support metrics collection in scaling config for unmanaged node groups

[saada]

Description

closes #827

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the site/content directory)
• Manually tested
• Added labels for change area (e.g. area/nodegroup), target version (e.g. version/0.12.0) and kind (e.g. kind/improvement)
• Make sure the title of the PR is a good description that can go into the release notes

[sayboras]

@saada understand that this is still in draft condition, are you planning to add the mapping between configuration struct to cloudformation for metric collection as well ?

[saada]

@sayboras , thanks for the feedback! Where can I do the mapping to cloudformation? Which directory?

[sayboras]

@sayboras , thanks for the feedback! Where can I do the mapping to cloudformation? Which directory?

You can find it here https://github.com/weaveworks/eksctl/blob/master/pkg/cfn/builder/nodegroup.go#L263.

I just have a quick look, seems like this feature will be only for un-managed node group. CF for managed nodegroup didn't support metric related attribute yet https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-eks-nodegroup-scalingconfig.html

[cPu1]

I left some comments but otherwise LGTM. Thanks for the PR!

[martina-if]

Can we add some tests for this? :) I think you can probably extend one of the existing tests for this.

[sayboras]

@saada LGTM 💯

[martina-if]

I think we shouldn't couple the API schema of eksctl with the cloudformation template directly. It could happen in the future that the schema is extended or changed to a new version and that would break the backend part of eksctl.

Even though it's verbose I think the right thing to do is to recreate the CFN struct like we do in line 287 with mixedInstancesPolicy()

[saada]

@martina-if , can you please verify the latest changes?

[dholbach]

Once rebased on master, this should pass the link checker again.

[saada]

Successfully tested this manually with the following config:

---
apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: mahmoud-cluster-1
  region: eu-west-2

nodeGroups:
  - name: ng-1
    instanceType: t2.medium
    desiredCapacity: 1
    asgMetricsCollection:
      - granularity: 1Minute
        metrics:
          - GroupMinSize
          - GroupMaxSize
          - GroupDesiredCapacity
          - GroupInServiceInstances
          - GroupPendingInstances
          - GroupStandbyInstances
          - GroupTerminatingInstances
          - GroupTotalInstances

[saada]