Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Bump to etcd 3.1.12 to pick up critical fix
etcd [3.1.12](https://github.com/coreos/etcd/releases/tag/v3.1.12) (as well as 3.2.17 and 3.3.2) was released yesterday to fix a bug critical to kubernetes:
Fix [mvcc "unsynced" watcher restore operation](https://github.com/coreos/etcd/pull/9297).
- "unsynced" watcher is watcher that needs to be in sync with events that have happened.
- That is, "unsynced" watcher is the slow watcher that was requested on old revision.
- "unsynced" watcher restore operation was not correctly populating its underlying watcher group.
- Which possibly causes [missing events from "unsynced" watchers](https://github.com/coreos/etcd/issues/9086).
This will be backported to 1.9 as well.
Release note:
```release-note
Upgrade the default etcd server version to 3.1.12 to pick up critical etcd "mvcc "unsynced" watcher restore operation" fix.
```
cc @gyuho @wojtek-t @shyamjvs @timothysc @jdumars
This is the 2nd attempt. The previous was reverted while we figured out
the regional mirrors (oops).
New plan: k8s.gcr.io is a read-only facade that auto-detects your source
region (us, eu, or asia for now) and pulls from the closest. To publish
an image, push k8s-staging.gcr.io and it will be synced to the regionals
automatically (similar to today). For now the staging is an alias to
gcr.io/google_containers (the legacy URL).
When we move off of google-owned projects (working on it), then we just
do a one-time sync, and change the google-internal config, and nobody
outside should notice.
We can, in parallel, change the auto-sync into a manual sync - send a PR
to "promote" something from staging, and a bot activates it. Nice and
visible, easy to keep track of.
We shouldn't upgrade etcd without first warning the user that some etcd
version transitions can't be undone. We don't know what version the user
currently has, so we require either an explicit version and image, or an
interactive acknowledgement of this caveat.
This is modeled after the STORAGE_MEDIA_TYPE prompt just above.
RunCmd uses Go's os/exec library to run commands directly. Since these
are not run through a shell, we can't use shell syntax for piping for
file redirection. The proper way to do that is to create a Command
object and set the Std{in,out,err} pipes appropriately. Luckily sed
can handle the behavior we need without having to manually set this up.
Node version cannot be higher than the master version, so we must
switch the node version first. Also, we must use the upgrade script
from the appropriate version for GCE.
