ubuntu 18.04 devstack flat network

stack@zuul:~/devstack$ cat local.conf
[[local|localrc]]
# Define images to be automatically downloaded during the DevStack built process.
DOWNLOAD_DEFAULT_IMAGES=False
IMAGE_URLS="http://download.cirros-cloud.net/0.3.4/cirros-0.3.4-x86_64-disk.img"

# use TryStack git mirror
GIT_BASE=http://git.trystack.cn
NOVNC_REPO=http://git.trystack.cn/kanaka/noVNC.git
SPICE_REPO=http://git.trystack.cn/git/spice/sice-html5.git


# Credentials
DATABASE_PASSWORD=312
ADMIN_PASSWORD=312
MYSQL_PASSWORD=312
SERVICE_PASSWORD=312
SERVICE_TOKEN=312
RABBIT_PASSWORD=312
#FLAT_INTERFACE=enp0s3
HOST_IP=10.0.3.144
SERVICE_IP_VERSION=4

RECLONE=no

# Disable security groups entirely
Q_USE_SECGROUP=False
LIBVIRT_FIREWALL_DRIVER=nova.virt.firewall.NoopFirewallDriver
CINDER_SECURE_DELETE=False

PUBLIC_INTERFACE=ens160
FLOATING_RANGE=10.0.3.0/23
PUBLIC_NETWORK_GATEWAY=10.0.2.1
Q_FLOATING_ALLOCATION_POOL=start=10.0.3.150,end=10.0.3.155