☂️ Etcd ConfigMap changes

[unmarshall]

One ConfigMap is created per etcd (etcd-main and etcd-events) today. We propose to do/relook at the following:

• [ ] Revive https://github.com/gardener/etcd-druid/pull/467 and ensure that the name of the ConfigMap's are consistent with all other resources that are created for an etcd resource. While doing this ensure that the new version of druid which now uses the new name properly reconciles the older configmap's having the older name.
• [ ] Make snapshot-count configurable See impact here. We can retain the default of 75000. Upstream default changes from 10000 to 100,000. We can revisit the current default if need be.
• [ ] #476

[ishan16696]

initial-advertise-peer-urls and advertise-client-urls uses @ as delimiter. This is not really required. Have proper URLs.

open issue for this point: https://github.com/gardener/etcd-druid/issues/476

[shreyas-s-rao]

/assign @anveshreddy18

[ishan16696]

Make snapshot-count configurable See impact here. We can retain the default of 75000. Upstream default changes from 10000 to 100,000. We can revisit the current default if need be.

Increasing the default snapshot-count to 100K is not good as it will leads to more usage of memory. kubeadm uses snapshot-count set to 10k. https://github.com/kubernetes/kubernetes/blob/release-1.20/cmd/kubeadm/app/phases/etcd/local.go#L270 Upstream etcd have also changed the default value of snapshot-count to 10k https://github.com/etcd-io/etcd/pull/15408. They will bring this change in etcd v3.6.