Add param to configure snat mechanism

Add a parameter to configure SNAT mechanism in OpenDayLight defaulting
to conntrack for OVS and defaulting to controller mechanism for OVS-DPDK

Change-Id: I48c6f07de55cb2574cc3a7e9653b812f875df726
Closes-Bug: #1710614

environments/neutron-opendaylight-dpdk.yaml

@@ -12,6 +12,7 @@ parameter_defaults:
   NeutronMechanismDrivers: 'opendaylight_v2'
   NeutronServicePlugins: 'odl-router_v2'
   NovaSchedulerDefaultFilters: "RamFilter,ComputeFilter,AvailabilityZoneFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter,NUMATopologyFilter"
+  OpenDaylightSNATMechanism: 'controller'
 
   ComputeOvsDpdkParameters:
     OvsEnableDpdk: True

puppet/services/opendaylight-api.yaml

@@ -62,6 +62,14 @@ parameters:
     description: Whether to manage the OpenDaylight repository
     type: boolean
     default: false
+  OpenDaylightSNATMechanism:
+    description: SNAT mechanism to be used
+    default: 'conntrack'
+    type: string
+    constraints:
+      - allowed_values:
+          - conntrack
+          - controller
 
 outputs:
   role_data:
@@ -84,6 +92,7 @@ outputs:
                   - 6640
                   - 6653
                   - 2550
+        opendaylight::snat_mechanism: {get_param: OpenDaylightSNATMechanism}
       step_config: |
         include tripleo::profile::base::neutron::opendaylight
       upgrade_tasks:

releasenotes/notes/configuring-snat-in-opendaylight-d5ed4d62275e1876.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Configure OpenDaylight SNAT to use conntrack mechanism with OVS and controller
+    based mechanism with OVS-DPDK.