etcd2 in CoreOS

[Alex Crawford]

We are very excited to announce that etcd2 is now available in CoreOS.
CoreOS 653.0.0, which begins rolling out to the alpha channel today,
features the latest release of this new series, etcd 2.0.8.

Since etcd 0.4 clusters will not automatically migrate to etcd 2.0, we
have decided to ship both `etcd` and `etcd2`. The result is that your
existing clusters will continue to work as before, and you can migrate
to etcd2 at your own pace. We encourage users to use etcd2 for all new
clusters to take advantage of the large number of stability and
performance improvements over the older series.

In order to accommodate two different versions of etcd, listening on
different ports, our tools have been modified to try to connect to both
the old and new endpoints. In this process, we have had to break
backward compatibility in two cases:
1. Starting fleet.service without explicitly starting etcd.service or
etcd2.service will no longer work. If you are using fleet and need
etcd running locally, you will need to also start etcd.service or
etcd2.service.
2. Starting flannel.service without explicitly starting etcd.service or
etcd2.service will no longer work. If you are using flannel and need
etcd running locally, you will need to also start etcd.service or
etcd2.service.

With the release of etcd2, we’ve taken the opportunity to begin the
transition to our IANA-assigned [1] port numbers: 2379 and 2380. For
backward compatibility, etcd2 is configured to listen on both the new
and old port numbers (4001 and 7001) by default, but this can always be
further restricted as desired.

etcd2 can be configured through cloud-config [2] using the new
`coreos.etcd2` section. This works similarly to `coreos.etcd`, but the
options reflect those available in the new etcd. For more information,
check out the coreos-cloudinit docs [3].

Questions? Head over to #coreos or #etcd on Freenode.

[1] http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=etcd
[2] https://coreos.com/docs/cluster-management/setup/cloudinit-cloud-config/
[3] https://github.com/coreos/coreos-cloudinit/blob/v1.4.0/Documentation/cloud-config.md#etcd2

-Alex

[Rimas Mocevicius]

awesome!!!