FAQ: docker run fails with IPv6 error message

[Christian Heimes]

On Fedora 32 host Docker / moby-engine fails with an IPv6 related error message:

$ docker run ... freeipa-server
systemd v245.6-2.fc32 running in system mode. (+PAM +AUDIT +SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-hierarchy=unified)
Detected virtualization container-other.
Detected architecture x86-64.
Set hostname to <ipa.example.test>.
IPv6 stack is enabled in the kernel but there is no interface that has ::1 address assigned. Add ::1 address resolution to 'lo' interface. You might need to enable IPv6 on the interface 'lo' in sysctl.conf.
The ipa-server-install command failed. See /var/log/ipaserver-install.log for more information
Tue Aug  4 13:25:49 UTC 2020 /usr/sbin/ipa-server-configure-first 

Workaround: https://docs.docker.com/config/daemon/ipv6/

• Edit /etc/docker/daemon.json to enable IPv6 support

{
  "ipv6": true,
  "fixed-cidr-v6": "2001:db8:1::/64"
}

• systemctl restart docker

[Jan Pazdziora]

Alternatively, docker run --sysctl net.ipv6.conf.all.disable_ipv6=0 ... does the trick as well.