To access the host from inside a Docker container, you can use host.docker.internal as a hostname, at least if you're on a Windows or Mac host.
From the Windows command prompt:
C:\>docker run --rm alpine nslookup host.docker.internal
Server: 192.168.65.1
Address: 192.168.65.1:53
Non-authoritative answer:
Name: host.docker.internal
Address: 192.168.65.2
Server: 192.168.65.1
Address: 192.168.65.1:53
Non-authoritative answer:
Name: host.docker.internal
Address: 192.168.65.2
Final thoughts
Weird how in Linux there's quite a convoluted workaround to do this.