Reduce default ETCD volume size and/or make it easy configurable

[klausenbusk]

1. Describe IN DETAIL the feature/behavior/change you would like to see.

The default ETCD volume size at the moment is 20GB:

kops/pkg/model/master_volumes.go

Line 38 in dc4a1a3

DefaultEtcdVolumeSize = 20

Which I think is way overkill for most clusters and a waste of money (DO example: 3 masters * 20GB disk * 2 * 0,1 = 12$/month). Lets change it to something more reasonable, 5GB maybe? and make it easily configurable without changing the config files by hand.

2. Feel free to provide a design supporting your feature request.

Lets add a kops create cluster parameter to control DefaultEtcdVolumeSize instead of hardcoding it.

cc @andrewsykim

[ValeryNo]

Agreed. After 5 months our etcd volumes are <500mb

[marshallford]

I am also interested in this parameter being added.

[ghost]

any update on this guys, ,or is there any easy solution to this.

[lpf190]

we also need this function

[mikesplain]

Hi all, this is actually already implemented, though not documented (which I've done in #5692). Hope this helps!