Customisation of DNS resolver configuration for website containers

Because Enhance website containers have an isolated network namespace, they are not able to reach localhost on the host operating systemd.  This means that they cannot use systemd-resolved if running on the host o/s.

On container start, Enhance will examine the /etc/resolv.conf on the host o/s.  If it is a symlink or if it contains any local loopback addresses (like 127.0.0.1 or 127.0.0.53), your containers will start with a default /etc/resolv.conf referencing Google and Cloudflare's public resolvers, 8.8.8.8, 8.8.4.4 and 1.1.1.1 .

If you would like to use custom resolvers, ensure that the DNS stub listener in systemd-resolved is disabled on the host o/s which you can set by editing /etc/systemd/resolved.confand restarting the systemd-resolved service.  Make sure the /etc/resolv.conf is not a symlink and contains the resolvers that you wish to set.  Then restart the website/php container for your websites and they will inherit the /etc/resolv.conf from the host o/s with any resolvers that you set in that file.