Update config to use KubeletConfig in line with official AMI

[errm]

see: awslabs/amazon-eks-ami#90

This should fix #49 that I think is cased by relying on deprecated
kubelet flags.

[errm]

FYI: @ettiee

[codecov]

Codecov Report

Merging #50 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #50   +/-   ##
=======================================
  Coverage   90.82%   90.82%           
=======================================
  Files           7        7           
  Lines         229      229           
=======================================
  Hits          208      208           
  Misses         13       13           
  Partials        8        8

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[mtpereira]

@errm So this will break support for older Kubernetes versions, right? This should be mentioned in the README and/or in the release notes of this particular version. Also, this release should be a minor SemVer upgrade.

[errm]

I think this should still work with k8s 1.10 ... I will need to test that... but this config file was added in 1.10 ...

[errm]

Yep confirmed this landed in 1.10 https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/#before-you-begin

[errm]

Also since the major version is still 0 we can do whatever we like anyway https://semver.org/#spec-item-4

[mtpereira]

Yep confirmed this landed in 1.10 https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/#before-you-begin

How far back are we willing to keep ekstrap working?

[errm]

How far back are we willing to keep ekstrap working?

It only needs to work with the versions you can currently run on EKS ... currently that means 1.10 and 1.11 we should just support whatever AWS does...