Description of problem:
This is a long standing issue and present in both OSP 10 and OSP 13: https://access.redhat.com/solutions/3445231

When switching from NeutronTunnelTypes: 'vxlan' to NeutronTunnelTypes: '' in a cloud that was already deployed, puppet does not unset `agent/tunnel_types`, but it does unset `ovs_local_ip`. This leads to the following ERROR:
~~~
ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent [-] Tunneling can't be enabled with invalid local_ip 'None'. IP couldn't be found on this host's interfaces.
~~~

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.
2.
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Actual results:


Expected results:


Additional info:

NeutronTunnelTypes: '' sets the following hieradata:
~~~
/etc/puppet/hieradata/service_configs.yaml:neutron::agents::ml2::ovs::tunnel_types: []
~~~

Which updates local_ip to the default of <None>:
~~~
/etc/neutron/plugins/ml2/openvswitch_agent.ini:#local_ip = <None>
~~~

However, Director keeps the definition for tunnel_types as "vxlan":
~~~
/etc/neutron/plugins/ml2/openvswitch_agent.ini:tunnel_types =vxlan
~~~

This looks like a bug, in /etc/puppet/modules/neutron/manifests/agents/ml2/ovs.pp:
~~~
  if $enable_tunneling_real {
    neutron_agent_ovs {
      'ovs/tunnel_bridge':         value => $tunnel_bridge;
      'ovs/local_ip':              value => $local_ip;
      'ovs/int_peer_patch_port':   value => $int_peer_patch_port;
      'ovs/tun_peer_patch_port':   value => $tun_peer_patch_port;
      'agent/tunnel_types':        value => join($tunnel_types, ',');
    }

    if 'vxlan' in $tunnel_types {
      validate_vxlan_udp_port($vxlan_udp_port)
      neutron_agent_ovs {
        'agent/vxlan_udp_port': value => $vxlan_udp_port;
      }
    }
  } else {
    neutron_agent_ovs {
      'ovs/tunnel_bridge':         ensure => absent;
      'ovs/local_ip':              ensure => absent;
      'ovs/int_peer_patch_port':   ensure => absent;
      'ovs/tun_peer_patch_port':   ensure => absent;
    }
  }
~~~

Looking at the  `else` section, agent/tunnel_types should be set to "ensure => absent". The same issue still exists in OSP 13.