Missing corresponding package docker-engine on aarch64, use docker instead.

Change-Id: If5df58337746a81752b5d477e0473600eaee8381

This reverts commit 51f4e658.

If the 'docker' package is already installed, then the handlers will not
run and the service will not be (re-)started. As such, lets make sure
that the service is started even if the packages are already installed.

Add support for installing Docker on SUSE distributions. The Docker
repository at https://yum.dockerproject.org/repo/main/ does not support
recent openSUSE distributions so the only alternative is to use the
packages from the distro repositories. This however renders the
'docker_version' Ansible variable useless on SUSE.

* Remove old docker packages

This removes docker packages that are obsolete if docker-ce packages are to be installed, which fixes some package conflict issues that can occur during upgrades.

* Add support for setting obsoletes=0 when installing docker with yum

Support docker-ce and docker-engine include redhat/centos ubuntu debian

import_tasks will consume far less memory, so it should be
used whenever it is compatible.

Renaming runtime docker_version to prevent setting that
value on the command line from breaking the play run.

This fixes #2081

This allows overriding of apt repo endpoints when internet sources are not accessible. Additionally, switch to using the dockerproject.org gpg key url for apt instead of keyservers.net

* Set no_proxy to all local ips

* Use proxy settings on all necessary tasks

* Adding yaml linter to ci check

* Minor linting fixes from yamllint

* Changing CI to install python pkgs from requirements.txt

- adding in a secondary requirements.txt for tests
- moving yamllint to tests requirements

Updates based on feedback

Simplify checks for file exists

remove invalid char

Review feedback. Use regular systemd file.

Add template for docker systemd atomic

Using the command module instead of raw.
Also fixed the syntax.

Docker upgrade doesn't auto-restart docker, causing failures
when trying to start another container

Also update reset.yml to do more dns/network related cleanup.

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Add tags to allow more granular tasks filtering.
Add generator script for MD formatted tags found.
Add docs for tags how-to.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

* Add the retry_stagger var to tweak push and retry time strategies.
* Add large deployments related docs.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Creating the unit using default settings early on
and then changing it during network_plugin section
leads to too many docker restarts and duplicated code.

Reversed Wants= dependence on docker.service so it does not
restart docker when reloading systemd

Consolidated all docker restart handlers.

This allows Ubuntu/Debian to downgrade Docker version if
a newer version is installed, instead of failing.