[heyitsanthony]

Fixes #6336

[xiang90]

lgtm

[richinsr]

FYI, anyone using domain names and upgrading to the published 3.0.8 release will have their cluster break. Thoughts about cutting a new release with the reverted merge included?

[heyitsanthony]

@richinsr the revert will be in 3.0.9 this Friday. How is it breaking the cluster on upgrade? It will only reject the flags starting an upgraded member-- the cluster can stay on 3.0.7 if the 3.0.8 upgrade doesn't take.

[richinsr]

@heyitsanthony I was working on upgrading a cluster today for someone else and the first node that was upgraded to 3.0.8 failed to start given the config uses a domain name for listen-peer-urls. It took a bit to track down this thread to realize that the config is wrong in the fist place (cluster was setup by someone else). If enforcement of not using domain names will be addressed in 3.1 then anyone in my same boat who upgrades to 3.0.8 will encounter a failure but every other release in the 3.0.x family will work. Maybe it is as simple as adding a note to https://github.com/coreos/etcd/blob/master/NEWS

[heyitsanthony]

@richinsr it'll be enforced in 3.2. 3.1 will just have a warning.