Unable to resolve hostnames inside macOS chroot jail
I was able to get it to work by making sure the /etc/resolver.conf existed in the chroot and then symlinking /var/run/mDNSResponder into the chroot.

$ sudo chroot -u user "/Users/user/Source/macos-mkjail/test_jail" /bin/bash
bash-4.4$ ping www.google.com
PING www.google.com (216.58.194.164): 56 data bytes
64 bytes from 216.58.194.164: icmp_seq=0 ttl=53 time=10326.366 ms
64 bytes from 216.58.194.164: icmp_seq=1 ttl=53 time=44.899 ms
64 bytes from 216.58.194.164: icmp_seq=2 ttl=53 time=39.388 ms
^C--- www.google.com ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 39.388/3470.218/10326.366/4848.030 ms
bash-4.4$exit
$