Getting Public IP while using lxdbr0 (NAT)

I use Caddy to forward HTTP/HTTPS traffic to containers. I also use Gobetween to stream TCP/UDP ports to containers.

For both of Caddy & Gobetween I always get the lxdbr0 IP address to logs as Public IP.

What’s the proper way to get Public IP for containers’ applications: Apache HTTP, Nginx, Caddy, OpenVPN etc.

And I also tried to run iptables for NAT. But cannot see the NAT at iptables rules list:

[23:21:39@9] [root@lxd:~]# iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 587 -j DNAT --to-destination 100.66.2.161:80
[23:25:26@9] [root@lxd:~]# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:domain /* generated for LXD network lxdbr0 */
ACCEPT     udp  --  anywhere             anywhere             udp dpt:domain /* generated for LXD network lxdbr0 */
ACCEPT     udp  --  anywhere             anywhere             udp dpt:bootps /* generated for LXD network lxdbr0 */

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere             /* generated for LXD network lxdbr0 */
ACCEPT     all  --  anywhere             anywhere             /* generated for LXD network lxdbr0 */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             tcp spt:domain /* generated for LXD network lxdbr0 */
ACCEPT     udp  --  anywhere             anywhere             udp spt:domain /* generated for LXD network lxdbr0 */
ACCEPT     udp  --  anywhere             anywhere             udp spt:bootps /* generated for LXD network lxdbr0 */

Caddyfile:

subdomain.example.com {
        proxy / rubyonrails.lxd:9292 {
                transparent
        }
        gzip
}

Gobetween:

[servers.rubyonrails]
protocol = "tcp"
bind = "0.0.0.0:9292"

  [servers.rubyonrails.discovery]
  kind = "static"
  static_list = [
      "rubyonrails.lxd:9292"
  ]

LXD version: 2.17
OS: Ubuntu 16.04
eth0: 10.5.138.205
lxdbr0: 100.66.2.1