cloudwatch-stddev-alarm-creator

Retrieves metrics from Cloudwatch, calculates standard deviation, and sets upper and/or lower alarms based on same. Cloudwatch will only calculate a Standard Deviation based alarm using the values within the period measured. This function allows you to calculate the Standard Deviation across a much longer period (e.g. - 12 months) and use that value from thresholding a Cloudwatch alarm.

This Lambda function is designed to be invoked by a Cloudwatch Scheduled Event, but it may be invoked by any Lambda trigger. It ignores the incoming event.

Required Permissions

• cloudwatch:DeleteAlarms
• cloudwatch:GetMetricData
• cloudwatch:ListMetrics
• cloudwatch:PutMetricAlarm

All permissions require * as the resource.

Environment Variables

ALARM_ACTIONS (Optional)

The actions to execute when this alarm transitions to the ALARM state from any other state. Each action is specified as an Amazon Resource Name (ARN), seperated by commas.

ALARM_NAME (Optional)

If present, the name of the alarm will be <ALARM_NAME>/<Dimensions>-<Bound>`. Otherwise, the name will be <METRIC_NAMESPACE>/<METRIC_NAME>/<Dimensions>-<Bound>

BOUNDS (Optional)

The type of alarm threshold(s) to set. Either AlarmHigh, AlarmLow or Both. Defaults to Both.

DATAPOINTS_TO_ALARM (Required)

The number of datapoints that must be breaching to trigger the alarm. This is used only if you are setting an "M out of N" alarm. In that case, this value is the M. For more information, see Evaluating an Alarm in the Amazon CloudWatch User Guide.

EVALUATION_PERIODS (Required)

The number of periods over which data is compared to the specified threshold. If you are setting an alarm that requires that a number of consecutive data points be breaching to trigger the alarm, this value specifies that number.

If you are setting an "M out of N" alarm, this value is the N. An alarm's total current evaluation period can be no longer than one day, so this number multiplied by PERIOD cannot be more than 86,400 seconds.

INSUFFICIENT_DATA_ACTIONS (Optional)

The actions to execute when this alarm transitions to the INSUFFICIENT_DATA state from any other state. Each action is specified as an Amazon Resource Name (ARN), seperated by commas.

METRIC_DIMENSIONS (Optional)

The dimensions for the metric specified in METRIC_NAME. This is a list of dimension name and value pairs (seperated by commas) that are seperated by semicolons. The dimension values may be regular expressions. If not present, all metrics that match METRIC_NAMESPACE and METRIC_NAME will have alarms created for them.

For example: name1,foo.*;name2,bar[1-9]*

METRIC_NAME (Required)

The name for the metric associated with the alarm.

METRIC_NAMESPACE (Required)

The namespace for the metric associated with the alarm.

METRIC_SAMPLE_DAYS (Optional)

The number of days to use to calculate the mean and population standard deviation from. Must be less than 455. Defaults to 15.

METRIC_STAT (Required)

The statistic to use for the metric. It can include any CloudWatch statistic.

METRIC_UNIT (Required)

The unit to use for the metric data points.

NUM_STANDARD_DEVIATION (Optional)

The number of standard deviations used to caluculate high/low thresholds. Default is 3.

OK_ACTIONS (Optional)

The actions to execute when this alarm transitions to an OK state from any other state. Each action is specified as an Amazon Resource Name (ARN) , seperated by commas.

PERIOD (Required)

The length, in seconds, used each time the metric specified in METRIC_NAME is evaluated. Valid values are 10, 30, and any multiple of 60.

An alarm's total current evaluation period can be no longer than one day, so this multiplied by EVALUATION_PERIODS cannot be more than 86,400 seconds.

The actual period used may be changed by METRIC_SAMPLE_DAYS as CloudWatch places certain requirements of period length when retrieving metric data.

TREAT_MISSING_DATA (Optional)

Sets how this alarm is to handle missing data points. One of breaching, notBreaching, ignore or missing. Defaults to missing.

License: APL2