How to Import an AWS CloudWatch Metric Alarm into Terraform

Import AWS CloudWatch Metric Alarm with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Amazon CloudWatch resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS CloudWatch Metric Alarm to managed Terraform.

terraback scan all aws --region us-east-1

terraback aws import --method bulk

The Terraform import block

Terraback emits a Terraform 1.5+ import block like the one below. Because the block lives in your configuration, the import is reviewable in a pull request and repeatable across environments.

import {
  to = aws_cloudwatch_metric_alarm.high_cpu
  id = "high-cpu-web"
}

Example aws_cloudwatch_metric_alarm configuration

Here is a realistic AWS CloudWatch Metric Alarm block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_cloudwatch_metric_alarm" "high_cpu" {
  alarm_name          = "high-cpu-web"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 2
  metric_name         = "CPUUtilization"
  namespace           = "AWS/EC2"
  period              = 300
  statistic           = "Average"
  threshold           = 80
  alarm_actions       = ["arn:aws:sns:us-east-1:123456789012:alerts"]
}

Gotchas when importing a AWS CloudWatch Metric Alarm

• Import by the alarm name, not by ARN.
• Composite alarms are a different Terraform resource (aws_cloudwatch_composite_alarm), so import those separately.
• The SNS topics referenced in alarm_actions and ok_actions are separate resources; importing the alarm does not import them.
• metric alarms based on a metric math query use one or more metric_query blocks instead of a single metric_name; reconstruct the math expression carefully.

Doing it manually with terraform import

The native approach is to write the aws_cloudwatch_metric_alarm block by hand, then run terraform import aws_cloudwatch_metric_alarm.example <import-id> for every resource, one at a time. That works for a handful of resources, but it does not scale: you author all the HCL yourself and repeat the command for each item. Terraback generates the HCL and the import blocks for your whole account in one pass.

Import other AWS resources