For google kubernetes engine, the master node, and ETCD cluster is abstracted away from the me the user.
Most of the ETCD backup guide (such as) assumes I have the endpoint or file system access to perform backups respectively.
As such - how do I perform such a backup, and restoration of ETCD in GKE?
Or would GKE provide subsequently a managed backup/restore service similar to cloud SQL?
Also if a full backup is not possible, even namespace backups will be great.
To clarify the scenario to guard against is not "if google goes down", but "if we do something stupid"
GKE backend is completely managed and thus, there is no way to access the etcd API. Even if you could access the cluster etcd, there are no guarantees of backwards compatibility for the storage backend. So the storage layer could change.
You'll have to use the kubernetes API which is backwards compatible for any backups you might want. There is some discussion on the kubernetes users google group here which should clarify this further.