Support EKS node group update add-on "AddOnMNG/NGUpdate"

[gyuho]

Scale up existing ng/mng from x to y.

[gyuho]

• https://docs.aws.amazon.com/cli/latest/reference/eks/update-nodegroup-config.html
• https://docs.aws.amazon.com/cli/latest/reference/eks/update-nodegroup-version.html
• And define our own API for scale up/down regular node group

[gyuho]

https://docs.aws.amazon.com/cli/latest/reference/eks/update-nodegroup-config.html

We can define in eksconfig/add-on-managed-node-groups.go:

type MNGScaleConfig struct {
   minSize=integer,maxSize=integer,desiredSize=integer
}

type MNG struct {
   ...

   ScaleConfigs []MNGScaleConfig `json:"scale-configs"`
}

(to be executed in sequence, after mng is created)

https://docs.aws.amazon.com/cli/latest/reference/eks/update-nodegroup-version.html

We can do the same thing as eksconfig/add-on-cluster-version-upgrade.go (implemented in eks/cluster/version-upgrade/):

type MNGVersionUpgrade struct {
	// Enable is 'true' to create this add-on.
	Enable bool `json:"enable"`
	// Created is true when the resource has been created.
	// Used for delete operations.
	Created         bool               `json:"created" read-only:"true"`
	TimeFrameCreate timeutil.TimeFrame `json:"time-frame-create" read-only:"true"`

	// Version is the version of EKS Kubernetes "cluster".
	// If empty, set default version.
	Version      string  `json:"version"`
	VersionValue float64 `json:"version-value" read-only:"true"`
}

type MNG struct {
   ...

   VersionUpgrade *MNGVersionUpgrade `json:"version-upgrade"`
}

And define our own API for scale up/down regular node group

Should be added to ec2config.ASG:

type ASGScaleConfig struct {
   minSize=integer,maxSize=integer,desiredSize=integer
}

type ASG struct {
   ...

   ScaleConfigs []ASGScaleConfig `json:"scale-configs"`
}

[gyuho]

Done via #106.