStat": { "metric": { "namespace": "AWS/EC2", "name": "CPUUtilization", "dimensions": { "InstanceId": "i-12345678901234567" } }, "period": 300, "stat": "Average" }, "returnData": true } ], "alarmName": "ServerCpuTooHigh", "description": "Goes into alarm when server CPU utilization is too high!", "actionsEnabled": true, "timestamp": "2022-03-03T17:06:13.757+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }
Update of a composite alarm with a suppressor alarm
{ "version": "0", "id": "4c6f4177-6bd5-c0ca-9f05-b4151c54568b", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-07-14T13:59:56Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServiceAggregatedAlarm" ], "detail": { "alarmName": "ServiceAggregatedAlarm", "operation": "update", "state": { "actionsSuppressedBy": "WaitPeriod", "value": "ALARM", "timestamp": "2022-07-14T13:59:46.425+0000" }, "configuration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "actionsSuppressor": "ServiceMaintenanceAlarm", "actionsSuppressorWaitPeriod": 120, "actionsSuppressorExtensionPeriod": 360, "alarmName": "ServiceAggregatedAlarm", "actionsEnabled": true, "timestamp": "2022-07-14T13:59:56.290+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] }, "previousConfiguration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "actionsSuppressor": "ServiceMaintenanceAlarm", "actionsSuppressorWaitPeriod": 120, "actionsSuppressorExtensionPeriod": 180, "alarmName": "ServiceAggregatedAlarm", "actionsEnabled": true, "timestamp": "2022-07-14T13:59:46.425+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }
Deletion of a metric math alarm
{ "version": "0", "id": "f171d220-9e1c-c252-5042-2677347a83ed", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-03-03T17:07:13Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:TotalNetworkTrafficTooHigh" ], "detail": { "alarmName": "TotalNetworkTrafficTooHigh", "operation": "delete", "state": { "value": "INSUFFICIENT_DATA", "timestamp": "2022-03-03T17:06:17.672+0000" }, "configuration": { "evaluationPeriods": 1, "threshold": 10000, "comparisonOperator": "GreaterThanThreshold", "treatMissingData": "ignore", "metrics": [{ "id": "m1", "metricStat": { "metric": { "namespace": "AWS/EC2", "name": "NetworkIn", "dimensions": { "InstanceId": "i-12345678901234567" } }, "period": 300, "stat": "Maximum" }, "returnData": false }, { "id": "m2", "metricStat": { "metric": { "namespace": "AWS/EC2", "name": "NetworkOut", "dimensions": { "InstanceId": "i-12345678901234567" } }, "period": 300, "stat": "Maximum" }, "returnData": false }, { "id": "e1", "expression": "SUM(METRICS())", "label": "Total Network Traffic", "returnData": true } ], "alarmName": "TotalNetworkTrafficTooHigh", "description": "Goes into alarm if total network traffic exceeds 10Kb", "actionsEnabled": true, "timestamp": "2022-03-03T17:06:17.672+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }
Deletion of a composite alarm with a suppressor alarm
{ "version": "0", "id": "e34592a1-46c0-b316-f614-1b17a87be9dc", "detail-type": "CloudWatch Alarm Configuration Change", "source": "aws.cloudwatch", "account": "123456789012", "time": "2022-07-14T14:00:01Z", "region": "us-east-1", "resources": [ "arn:aws:cloudwatch:us-east-1:123456789012:alarm:ServiceAggregatedAlarm" ], "detail": { "alarmName": "ServiceAggregatedAlarm", "operation": "delete", "state": { "actionsSuppressedBy": "WaitPeriod", "value": "ALARM", "timestamp": "2022-07-14T13:59:46.425+0000" }, "configuration": { "alarmRule": "ALARM(ServerCpuTooHigh) OR ALARM(TotalNetworkTrafficTooHigh)", "actionsSuppressor": "ServiceMaintenanceAlarm", "actionsSuppressorWaitPeriod": 120, "actionsSuppressorExtensionPeriod": 360, "alarmName": "ServiceAggregatedAlarm", "actionsEnabled": true, "timestamp": "2022-07-14T13:59:56.290+0000", "okActions": [], "alarmActions": [], "insufficientDataActions": [] } } }