Add creating br-ex for compute node in ovn

For ovn compute nodes we need br-ex exactly like with
ComputeDVR role. Now we can do this in jinja templates
using new tag external_bridge

Change-Id: If44e9cbad714ce3954928407c42a8dc2473fed2e
Closes-Bug: #1822367
(cherry picked from commit ff7cce93eb)

network/config/multiple-nics/role.role.j2.yaml

@@ -155,7 +155,8 @@ resources:
                           get_param: {{network.name}}InterfaceDefaultRoute
 {%-             endif %}
 {%-         endif %}
-{%-     elif network.name in role.networks or role.name == 'Networker' or role.name == 'ComputeDVR' %}
+{#- We need bridge also for ComputeDVR and Computes with OVN #}
+{%-     elif network.name in role.networks or 'external_bridge' in role.tags %}
               - type: ovs_bridge
 {%-         if network.name == "External" %}
                 name: bridge_name

releasenotes/notes/create-br-ex-for-compute-b967312323d45d9b.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    Introduce new tag into roles that will create external_bridge (usable only
+    for multiple-nics).
+upgrade:
+  - |
+    During upgrade user will need to create custom roles_data.yaml and remove
+    external_bridge from tags to be sure that bridge will be not added.

roles/Compute.yaml

@@ -5,6 +5,9 @@
   description: |
     Basic Compute Node role
   CountDefault: 1
+  # Create external Neutron bridge (unset if using ML2/OVS without DVR)
+  tags:
+    - external_bridge
   networks:
     InternalApi:
       subnet: internal_api_subnet

roles/ComputeDVR.yaml

@@ -5,6 +5,8 @@
   description: |
     DVR enabled Compute Node role
   CountDefault: 1
+  tags:
+    - external_bridge
   networks:
     InternalApi:
       subnet: internal_api_subnet

roles/Networker.yaml

@@ -9,6 +9,8 @@
       subnet: internal_api_subnet
     Tenant:
       subnet: tenant_subnet
+  tags:
+    - external_bridge
   HostnameFormatDefault: '%stackname%-networker-%index%'
   ServicesDefault:
     - OS::TripleO::Services::Aide

roles/README.rst

@@ -60,6 +60,9 @@ Role Options
   with both 'primary' and 'controller' is used as the primary role for the
   deployment process. If no roles have 'primary' and 'controller', the
   first role in this file is used as the primary role.
+  The third tag that can be defined here is external_bridge, which is used
+  to define which node must have a bridge created in a multiple-nic network
+  config.
 
 * description: (string) as few sentences describing the role and information
   pertaining to the usage of the role.

roles_data.yaml

@@ -196,6 +196,9 @@
   description: |
     Basic Compute Node role
   CountDefault: 1
+  # Create external Neutron bridge (unset if using ML2/OVS without DVR)
+  tags:
+    - external_bridge
   networks:
     InternalApi:
       subnet: internal_api_subnet