OVN: Add ovn_emit_need_to_frag configuration option

This patch is adding a new configuration option called
"ovn_emit_need_to_frag" to be set in the "ovn" section of
etc/neutron/plugins/ml2_conf.ini.

When set to True the option tells ovn whether it should emit "need to
frag" packets in case of MTU mismatch. Before enabling this configuration
make sure that its supported by the host kernel (version >= 5.2) or by
checking the output of the following command: ovs-appctl -t ovs-vswitchd
dpif/show-dp-features br-int | grep "Check pkt length action". Defaults
to False.

This option was intruced by networking-ovn at:
https://review.opendev.org/#/c/671766/

Change-Id: I258402e8033726aa9abf2dc5f801fdf724ab9e3a
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>

manifests/plugins/ml2/ovn.pp

@@ -91,6 +91,16 @@
 #   (optional) The vhost-user socket directory for OVS
 #   Type: String
 #   Defaults to $::os_service_default
+#
+# [*ovn_emit_need_to_frag*]
+#   (optional) Configure OVN to emit "need to frag" packets in case
+#              of MTU mismatch. Before enabling this configuration make
+#              sure that its supported by the host kernel (version >=
+#              5.2) or by checking the output of the following command:
+#              ovs-appctl -t ovs-vswitchd dpif/show-dp-features br-int |
+#              grep "Check pkt length action".
+#   Type: boolean
+#   Defaults to $::os_service_default
 
 class neutron::plugins::ml2::ovn(
   $ovn_nb_connection        = $::os_service_default,
@@ -110,6 +120,7 @@ class neutron::plugins::ml2::ovn(
   $dvr_enabled              = $::os_service_default,
   $dns_servers              = $::os_service_default,
   $vhostuser_socket_dir     = $::os_service_default,
+  $ovn_emit_need_to_frag    = $::os_service_default,
   ) {
 
   include ::neutron::deps
@@ -151,5 +162,6 @@ class neutron::plugins::ml2::ovn(
     'ovn/enable_distributed_floating_ip' : value => $dvr_enabled;
     'ovn/dns_servers'              : value => join(any2array($dns_servers), ',');
     'ovn/vhost_sock_dir'           : value => $vhostuser_socket_dir;
+    'ovn/ovn_emit_need_to_frag'    : value => $ovn_emit_need_to_frag;
   }
 }

releasenotes/notes/ovn-emit-need-to-frag-config-option-89c716cd33592bea.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    Add a new configuration option called "ovn_emit_need_to_frag" to
+    the "ovn" section of etc/neutron/plugins/ml2_conf.ini. This new
+    option tells ovn whether it should emit "need to frag" packets
+    in case of MTU mismatch. Before enabling this configuration make
+    sure that its supported by the host kernel (version >= 5.2) or
+    by checking the output of the following command: ovs-appctl -t
+    ovs-vswitchd dpif/show-dp-features br-int | grep "Check pkt length
+    action". Defaults to False.

spec/classes/neutron_plugins_ml2_ovn_spec.rb

@@ -25,6 +25,7 @@ describe 'neutron::plugins::ml2::ovn' do
        :vif_type                 => 'ovs',
        :dvr_enabled              => false,
        :dns_servers              => ['8.8.8.8', '10.10.10.10'],
+       :ovn_emit_need_to_frag    => false,
     }
   end
 
@@ -54,6 +55,7 @@ describe 'neutron::plugins::ml2::ovn' do
       should contain_neutron_plugin_ml2('ovn/enable_distributed_floating_ip').with_value(params[:dvr_enabled])
       should contain_neutron_plugin_ml2('ovn/dns_servers').with_value(params[:dns_servers].join(','))
       should contain_neutron_plugin_ml2('ovn/vhost_sock_dir').with_value('<SERVICE DEFAULT>')
+      should contain_neutron_plugin_ml2('ovn/ovn_emit_need_to_frag').with_value(params[:ovn_emit_need_to_frag])
     end
 
   end
@@ -93,6 +95,15 @@ describe 'neutron::plugins::ml2::ovn' do
         should contain_neutron_plugin_ml2('ovn/enable_distributed_floating_ip').with_value(params[:dvr_enabled])
       end
     end
+
+    context 'with emit need to fragment enabled' do
+      before :each do
+        params.merge!(:ovn_emit_need_to_frag => true)
+      end
+      it 'should enable emit need to fragment option' do
+        should contain_neutron_plugin_ml2('ovn/ovn_emit_need_to_frag').with_value(params[:ovn_emit_need_to_frag])
+      end
+    end
   end
 
   on_supported_os({