Make Docker containers listen on `[::]` (IPv6)

README.md

Add the following to /etc/docker/daemon.json:

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

Now systemctl restart docker. Validate with ss -tlnp:

# ss -tlnp
State                                     Recv-Q                                    Send-Q                                                                         Local Address:Port                                                                         Peer Address:Port                                                                                                               
LISTEN                                    0                                         128                                                                                  0.0.0.0:22                                                                                0.0.0.0:*                                        users:(("sshd",pid=484,fd=3))                                             
LISTEN                                    0                                         5                                                                                  127.0.0.1:631                                                                               0.0.0.0:*                                        users:(("cupsd",pid=472,fd=7))                                            
LISTEN                                    0                                         128                                                                                  0.0.0.0:7000                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5125,fd=4))                                    
LISTEN                                    0                                         128                                                                                  0.0.0.0:7001                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5105,fd=4))                                    
LISTEN                                    0                                         128                                                                                  0.0.0.0:7002                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5087,fd=4))                                    
LISTEN                                    0                                         128                                                                                  0.0.0.0:7003                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5067,fd=4))                                    
LISTEN                                    0                                         128                                                                                  0.0.0.0:7004                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5048,fd=4))                                    
LISTEN                                    0                                         128                                                                                  0.0.0.0:7005                                                                              0.0.0.0:*                                        users:(("docker-proxy",pid=5027,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:22                                                                                   [::]:*                                        users:(("sshd",pid=484,fd=4))                                             
LISTEN                                    0                                         5                                                                                      [::1]:631                                                                                  [::]:*                                        users:(("cupsd",pid=472,fd=6))                                            
LISTEN                                    0                                         128                                                                                     [::]:7000                                                                                 [::]:*                                        users:(("docker-proxy",pid=5131,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:7001                                                                                 [::]:*                                        users:(("docker-proxy",pid=5113,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:7002                                                                                 [::]:*                                        users:(("docker-proxy",pid=5093,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:7003                                                                                 [::]:*                                        users:(("docker-proxy",pid=5072,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:7004                                                                                 [::]:*                                        users:(("docker-proxy",pid=5055,fd=4))                                    
LISTEN                                    0                                         128                                                                                     [::]:7005                                                                                 [::]:*                                        users:(("docker-proxy",pid=5033,fd=4))