August 23, 2025Aug 23 Docker daemon copies /etc/resolv.conf from host into containers on bridge network, which contains an ipv6 address which the container cannot access. (I have enabled IPv6 of course)For example my resolv.conf in a container: (they look the same in all containers)# Generated by Docker Engine. # This file can be edited; Docker Engine will not make further changes once it # has been modified. nameserver 192.168.31.1 nameserver fe80::46df:65ff:fe93:2ab%br0 # Based on host file: '/etc/resolv.conf' (legacy) # Overrides: []The br0 interface doesn't exist in the container, which makes this address unreachable. Which in turn breaks some tools like nslookup.Some version of nslookup reports: nslookup: parse of /etc/resolv.conf failed, and busybox version of nslookup reports: nslookup: bad address 'fe80::46df:65ff:fe93:2ab%br0'. Manual deleting the ipv6 line temporarily fixes the issue, which confirms this is the cause.One of my container depends on nslookup internally, and is broken because of this issue.The container is able to access IPv6 though, other tools like curl is able to resolve and connect to ipv6 websites just fine.
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