* Add download_localhost for the download_run_once mode, which is
  use the ansible host (a travis node for CI case) to store and
  distribute containers across cluster nodes in inventory.
  Defaults to false.
* Rework download_run_once logic to fix idempotency of uploading
  containers.
* For Travis CI, enable docker images caching and run Travis
  workers with sudo enabled as a dependency
* For Travis CI, deploy with download_localhost and download_run_once
  enabled to shourten dev path drastically.
* Add compression for saved container images. Defaults to 'best'.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Aleksandr Didenko <adidenko@mirantis.com>

Add one more step (task) to containers download/upload sequence -
copy saved .tar containers to ansible host (delegate_to: localhost).

Then upload images to target nodes. It uses synchronize module so
if ansible host (localhost) is the same host as kube-master[0] then
new task causes no issues and the copy to localhost process is
basically skipped.

Calico CNI binaries are also released/shipped in calico/cni
container. This patch replaces download of calico CNI binaries with
calico/cni container.

Since version 'v1.0.0-beta' calicoctl is written
in Go and its API differs from old Python based
utility. Added support of both old and new version
of the utility.

This patch provides support for Canal network plugin installation
as a self-hosted app, see the following link for details:

https://github.com/tigera/canal/tree/master/k8s-install

* Don't push containers if not changed
* Do preinstall role only once and redistribute defaults to
  corresponding roles

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

Signed-off-by: Chad Swenson <chadswen@gmail.com>

test to change the machine type

Revert "test to change the machine type"

This reverts commit 7a91f1b5405a39bee6cb91940b09a0b0f9d3aee1.

use google dns server when no upstream dns are defined

comment upstream_dns_servers

update documentation

remove deprecated kubelet flags

Revert "remove deprecated kubelet flags"

This reverts commit 21e3b893c896d0291c36a07d0414f4cb88b8d8ac.

and correct checksums

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

Move the variable kube_version to defaults to have the possibility to overwrite it via group_vars inventory if needed.

Save/push/load containers if only download.enabled and download.container

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

"else omit" is causing problems in this expression. Replacing
it with more strict "inventory_hostname" fixes the issue and
handles `download_run_once` as expected.

Closes issue #514

* 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>

Move version/repo vars to download role.
Add container to download params, which overrides url/source_url,
if enabled.
Fix networking plugins download depending on kube_network_plugin.

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

Fixes #450

Nearly the last stage of source all components to containers.
Kubectl will be called from hyperkube image.

Remaining tasks:
 * Move kube_version variable to kubernetes/preinstall
 * Drop placeholder download.nothing requirement

kubelet via docker
kube-apiserver as a static pod

Fixed etcd service start to be more tolerant of slow start.

Workaround for kube_version to stay in download role, but not
download an files by creating a new "nothing" download entry.

Improves upgradability of calicoctl by leveraging docker tags.

This should make things a little more composable,
by making these roles meta roles that perform no
actions by default we allow each role to own its own
resources.

using a shared folder can cause race conditions for the download
role as it tries to download files on all the nodes to the same
shared path.  This adds a flag to run the tasks in the download
role on just one node.