Add Availability Zone variables

At the moment the only way to configure multi-AZ support in Neutron were
config overrides, which work quite nicely with LXB/OVS scenarios. However,
with OVN changing configuration is not enough, and command that sets
up OVN Gateway should provide extra CMS option.

In order to improve AZ support in Neutron role, we add couple of variables
that control behaviour and allow to perform required configuration without
config overrides for OVS/LXB/OVN.

Co-Authored-By: Danila Balagansky <dbalagansky@me.com>
Closes-Bug: #2002040
Change-Id: Ic964329c06765176692f7b0c32f33ec46360a3fb

defaults/main.yml

@@ -334,6 +334,18 @@ neutron_keystone_auth_plugin: "{{ neutron_keystone_auth_type }}"
 neutron_keystone_auth_type: password
 neutron_service_in_ldap: "{{ service_ldap_backend_enabled | default(False) }}"
 
+###
+### Availability zones
+###
+# Default availability zones do define a list of zones to where routers/agents
+# will be scheduled by default. This is a list, since a deployment might stretch
+# networks across AZs
+neutron_default_availability_zones: []
+
+# Availability zone defines current AZ of the component. For OVN you can define
+# multiple AZs separated with a colon, ie "az1:az2"
+neutron_availability_zone: nova
+
 ###
 ### Telemetry integration
 ###

releasenotes/notes/neutron_az_support-97f3ab40bf554766.yaml

@@ -0,0 +1,12 @@
+---
+features:
+  - |
+    Added extra variables to Neutron role for Availability Zones configuration:
+
+      * ``neutron_default_availability_zones`` - defines a list of AZs where
+        l3/dhcp agents or OVN routers/ports will be scheduled to when hint is
+        not provided in a request to Neutron API.
+      * ``neutron_availability_zone`` - Availability Zone of the current
+        component. It is recommended to leverage group/host_vars for setting
+        this variable.
+        For OVN this variable can contain multiple values spearated by colon.

tasks/providers/setup_ovs_ovn.yml

@@ -22,7 +22,7 @@
 
 - name: Set CMS Options for Gateway Scheduling
   changed_when: false
-  command: "ovs-vsctl set open . external-ids:ovn-cms-options=enable-chassis-as-gw"
+  command: "ovs-vsctl set Open_vSwitch . external-ids:ovn-cms-options=enable-chassis-as-gw,availability-zones={{ neutron_availability_zone }}"
   when:
     - '"neutron_ovn_gateway" in group_names'
 

templates/dhcp_agent.ini.j2

@@ -18,3 +18,6 @@ dnsmasq_lease_max = {{ neutron_dnsmasq_lease_max }}
 # Metadata
 enable_isolated_metadata = True
 force_metadata = {{ neutron_dnsmasq_force_metadata }}
+
+[AGENT]
+availability_zone = {{ neutron_availability_zone }}

templates/l3_agent.ini.j2

@@ -47,7 +47,8 @@ vpn_device_driver = {{ neutron_driver_vpnaas }}
 {% set _ = l3_agent_plugins.append("port_forwarding") %}
 {% endif %}
 
-{% if l3_agent_plugins|length > 0 %}
 [AGENT]
+{% if l3_agent_plugins | length > 0 %}
 extensions = {{ l3_agent_plugins | join(',') }}
 {% endif %}
+availability_zone = {{ neutron_availability_zone }}

templates/neutron.conf.j2

@@ -31,6 +31,15 @@ use_ssl = {{ neutron_backend_ssl }}
 # General, only applies to neutron server host group
 vlan_transparent = False
 
+# Availability zone
+{% if neutron_default_availability_zones %}
+default_availability_zones = {{ neutron_default_availability_zones | join(',') }}
+{%   if neutron_default_availability_zones | length > 1 %}
+router_scheduler_driver = neutron.scheduler.l3_agent_scheduler.AZLeastRoutersScheduler
+network_scheduler_driver = neutron.scheduler.dhcp_agent_scheduler.AZAwareWeightScheduler
+{%   endif %}
+{% endif %}
+
 # Plugins
 core_plugin = {{ neutron_plugin_core }}
 {% if neutron_plugin_type.split('.')[0] == 'ml2' %}