[Unit]
Description=Run openvswitch-initialize-db (once)
After=local-fs.target openvswitch-db-server.service

ConditionPathExists=!/usr/local/var/run/openvswitch/openvswitch-initialize-db-flag

[Service]
Type=oneshot
ExecStart=/usr/bin/ovs-vsctl --no-wait init
ExecStart=/bin/touch /usr/local/var/run/openvswitch/openvswitch-initialize-db-flag