EKS Node Launch Template support

[dotCipher]

Describe the Feature

The eks-node-group resource now supports launch templates.

See associated aws post as well as eks launch templates docs for more information.

Expected Behavior

1. Define launch_template somewhere in call-site of this module
2. Reference launch_template output within attribute of cloudposse/terraform-aws-eks-node-group

Use Case

I'd like to be able to add user data (ie. install SSM agent) to my EKS managed node groups, and I am unable to do that without adding launch templates.

Describe Ideal Solution

There should be a launch_template attribute that is 'settable' for the module

Alternatives Considered

Only alternative would be to remove dependency to this module and hand write it 😛

Additional Context

• AWS discussion of adding launch template support to EKS
• launch_template terraform resource

[dotCipher]

Seems like this might be dependent on the version bump PR: #25

[dotCipher]

FWIW, I'd gladly help write the PR, can someone point me in the right direction for the testing workflow used? ie. what commands to run, etc?

[danjbh]

I'm going to push to get this knocked out today and would appreciate another set of eyes & testing when the new PR ready. I'll post it here once it's ready. Stay tuned!

[danjbh]

Hey there @dotCipher , I have a first draft of this prepped that allows you to...

1. Completely override the launch template by passing aws_launch_template.foo.id and launch_template.foo.version to the module
2. Override only the userdata by passing it to the module as a typical, b64 encoded string
3. Not do anything extra and we'll use a minimal, default aws_launch_template (and default userdata) -- the primary enhancement here being that it adds the tag_specifications config option that will pass on our tags to instances, volumes, and elastic-gpu

Beyond that, there is one snag I ran into w/ the instance types -- a launch template won't accept a list of instance types, which the module is currently accepting. The aws_eks_node_group resource actually accepts a list, although the documentation says it can only handle a single value currently (woohoo).

Anyhow, I need to sort through that bit before I can push another PR and I may not have it ready until tomorrow. But definitely let me know your thoughts on the above in the meantime!

[danjbh]

Hey there @dotCipher , feel free to check out #27

[dotCipher]

Awesome, thanks @danjbh! I posted some questions on the PR

[danjbh]

Hey @dotCipher , just a friendly warning here -- I found some issues w/ the latest version of the module after merging that PR. I would hold off on using the module until I can get things fixed.

[dotCipher]

Thanks for the heads-up @danjbh, I'll keep a look out for your fix

[dotCipher]

Out of curiosity, what were the issues you found?

[danjbh]

Out of curiosity, what were the issues you found?

I didn't realize that if we don't specify our own custom AMI, that it actually appends it's own bootstrap.sh script in userdata AFTER the userdata script that we supply. So it was effectively trying to run bootstrap.sh twice, which was... undesirable :)

[dotCipher]

Does the AMI get set to custom version if the userdata is set? Would I be able to use the module as-is now if I am not using a custom AMI?

[danjbh]

Nope, we can set our userdata without specifying a custom AMI, so you should be able to install your SSM agent using 0.10.0 of the module by setting the before userdata variable.

[dotCipher]

Ah ok great thanks!

[dotCipher]

Feel free to close this out then, appreciate the help! I'll follow up with a new ticket if I have any issues