I have a composition with the default networking configuration and a definition such as:
services:
myservice:
image: someimage
restart: always
ports:
- 80:80
- 443:443
The service properly binds to IPv4 and can be accessed as expected. Since a week or two, the service does no longer bind to IPv6 which previously worked without problems. Running netstat -plnt shows me that the docker-proxy is not listening on IPv6 ports:
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:6379 0.0.0.0:* LISTEN 1936/docker-proxy
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1898/docker-proxy
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 811/systemd-resolve
tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 1883/docker-proxy
tcp6 0 0 :::2377 :::* LISTEN 1283/dockerd
tcp6 0 0 :::7946 :::* LISTEN 1283/dockerd
So you can see that ports 80 and 443 are exposed on tcp but not tcp6. Searching for this issue I can only find the reversed problem (docker is listening on IPv6 but not IPv4).
When trying to bin the port with socat the port is reported in use (while netstat states it is not). Binding port 81 to the IPv4 address on port 80 allows me to access the server via IPv6 so there is no routing issue anywhere else.
sudo socat TCP6-LISTEN:80,fork TCP4:127.0.0.1:80
2021/01/13 16:08:50 socat[26572] E bind(5, {AF=10 [0000:0000:0000:0000:0000:0000:0000:0000]:80}, 28): Address already in use
docker inspect shows the following information:
"NetworkSettings": {
"Bridge": "",
"SandboxID": "d5fdebb4de954a4d7c1800490e44d0f53c4ee827775edb8ba286583e888eaa07",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {
"443/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "443"
}
],
"80/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "80"
}
]
},
"SandboxKey": "/var/run/docker/netns/d5fdebb4de95",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "",
"Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "",
"IPPrefixLen": 0,
"IPv6Gateway": "",
"MacAddress": "",
"Networks": {
"docker_default": {
"IPAMConfig": null,
"Links": null,
"Aliases": [
"d8acfbf724cf"
],
"NetworkID": "87b6b52c779252614553040f217f9f2310ee3cce5f1a450f6a8210e8ea411b5a",
"EndpointID": "a6bdf4d85641a043c25812ac0759a7ad872a3ee15ff7ea0e3ddf6b2405967737",
"Gateway": "172.20.0.1",
"IPAddress": "172.20.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:14:00:02",
"DriverOpts": null
}
}
}
