How to Import an AWS SSM Maintenance Window into Terraform

Import AWS SSM Maintenance Window with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the AWS Systems Manager resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS SSM Maintenance Window 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_ssm_maintenance_window.patch
  id = "mw-0a1b2c3d4e5f6a7b8"
}

Example aws_ssm_maintenance_window configuration

Here is a realistic AWS SSM Maintenance Window block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_ssm_maintenance_window" "patch" {
  name     = "weekly-patch"
  schedule = "cron(0 2 ? * SUN *)"
  duration = 4
  cutoff   = 1
}

Gotchas when importing a AWS SSM Maintenance Window

• Import by the mw- maintenance window ID, not the window name.
• The window is only the schedule; the instances it acts on (aws_ssm_maintenance_window_target) and the work it runs (aws_ssm_maintenance_window_task) are separate resources you import on their own.
• duration is in hours and cutoff is the number of hours before the end when no new tasks may start, so cutoff must be less than duration.
• schedule uses SSM cron/rate syntax with a required timezone consideration; set schedule_timezone explicitly or the window runs in UTC.

Doing it manually with terraform import

The native approach is to write the aws_ssm_maintenance_window block by hand, then run terraform import aws_ssm_maintenance_window.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