🐛(playbook) avoid downtime during switch or rollback

The current switch_routes  ansible task leave the current  route in an
undefined state  for a few  seconds when switch or  rollback playbooks
are executed.

CHANGELOG.md

@@ -8,6 +8,10 @@ Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Fixed
+
+- Avoid downtime during a switch or rollback
+
 ## [4.6.0] - 2020-01-13
 
 ### Added

tasks/rollback_routes.yml

@@ -10,9 +10,11 @@
   vars:
     prefix_route_src:  "{{ prefix_route.src }}"
     prefix_route_dest: "{{ prefix_route.dest }}"
+    update_src: "{{ prefix_route.update_src | default(True)}}"
   with_items:
     - src:  current
       dest: next
+      update_src: False
     - src:  previous
       dest: current
   loop_control:

tasks/switch_route.yml

@@ -20,3 +20,5 @@
   vars:
     prefix: "{{ prefix_route_src }}"
   tags: switch
+  when: update_src is defined and update_src == True
+

tasks/switch_routes.yml

@@ -10,9 +10,11 @@
   vars:
     prefix_route_src:  "{{ prefix_route.src }}"
     prefix_route_dest: "{{ prefix_route.dest }}"
+    update_src: "{{ prefix_route.update_src | default(True)}}"
   with_items:
     - src:  current
       dest: previous
+      update_src: False
     - src:  next
       dest: current
   loop_control: