Allow setting physical network MTU via heat template

Add 'neutron::plugins::ml2::physical_network_mtus' as a
NeutronML2PhysicalNetworkMtus in heat template to allow
set MTU in ml2 plugin

Change-Id: I2f9666a5422a1272d53c869e4dad8581ab605b37
Closes-Bug: 1782123

puppet/services/neutron-plugin-ml2.yaml

@@ -82,6 +82,19 @@ parameters:
     type: number
     constraints:
     - allowed_values: [4,6]
+  NeutronML2PhysicalNetworkMtus:
+    default: []
+    description: |
+        A list of mappings of physical networks to MTU values. The format of
+        the mapping is <physnet>:<mtu val>. This mapping allows specifying a
+        physical network MTU value that differs from the default segment_mtu
+        value in ML2 plugin. And overwrite values from global_physnet_mtu for
+        selected network.
+    type: comma_delimited_list
+
+conditions:
+  physical_network_mtus_set: {not: {equals: [{get_param: NeutronML2PhysicalNetworkMtus}, []]}}
+
 resources:
 
   NeutronBase:
@@ -112,6 +125,10 @@ outputs:
             neutron::plugins::ml2::tenant_network_types: {get_param: NeutronNetworkType}
             neutron::plugins::ml2::firewall_driver: {get_param: NeutronFirewallDriver}
             neutron::plugins::ml2::overlay_ip_version: {get_param: NeutronOverlayIPVersion}
+          - if:
+            - physical_network_mtus_set
+            - neutron::plugins::ml2::physical_network_mtus: {get_param: NeutronML2PhysicalNetworkMtus}
+            - null
 
       step_config: |
         include ::tripleo::profile::base::neutron::plugins::ml2

releasenotes/notes/bug-1782123-7b08ab6503033dd3.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Add 'neutron::plugins::ml2::physical_network_mtus' as a
+    NeutronML2PhysicalNetworkMtus in heat template to allow
+    set MTU in ml2 plugin