Upgrading from v3.4.9 to v3.4.10 requires manual action

[invidian]

After upgrading existing cluster from version v3.4.9 to v.3.4.10, etcd fails to start with following error:

{"level":"fatal","ts":"2020-07-17T07:11:27.596Z","caller":"etcdmain/etcd.go:271","msg":"discovery failed","error":"cannot access data directory: directory \"/theory-controllers-1.etcd\",\"drwxr-xr-x\" exist without desired file permission \
"-rwx------\".","stacktrace":"go.etcd.io/etcd/etcdmain.startEtcdOrProxyV2\n\t/tmp/etcd-release-3.4.10/etcd/release/etcd/etcdmain/etcd.go:271\ngo.etcd.io/etcd/etcdmain.Main\n\t/tmp/etcd-release-3.4.10/etcd/release/etcd/etcdmain/main.go:46\nm
ain.main\n\t/tmp/etcd-release-3.4.10/etcd/release/etcd/main.go:28\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:200"}

To get it to work, manual sudo chmod 0700 execution is required on all members user data directories to get etcd running again. This seems to be a new requirement (or old one, which was not enforced) and it is not mentioned in the changelog nor in the upgrade guide, which was unexpected.

Perhaps this should be documented somewhere?

[tangcong]

@invidian done. previously we only added documentation in 3.5 changelog. thanks.

[spzala]

@invidian thanks for noticing, we modified the master changelog under #11997 but missed 3.4 and 3.3 while cherry-picking it.

[jingyih]

For reference, this issue is fixed by #12242