Kolla Ansible's bootstrap-servers command provides support for
installing the Docker engine. This is currently done using the packages
at https://apt.dockerproject.org and https://yum.dockerproject.org.
These packages are outdated, with the most recent packages from May 2017
- docker-engine-17.05.

The source for up to date docker packages is
https://download.docker.com, which was introduced with the move to
Docker Community Edition (CE) and Docker Enterprise Edition (EE).

This change adds support to bootstrap-servers for Docker CE for CentOS
and Ubuntu.

It also adds a new variable, 'enable_docker_repo', which controls
whether a package repository for Docker will be enabled.

It also adds a new variable, 'docker_legacy_packages', which controls
whether the legacy packages at dockerproject.org will be used or the
newer packages at docker.com. The default value for this variable is
'false', meaning to use Docker CE.

Upgrading from docker-engine to docker-ce has been tested on CentOS 7.5
and Ubuntu 16.04, by running 'kolla-ansible bootstrap-servers' with
'docker_legacy_packages' set to 'false'. The upgrades were successful,
but result in all containers being stopped. For this reason, the
bootstrap-servers command checks running containers prior to upgrading
packages, and ensures they are running after the package upgrade is
complete.

As mentioned in the release note, care should be taken when upgrading
Docker with clustered services, which could lose quorum. To avoid this,
use --serial or --limit to apply the change in batches.

Change-Id: I6dfd375c868870f8646ef1a8f02c70812e8f6271
Implements: blueprint docker-ce

Prior to this change, when the --limit argument is used, each host in the
limit gathers facts for every other host. This is clearly unnecessary, and
can result in up to (N-1)^2 fact gathers.

This change gathers facts for each host only once. Hosts that are not in
the limit are divided between those that are in the limit, and facts are
gathered via delegation.

This change also factors out the fact gathering logic into a separate
playbook that is imported where necessary.

Change-Id: I923df5af41a7f1b7b0142d0da185a9a0979be543

In change I78cb60168aaa40bb6439198283546b7faf33917c, action was changed
to kolla_action, and serial to kolla_serial, to avoid Ansible warnings
due to use of reserved keywords. In that change, some keywords were
missed, and some changes that were merged since then have not switched
to the new variables. This change fixes all current instances of those
issues.

Change-Id: I357dffdfcb2b405e280a962d366ee65eebf0a8d1
Implements: blueprint migrate-to-ansible-2-2-0

This patchset implements yamllint test to all *.yml
files.

Also fixes syntax errors to make jobs to pass.

Change-Id: I3186adf9835b4d0cada272d156b17d1bc9c2b799

The ansible/kolla-host.yml playbook failed when called with a --limit
flag.

This was due to the fact that only the facts of the subset of hosts
were gathered but the "Generate /etc/hosts for all of the nodes" task
is using the ansible_<IFACE>.ipv4.address variable of all hosts.

The code for this fix is copied from the site.yml playbook
where it was used for the same reason.

Change-Id: I7e70caf750506ad8ab36ec024bd9647dd733fbd0
Closes-Bug: #1713725

Change-Id: I44c2668a8ebb6dd3201a6eb4e47284871380e6d7

Change-Id: Ie70db1b18a73528b1194e4fbcf53d09fed20f4a0
Implements: blueprint kolla-host