From the docs: https://github.com/coreos/etcd/blob/master/Documentation/op-guide/configuration.md#--listen-peer-urls etcd should not allow domain names in listen-peer-urls, but I'm finding that it does.

I don't actually know if this causes any problems, but it seems like it shouldn't be allowed regardless if it does work.

Unfortunately, this was found in my setup of etcd 2.3.2 so I didn't test with 3.0.0 nor 2.3.7 since neither are included in the CoreOS image and I didn't have time to check if this is true of the latest releases. However, I believe it does work, as @dghubble's examples in coreos-baremetal set up etcd using the domain name as peer URLs, which he says has been working.

My etcd2.service is located in the gist along with logs. As you can see, I'm getting no validation errors, and etcd proudly proclaims it's listening on a domain name + port.

https://gist.github.com/chancez/2b97ae9d2b0c225e98ac964e740f27bd