Added readme with design considerations.

[TBeijen]

PR o'clock

Description

Draft 'Readme-driven-development' PR, addressing #635 (specifically this comment) and feedback in #644.

Feedback welcome. Will add code soon.

Checklist

• Change added to CHANGELOG.md. All changes must be added and breaking changes and highlighted
• CI tests are passing
• README.md has been updated after any changes to variables and outputs. See https://github.com/terraform-aws-modules/terraform-aws-eks/#doc-generation

[dpiddockcmp]

I was fiddling around with trying to move this code into a submodule. Current progress has been put in PR #650.

I assumed that the submodule would only be used by the parent module as a way to isolate code. No way to include a module multiple times at runtime yet, so all appropriate multiple resources are created inside the module.

I have concerns that there would be too much specific plumbing required to have the module used stand alone by the user.

[TBeijen]

I have concerns that there would be too much specific plumbing required to have the module used stand alone by the user.

I'll take a look (probably after the weekend). Imo there's various angles to look at:

• Complexity of module code (maintenance, users looking into module code for usage details)
• Need for users to wire outputs into submodule inputs.
• Implicit pros/cons, e.g. the current inability to remove the first worker group from a list of worker groups.

I might code a poc to just see how much the plumbing will be.

Having the user repeat a module blocks feels natural. It's using Terraform's concept for re-usable code (modules) instead of re-creating that ourselves within the terraform-aws-eks module. It's wat Cloudposse does.

As for plumbing, the idea crossed my mind to have the parent module (terraform-aws-eks core) output all relevant attributes separately but also wrapped in a map, a sort of 'connector'. Then wire that into the submodule. Something like:

module "my_cluster" {
  source          = "terraform-aws-modules/eks/aws"
  cluster_name    = "my-cluster"
}

module "managed_group_a" {
  source          = "terraform-aws-modules/eks/aws//modules/managed_nodes"
  node_group_name = "managed-a"

  parent_module_attributes = module.my_cluster.attributes_combined
}

Naming not so good. And might very well best remain an idea.

[stale]

This PR has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
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[barryib]

@TBeijen this is still in draft and sounds like this it goes stale.

Closing this. Please feel free to reopen when work resumes.

[github-actions]

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