Add @elisasre/cdk-constructs as a dependency of your CDK project and import the desired construct.

Alarm with tags extends the standard CDK alarm construct by allowing tagging of alarms, which Cloudformation does not currently support out of the box.

declare const fn: lambda.Function;

const minuteErrorRate = fn.metricErrors({
  statistic: cloudwatch.Stats.AVERAGE,
  period: Duration.minutes(1),
  label: 'Lambda failure rate'
});

const alarm = new AlarmWithTags(this, 'myalarm', {
    evaluationPeriods: 3,
    metric: minuteErrorRate,
    threshold: 1,
    comparisonOperator: cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
});

Tags.of(alarm).add('foo', 'bar');

declare const fn: lambda.Function;

const minuteErrorRate = fn.metricErrors({
  statistic: cloudwatch.Stats.AVERAGE,
  period: Duration.minutes(1),
  label: 'Lambda failure rate'
});

const alarm = minuteErrorRate.createAlarm(this, 'myalarm', {
    evaluationPeriods: 3,
    threshold: 1,
    comparisonOperator: cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
});

const myTaggedAlarm = AlarmWithTags.fromArn(this, 'myalarmwithtags', alarm.alarmArn);

Tags.of(myTaggedAlarm).add('foo', 'bar');

API reference