About patching schedules using maintenance windows - AWS Systems Manager

About patching schedules using maintenance windows

After you configure a patch baseline (and optionally a patch group), you can apply patches to your node by using a maintenance window. A maintenance window can reduce the impact on server availability by letting you specify a time to perform the patching process that doesn't interrupt business operations. A maintenance window works like this:

  1. Create a maintenance window with a schedule for your patching operations.

  2. Choose the targets for the maintenance window by specifying the Patch Group or PatchGroup tag for the tag name, and any value for which you have defined Amazon Elastic Compute Cloud (Amazon EC2) tags, for example, "web servers" or "US-EAST-PROD. (You must use PatchGroup, without a space, if you have allowed tags in EC2 instance metadata.

  3. Create a new maintenance window task, and specify the AWS-RunPatchBaseline document.

When you configure the task, you can choose to either scan nodes or scan and install patches on the nodes. If you choose to scan nodes, Patch Manager, a capability of AWS Systems Manager, scans each node and generates a list of missing patches for you to review.

If you choose to scan and install patches, Patch Manager scans each node and compares the list of installed patches against the list of approved patches in the baseline. Patch Manager identifies missing patches, and then downloads and installs all missing and approved patches.

If you want to perform a one-time scan or install to fix an issue, you can use Run Command to call the AWS-RunPatchBaseline document directly.


After installing patches, Systems Manager reboots each node. The reboot is required to make sure that patches are installed correctly and to ensure that the system didn't leave the node in a potentially bad state. (Exception: If the RebootOption parameter is set to NoReboot in the AWS-RunPatchBaseline document, the managed node isn't rebooted after Patch Manager runs. For more information, see Parameter name: RebootOption.)