feat: Allow to choose launch template version for Managed Node Groups when create_launch_template is set to true

[ArchiFleKs]

PR o'clock

Description

By default choose latest LT version. This trigger a rollout of all the instances. I noticed this because of the description change here

This PR allow to override launch template version to postpone instances rollout if needed

Checklist

• README.md has been updated after any changes to variables and outputs. See https://github.com/terraform-aws-modules/terraform-aws-eks/#doc-generation

[barryib]

😢

In docs https://docs.aws.amazon.com/eks/latest/userguide/launch-templates.html it says:

When you update your node group to a different version of your launch template, all of the nodes in the group are recycled to match the new configuration of the specified launch template version. Existing node groups that do not use a custom launch template can't be updated directly. Rather, you must create a new node group with a custom launch template to do so.

[ArchiFleKs]

😢

In docs https://docs.aws.amazon.com/eks/latest/userguide/launch-templates.html it says:

When you update your node group to a different version of your launch template, all of the nodes in the group are recycled to match the new configuration of the specified launch template version. Existing node groups that do not use a custom launch template can't be updated directly. Rather, you must create a new node group with a custom launch template to do so.

@barryib Do you see any issue with that ?

For me when not using Create/Custom LT the only thing that is going to trigger an update if changing the label maybe and the version right ?

[barryib]

I was just wondering how user will get the launch_template_version if it's created directly by the module ? They have to go through the aws cli or aws console ?

[ArchiFleKs]

Yes I think they can see it in the TF or in cli/console. Most of the time if think you want to upgrade (that's one of the perk of MNG vs Self managed without instance refresh) but it might be useful when you have large pool and do not want to trigger an upgrade yet

[barryib]

I just noticed that launch_template_version = "$Latest" by default https://github.com/terraform-aws-modules/terraform-aws-eks/blob/master/local.tf#L104. In that case, should we need this ternary evaluation ?

Does version = each.value["launch_template_version"] enough ?

[ArchiFleKs]

Yes it should be, fixed

[jaimehrubiks]

#1446

[barryib]

@barryib Do you see any issue with that ?

I was just saying that it is intended behavior ^^.

For me when not using Create/Custom LT the only thing that is going to trigger an update if changing the label maybe and the version right ?

I think you're right. I don't use MNG at all (for now).

[barryib]

Thanks @ArchiFleKs for your contribution.

[barryib]

Just released it in v17.1.0

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues. If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.