Enable HAProxy on single node with multiple interface

[Ettore Simone]

In some edge environment with a single physical node (all-in-one) where is necessary to use a separated interfaces for internal and public OpenStack API access, HAProxy have to bind only to the external interface to proxy to the internal one, without binding to the internal.

The workaround is to enable keepalived with VIPs on both interface, which is not really needed.

A simple solution is to avoid frontend bindings in HAProxy for internal interface id VIP/keepalived is not enable:

              eth0+------eth1
public -----------+ AIO +----------- internal
        10.10.10.1+-----+172.16.0.1

# cat /etc/kolla/globals.yml
---
...
kolla_internal_vip_address: "172.16.0.1"
kolla_external_vip_address: "10.10.10.1"
network_interface: "eth1"
kolla_external_vip_interface: "eth0"
enable_haproxy: "yes"
enable_keepalived: "no"
...

This deployment will stuck in haproxy deployment.

[Ettore Simone (esimone)]

A simple solution could be to add a variable that identify if is present a VIP on the API interface in group_vars/all.yml (e.g. e.g. haproxy_enable_internal_vip: "{{ 'no' if kolla_internal_vip_address == api_interface_address else 'yes' }}") and then put a condition in haproxy_single_service_split.cfg.j2 template to avoid internal front-end and back-end bindings.