Liberalize static_route defenition

At the moment a very limited amount of options are supported for
static_routes defenition, which might be a limiting factor in some more
complex solutions.

It is proposed to let operators define `static_routes` with parameters
that are available in systemd-networkd [1] directly, which should
provide required flexbility and not require us additional maintenance
and regular updates of the code.

[1] https://www.freedesktop.org/software/systemd/man/latest/systemd.network.html#%5BRoute%5D%20Section%20Options

Change-Id: I71f81cb497ae8eeb0fab2bc6f9f5eae120d10775

README.md

@@ -64,8 +64,8 @@ Release notes for the project can be found at:
           mtu: 9000
           usedns: true
           static_routes:
-            - gateway: "10.1.0.1"
-              cidr: "10.1.0.0/24"
+            - Gateway: "10.1.0.1"
+              Destination: "10.1.0.0/24"
           config_overrides:
             Network:
               ConfigureWithoutCarrier: true

releasenotes/notes/liberalize_static_routes_defenition-0625db80bcf2e2ed.yaml

@@ -0,0 +1,15 @@
+---
+features:
+  - |
+    Keys for ``static_routes`` were liberalized and now can accept any
+    parameter supported by ``[Route]`` section of systemd-networkd.
+upgrade:
+  - |
+    Following keys for ``static_routes`` list were renamed in order to
+    match with options available in systemd-networkd configuration files:
+
+    - ``cidr`` -> ``Destination``
+    - ``gateway`` -> ``Gateway``
+
+    While backwards compatability was kept, it's highly recommended to
+    use new keys as support for old key names will be removed in the future.

templates/systemd-network-routes.j2

@@ -1,9 +1,18 @@
 # {{ ansible_managed }}
-
 {% for route in item['static_routes'] %}
-[Route]
-Destination={{ route['cidr'] }}
-Gateway={{ route['gateway'] }}
-Metric={{ 20 + loop.index }}
+{%   set route_keys = route.keys() %}
+{%   if 'cidr' in route_keys %}
+{%     set _ = route.update({'Destination': route.pop('cidr')}) %}
+{%   endif %}
+{%   if 'gateway' in route_keys %}
+{%     set _ = route.update({'Gateway': route.pop('gateway')}) %}
+{%   endif %}
 
+[Route]
+{%   for key, value in route.items() %}
+{{ key }}={{ value }}
+{%   endfor %}
+{%   if 'Metric' not in route_keys %}
+Metric={{ 20 + loop.index }}
+{%   endif%}
 {% endfor %}

tests/test.yml

@@ -74,7 +74,7 @@
         mtu: 9000
         usedns: true
         static_routes:
-          - gateway: "10.1.0.1"
+          - Gateway: "10.1.0.1"
             cidr: "10.1.0.0/24"
         config_overrides:
           Network: