Containerized deployment docs not working

[Ben Nemec]

The very first step, discovering the tag, seems to be broken:

(undercloud) [centos@undercloud-upstream ~]$ openstack overcloud container image tag discover --image trunk.registry.rdoproject.org/master/centos-binary-base:current-tripleo-rdo --tag-from-label rdo_version
docker pull failed: Error: image master/centos-binary-base:3b85715c6488a692fcdf4e4c6a589d77c60eb5a6_a3792c8d not found
retrying pulling image: trunk.registry.rdoproject.org/master/centos-binary-base:3b85715c6488a692fcdf4e4c6a589d77c60eb5a6_a3792c8d
docker pull failed: Error: image master/centos-binary-base:3b85715c6488a692fcdf4e4c6a589d77c60eb5a6_a3792c8d not found
<retries until failure>

mhenkel provided an alternate command which at least resulted in a valid id: python -c 'import urllib2;import yaml;c=yaml.load(urllib2.urlopen("https://trunk.rdoproject.org/centos7-master/current-tripleo/commit.yaml"))["commits"][0];print "%s_%s" % (c["commit_hash"],c["distro_hash"][0:8])'

Seems like we need to fix something in the tag discover command.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/542365

[OpenStack Infra (hudson-openstack)]

Change abandoned by Jill Rouleau (<email address hidden>) on branch: master
Review: https://review.openstack.org/542365
Reason: Turns out this will already be addressed by wip https://review.openstack.org/#/c/541962

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/541962
Committed: https://git.openstack.org/cgit/openstack/tripleo-docs/commit/?id=f622a160f4270536c0ecd4ec11f446f5b85f86e0
Submitter: Zuul
Branch: master

commit f622a160f4270536c0ecd4ec11f446f5b85f86e0
Author: Steve Baker <email address hidden>
Date: Thu Feb 8 13:52:50 2018 +1300

    Simplify container prepare instructions

    Now that the prepare command supports --tag-from-label discovery on
    every image, the separate discover command is no longer required.

    This change also switches the image namespace to
    docker.io/tripleomaster. trunk.registry.rdoproject.org was never
    intended to be used for deploying openstack from since it is a piece
    of infrastructre used in the RDO image build pipeline.
    docker.io/tripleomaster is more appropriate since it contains the
    tested images which are also hosted on trunk.registry.rdoproject.org.

    Change-Id: I4fd54d4374bde9120aa2c74725bfd2db4b3cf3d0
    Closes-Bug: #1741544