Add etcdctl to image

[aaronfern]

What this PR does / why we need it: This PR adds etcdctl to the ops image so that it can be used to interact with and debug the etcd database

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

Release note:

Added etcdctl to the image

[petersutter]

Hi @aaronfern, this change will increase the image size by 16MB. Would you mind to create an installer script for it instead? similar like we have it for k9s? https://github.com/gardener/ops-toolbelt/blob/master/hacks/install_k9s Then it can be installed on demand but the images size will not increase noticeably

[plkokanov]

Thanks for the PR. The etcdctl command seems to be 44 MB in size. We try to keep the ops-toolbelt as minimal as possible. Do you think that this command will be used very often? Perhaps you could make it so that it is installed on demand, check https://github.com/gardener/ops-toolbelt/blob/master/dotfiles/.install_on_demand/.wireguard and https://github.com/gardener/ops-toolbelt/blob/3ef1fa4427a4b9a1a11c92ccbde450f9dabfa868/dockerfile-configs/common-components.yaml#L117-L120 or https://github.com/gardener/ops-toolbelt/blob/master/hacks/install_k9s

I'm guessing that we would have to start the ops-toolbelt as a sidecar ephemeral container in the etcd pod or as a container in the same network and fs namespace as the etcd containers if launching it from the node via the ctr command. Is there any way that we can add the default paths where the required certificates for talking to the etcd server are, the default endpoint for the etcd server and set ETCDCTL_API=3 (if that is still necessary)?

[aaronfern]

Thanks for your reviews @petersutter and @plkokanov Yes, it makes sense what y'all have pointed out to. I will make the necessary changes

[plkokanov]

Ping @aaronfern

[aaronfern]

@petersutter @plkokanov I have opened a different PR to introduce an installer script to install etcdctl on demand Hence closing this PR in favour of #96 /close