more

config.yaml

@@ -169,6 +169,12 @@ options:
       To improve network performance of VM, sometimes we should keep VM MTU as
       1500 and use charm to modify MTU of tunnel nic more than 1500 (e.g. 1546
       for GRE). A value of zero means no mtu will be set/modified.
+  network-device-mtu:
+    type: int
+    default: 0
+    description: |
+      The MTU size for the interfaces managed by neutron. If set to 0, no value
+      will be applied.
   # Storage configuration options
   libvirt-image-backend:
     default:

hooks/nova_compute_context.py

@@ -338,6 +338,10 @@ class CloudComputeContext(context.OSContextGenerator):
             ctxt['network_manager'] = self.network_manager
             ctxt['network_manager_config'] = net_manager
 
+        net_dev_mtu = config('network-device-mtu')
+        if net_dev_mtu:
+            ctxt['network_device_mtu'] = net_dev_mtu
+
         vol_service = self.volume_context()
         if vol_service:
             ctxt['volume_service'] = vol_service

templates/havana/nova.conf

@@ -76,6 +76,10 @@ network_api_class = nova.network.neutronv2.api.API
 network_manager = nova.network.manager.FlatDHCPManager
 {% endif -%}
 
+{% if network_device_mtu -%}
+network_device_mtu = {{ network_device_mtu }}
+{% endif -%}
+
 {% if volume_service -%}
 volume_api_class = nova.volume.cinder.API
 {% endif -%}