host_routes using get_attr (Composable Networks)

Uses get_attr on the port resource to resolve attribute
value from neutron subnet 'host_routes' attribute and
pass it to the parameter '{{network.name}}InterfaceRoutes'
in network configuration templates.

A conditional is used in puppet/role.role.j2.yaml. The
user provided parameter value is used whenever it is
not the default: []. This allow advanced user's to
override the routes in neutron.

Co-Authored-By: Dan Sneddon <dsneddon@redhat.com>
Partial: blueprint tripleo-routed-networks-templates
Change-Id: Ie44b211c4aeab9ca79d7994f31961e34aa3517e6

puppet/role.role.j2.yaml

@@ -267,6 +267,16 @@ parameters:
       If not set the nameservers configured in the ctlplane subnet's
       dns_nameservers attribute will be used.
     type: comma_delimited_list
+{%- for network in networks %}
+  {{network.name}}InterfaceRoutes:
+    default: []
+    description: >
+      Routes for the {{network.name_lower}} network traffic.
+      JSON route e.g. [{'destination':'10.0.0.0/16', 'nexthop':'10.0.0.1'}]
+      Unless the default is changed, the parameter is automatically resolved
+      from the subnet host_routes attribute.
+    type: json
+{%- endfor %}
 
   ServerDeletionPolicy:
     description: Whether to retain or delete servers on deletion of the stack
@@ -337,6 +347,11 @@ conditions:
       equals:
         - {get_param: [{{role.name}}IPs, '{{network.name_lower}}', {get_param: NodeIndex}]}
         - ''
+  {{network.name_lower}}_interface_routes_set:
+    not:
+      equals:
+        - {get_param: {{network.name}}InterfaceRoutes}
+        - []
 {%- endfor %}
   ctlplane_subnet_cidr_set:
     not:
@@ -504,6 +519,11 @@ resources:
 
   {%- for network in networks %}
       {{network.name}}IpSubnet: {get_attr: [{{network.name}}Port, ip_subnet]}
+      {{network.name}}InterfaceRoutes:
+        if:
+          - {{network.name_lower}}_interface_routes_set
+          - {get_param: {{network.name}}InterfaceRoutes}
+          - {get_attr: [{{network.name}}Port, host_routes]}
   {%- endfor %}
 
   NetIpMap:

releasenotes/notes/use-attr-interface-routes-dfbe74adce15da1d.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Routes specified in the ``host_routes`` attribute of neutron subnets is
+    passed to ``{{network.name}}InterfaceRoutes`` in network templates. (The
+    routes in neutron subnet's ``host_routes`` can be configured by setting the
+    ``routes`` field in ``network_data.yaml``.)