[jjo] add kube-router support (#3339)

* [jjo] add kube-router support

Fixes cloudnativelabs/kube-router#147.

* add kube-router as another network_plugin choice
* support most used kube-router flags via
  `kube_router_foo` vars as other plugins
* implement replacing kube-proxy (--run-service-proxy=true) via
  `kube_proxy_mode: none`, verified in a _non kubeadm_enabled_
  install, should also work for recent kubeadm releases via
  `skipKubeProxyInstall: true` config

* [jjo] address PR#3339 review from @woopstar

* add busybox image used by kube-router to downloads

* fix busybox download groups key

* rework kubeadm_enabled + kube_router_run_service_proxy

- verify it working ok w/the kubeadm_enabled and
  kube_router_run_service_proxy true or false

- introduce `kube_proxy_remove` fact, to decouple logic
  from kube_proxy_mode (which affects kubeadm configmap
  settings, thus no-good to ab-use it to 'none')

* improve kube-router.md re: kubeadm_enabled and kube_router_run_service_proxy

* address @woopstar latest review

* add inventory/sample/group_vars/k8s-cluster/k8s-net-kube-router.yml

* fix kube_router_run_service_proxy conditional for kube-proxy removal

* fix kube_proxy_remove fact (w/ |bool), add some needed kube-proxy tags on my and existing changes

* update kube-router tolerations for 1.12 compatibility

* add PriorityClass to kube-router DaemonSet

roles/network_plugin/kube-router/tasks/main.yml

@@ -0,0 +1,17 @@
+---
+
+- name: kube-router | Copy cni plugins from hyperkube
+  command: "{{ docker_bin_dir }}/docker run --rm -v /opt/cni/bin:/cnibindir {{ hyperkube_image_repo }}:{{ hyperkube_image_tag }} /bin/cp -prf /opt/cni/bin/. /cnibindir/"
+  register: cni_task_result
+  until: cni_task_result.rc == 0
+  retries: 4
+  delay: "{{ retry_stagger | random + 3 }}"
+  changed_when: false
+  tags:
+    - hyperkube
+    - upgrade
+
+- name: kube-router | Create manifest
+  template:
+    src: kube-router.yml.j2
+    dest: "{{ kube_config_dir }}/kube-router.yml"

roles/network_plugin/kube-router/tasks/reset.yml

@@ -0,0 +1,9 @@
+---
+- name: reset | check kube-dummy-if network device
+  stat:
+    path: /sys/class/net/kube-dummy-if
+  register: kube_dummy_if
+
+- name: reset | remove the network device created by kube-router
+  command: ip link del kube-dummy-if
+  when: kube_dummy_if.stat.exists