Using docker v6, what's the format for environment variables relating to the options described at Interfaces - Pi-hole documentation ?
e.g to use the dnsmasq option 'interface', I've tried:
FTLCONF_dns_dnsmasq_interface
FTLCONF_dnsmasq_interface
FTLCONF_dns_interface
FTLCONF_interface
but none of those works.
Never mind. I've found them sitting in pihole.toml
With Docker, you should use environment variables to configure your Pi-hole container (so you were on the right track 
).
It seems you were trying to configure your Pi-hole container for a specific network interface.
That can be achieved by setting the INTERFACE advanced environment variable:
Variable Default Value Description INTERFACE unset The default works fine with our basic example docker run commands. If you're trying to use DHCP with --net host mode then you may have to customize this or DNSMASQ_LISTENING.
Just to avoid confusion... For the V6 docker container, the relevant Readme should be consulted, where one will note that the INTERFACE environment variable no longer exists 
https://github.com/pi-hole/docker-pi-hole/tree/development-v6
Yeah, I found the relevant settings in pihole.yaml
Thanks anyway!
