Change "command" to "shell" in order for the pipe to work correctly

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

The search line in /etc/resolv.conf could have
multiple spaces or tabs between domains.
split(' ') will give wrong results in some case,
use split() without argument instead.

e.g.
>>> 'domain.tld	cluster.tld '.split(' ')
['domain.tld\tcluster.tld', '']
>>> 'domain.tld cluster.tld '.split()
['domain.tld', 'cluster.tld']

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

* don't try to install this rpm on fedora atomic

* add docker 1.13.1 for fedora

* built-in docker unit file is sufficient, as tested on both fedora and centos atomic

* Rename dns_server to dnsmasq_dns_server so that it includes role prefix
as the var name is generic and conflicts when integrating with existing ansible automation.
*  Enable selinux state to be configurable with new var preinstall_selinux_state

* 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

* Make yum repos used for installing docker rpms configurable
* TasksMax is only supported in systemd version >= 226
* Change to systemd file should restart docker

Updates based on feedback

Simplify checks for file exists

remove invalid char

Review feedback. Use regular systemd file.

Add template for docker systemd atomic

Migrate older inline= syntax to pure yml syntax for module args as to be consistant with most of the rest of the tasks
Cleanup some spacing in various files
Rename some files named yaml to yml for consistancy

"shell" step doesn't support check mode, which currently leads to failures,
when Ansible is being run in check mode (because Ansible doesn't run command,
assuming that command might have effect, and no "rc" or "output" is registered).

Setting "check_mode: no" allows to run those "shell" commands in check mode
(which is safe, because those shell commands doesn't have side effects).

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

Fixes scenario where docker-dns.conf tries to create an empty
search entry

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.