Fix json tags for etcd worker config

[timuthy]

How to categorize this PR?

/area control-plane
/kind api-change
/needs cherry-pick

What this PR does / why we need it:
This PR amends the struct tags for workers configuration in the etcdConfig.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:
This is an incompatible API change. However, the example as well as chart values assume that the fields were called workers before, so the likelihood to break someone is rather small. From an end-user perspective setting the values "just" didn't work.

Release note:

An issue has been fixed that prevented etcd worker counts from being set correctly in the `GardenletConfiguration`.

[ialidzhikov]

lgtm for the tag name change, but I have comments for discrepancies in the defaults.

[ialidzhikov]

Not strictly related to this change but I think there is something wrong with the defaults:

gardener/pkg/operation/botanist/component/etcd/bootstrap.go

Lines 330 to 332 in c52af1b

	if config.ETCDController != nil {
	command = append(command, "--workers="+strconv.FormatInt(pointer.Int64Deref(config.ETCDController.Workers, 50), 10))
	}

.

I don't see any explicit defaulting in g/g for this field. There is only defaulting to 50 when ETCDController is non-nil and Workers is nil. Does the default 3 actually comes from etcd-druid? If yes, doesn't it make sense to update the above handling to use 3 instead of 50?

[timuthy]

Good point.

There is only defaulting to 50 when ETCDController is non-nil and Workers is nil.

This is actually the default that is meant here. We should add it to the defaulting logic in pkg/gardenlet/apis/config/v1alpha1/defaults.go which was missed in the previous PR. I propose to do this in a future PR, @abdasgupta can take over when he returned.

If yes, doesn't it make sense to update the above handling to use 3 instead of 50?

50 was the hard-coded default earlier and if we now set it to 3 it will break operators who rely on the higher value. Therefore, 50 was chosen here. I will update the comment.

[ialidzhikov]

This is actually the default that is meant here. We should add it to the defaulting logic in pkg/gardenlet/apis/config/v1alpha1/defaults.go which was missed in the previous PR. I propose to do this in a future PR, @abdasgupta can take over when he returned.

Can you open an issue about it? There are still some discrepancies - it you don't specify any default config, then for the custodian controller 3 will be used (default in etcd-druid). But if you specify empty custodianController config, then 10 will be used (default in the etcd component in gardener). Let's better follow-up with separate issue - PR.

[ialidzhikov]

/lgtm
/squash