failed to create kuma k3d cluster for local with Makefile command

[Icarus9913]

What happened?

I followed the DEVELOPER.md to run the kuma k3d cluster but met a failure.

command: make -j k3d/restart

Error from server (parsing address pool main: invalid CIDR "fd00:fd12:3456::0/64..3.0/24" in pool "main": invalid CIDR "fd00:fd12:3456::0/64..3.0/24"): error when creating "STDIN": admission webhook "ipaddresspoolvalidationwebhook.metallb.io" denied the request: parsing address pool main: invalid CIDR "fd00:fd12:3456::0/64..3.0/24" in pool "main": invalid CIDR "fd00:fd12:3456::0/64..3.0/24"
make[2]: *** [k3d/configure/metallb] Error 1
make[1]: *** [k3d/start] Error 2
make: *** [k3d/restart] Error 2

Then I found the command docker network inspect kind --format '{{ (index .IPAM.Config 0).Subnet }}') will select the IPv6 address fd00:fd12:3456::0/64, which leads to the failure.

icarus.wu@konghq.com@Icarus ~ %docker network inspect kind
[
    {
        ......
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "fd00:fd12:3456::0/64"
                },
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },

[Icarus9913]

Actually, I did meet this problem in the past with the new version docker.
And I did the following command to fix it with spiderpool project, but looks like a little bit cumbersome.

ipv4_regex="^([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]+)$$"; \
ipv6_regex="^([a-fA-F0-9:]+\/[0-9]+)$$"; \
subnet0=$$(docker network inspect kind -f {{\(index\ $$.IPAM.Config\ 0\).Subnet}}) ; \
gateway0=$$(docker network inspect kind -f {{\(index\ $$.IPAM.Config\ 0\).Gateway}}) ; \
subnet1=$$(docker network inspect kind -f {{\(index\ $$.IPAM.Config\ 1\).Subnet}}) ; \
gateway1=$$(docker network inspect kind -f {{\(index\ $$.IPAM.Config\ 1\).Gateway}}) ; \
if [[ $${subnet0} =~ $${ipv4_regex} ]]; then \
	ipv4_subnet=$${subnet0}; \
	ipv4_gateway=$${gateway0}; \
elif [[ $${subnet0} =~ $${ipv6_regex} ]]; then \
	ipv6_subnet=$${subnet0}; \
	ipv6_gateway=$${gateway0}; \
fi; \
if [[ $${subnet1} =~ $${ipv4_regex} ]]; then \
	ipv4_subnet=$${subnet1}; \
	ipv4_gateway=$${gateway1}; \
elif [[ $${subnet1} =~ $${ipv6_regex} ]]; then \
	ipv6_subnet=$${subnet1}; \
	ipv6_gateway=$${gateway1}; \
fi;  \
echo "docker network kind IPv4 subnet $${ipv4_subnet}"; \
echo "docker network kind IPv4 gateway $${ipv4_gateway}"; \
echo "docker network kind IPv6 subnet $${ipv6_subnet}"; \
echo "docker network kind IPv6 gateway $${ipv6_gateway}"; \

[Icarus9913]

What's more, the index .IPAM.Config property is an array and how could we get its length in order to avoid the out of length error occurs.