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.
Stop supporting the "nsenter" exec handler. Only the Docker native exec
handler is supported.
The flag was deprecated in Kubernetes 1.6 and is safe to remove
in Kubernetes 1.9 according to the deprecation policy.
A shared PID namespace were enabled by default in the 1.7 when running
with a supported Docker runtime, but a Docker version that supports
a shared namespace was not qualified for use.
Release 1.8 will qualify a docker version supporting shared PID, but we
don't want to cause disruption for container images which expect always
to have PID 1.
