Disable IPV6 support

[dimm0]

Describe the problem to be solved

In dual-stack cluster where only part of nodes support IPV6, spell sometimes can get the master (lease) with V6 address, which will make V4 only nodes not able to use spegel

Proposed solution to the problem

Add an option to disable V6 or disable the master V6

[phillebaba]

I never considered this when implementing the original support for ipv6. Looking at the current logic it is pretty obvious that this is an issue.

spegel/pkg/routing/p2p.go

Lines 49 to 68 in 80dabcb

	addrFactoryOpt := libp2p.AddrsFactory(func(addrs []ma.Multiaddr) []ma.Multiaddr {
	var ip4Ma, ip6Ma ma.Multiaddr
	for _, addr := range addrs {
	if manet.IsIPLoopback(addr) {
	continue
	}
	if isIp6(addr) {
	ip6Ma = addr
	continue
	}
	ip4Ma = addr
	}
	if ip6Ma != nil {
	return []ma.Multiaddr{ip6Ma}
	}
	if ip4Ma != nil {
	return []ma.Multiaddr{ip4Ma}
	}
	return nil
	})

Basically if the leader is a node with both ipv4 and ipv6 interfaces it will choose the ipv6 first. We have a couple of options here. Either as you suggested we allow disabling of ipv6 all together. The other option is to flip the logic to use ipv4 first, which in a scenario where both ipv4 and ipv6 is supported we will use ipv4. This however could be something that other users do not want in a dual stack cluster. Our third option which I am unsure of how that would work is to bind to both interfaces, allowing for either ipv4 or ipv6 p2p connections.

I think the first step is to get a dual stack cluster up and running for e2e tests. The second thing we can do is to look at what other solutions do to solve this issue.