Migrating AWS Batch from Launch Configurations to Launch Templates

AWS Batch Launch Configurations Deprecation

I recently received this message from AWS about the deprecation of Launch Configurations in favor of Launch Templates.

[Notification] EC2 Auto Scaling Launch Configuration Deprecation Notification

Hello,

In 2021, AWS announced the plan to deprecate launch configurations in favor of launch templates. Since that time, continual enhancements have been made to encourage migration to launch templates. This notification contains details about the next step in the launch configuration deprecation process.

Starting on October 1, 2024, you will be unable to create new launch configurations except in AWS Regions where you had a launch configuration in your AWS account or AWS Organizations at some point between July 1, 2024 and October 1, 2024.

Affected accounts will receive the following exception when trying to create a launch configuration through the API or CLI:

UnsupportedOperationException: The launch configuration creation operation is not available in your account. Use launch templates to create configuration templates for your Auto Scaling groups.

Prior to this step, we have already taken the following actions to begin deprecating launch configurations:

• Since January 1, 2023, launch configurations have not been updated with new instance types released after that date. Any new instance types that were released before January 1, 2023 in regions that became available after that date remain inaccessible through launch configurations. To use the latest instance types, users must transition to using launch templates.
• Since January 1, 2023, launch configurations have not received any new EC2 feature updates. To use new EC2 features, users must now use launch templates.
• Since April 1, 2023, new AWS accounts can no longer create launch configurations in the EC2 console. Only accounts created before this date retain access.

We strongly encourage the remaining customers of launch configurations to migrate to launch templates as soon as possible. Our documentation provides guidance on using the console migration tool to convert launch configurations to launch templates [1]. To identify Auto Scaling groups that are still using launch configurations, you can run this script [2].

If you have any questions or concerns, please reach out to AWS Support [3].

[1] https://docs.aws.amazon.com/autoscaling/ec2/userguide/migrate-to-launch-templates.html

[2] > https://github.com/aws-samples/amazon-ec2-auto-scaling-group-examples/tree/main/tools/launch-configuration-inventory

[3] https://aws.amazon.com/support

Sincerely, Amazon Web Services

When I looked into the Launch Configurations I had defined, I was surprised to see that they didn’t have a CloudFormation stack attached. After some digging, I realized that these auto-scaling groups and Launch Configurations were associated with AWS Batch.

When you create a Compute Environment via CloudFormation, AWS Batch creates the auto-scaling groups and Launch Configurations automatically, but does not propagate tags from the parent resources managed by CloudFormation. This can make it difficult to figure out where they came from.

AWS Batch and Launch Configurations

AWS Batch, when used with the BEST_FIT allocation strategy, automatically created autoscaling groups and Launch Configurations to manage the compute environment. Beginning in April 2024, new Compute Environments were created with Launch Templates (the successor to Launch Configurations), but existing Compute Environments continued to use Launch Configurations. From the documentation:

AWS Batch manages AWS resources in your account. Compute environments with the BEST_FIT allocation strategy originally utilized launch configurations by default. However, the use of launch configurations with new AWS accounts will be restricted over time.

Therefore, beginning in late April 2024, newly-created BEST_FIT compute environments will default to launch templates. If your service role lacks permissions to manage launch templates, AWS Batch may continue to utilize launch configurations. Existing compute environments will continue to use launch configurations.

According to AWS Support, AWS Batch has an exemption to the Launch Configuration deprecation and customers will eventually be transparently upgraded. However, you can silence the deprecation sooner by recreating the Compute Environment.

Recreate the AWS Batch Compute Environment

Here’s what I did to resolve the issue:

1. Create a new Compute Environment via AWS CDK using the same parameters. If you’re specifying a name for your environment, you’ll need to use a new name so it’s unique.
2. In a pre-production environment, update the Job Queue to point at the newly created Compute Environment.
3. Test that jobs still run successfully against the new Compute Environment.
4. Change the production Job Queue to point at the new Compute Environment.
5. Allow jobs to run for a few days. At this point, the legacy Compute Environment still exists, in case we need to roll back to the existing configuration.
6. Delete the legacy Compute Environment from all environments. When you delete the Compute Environment, it will clean up the auto-scaling groups and legacy Launch Configurations associated with it.

That’s it! You’ve now upgraded your AWS Batch Compute Environment to use Launch Templates instead of legacy Launch Configurations.