generators/cloud-init: Add IPv6 to network config

[monstermunchkin]

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[monstermunchkin]

@stgraber, this should fix the ipv6 issue on the Oracle cloud image.

[monstermunchkin]

The problem was that dhcp is an alias for dhcp4, and therefore ipv6 would simply be ignored.

[stgraber]

Hmm, this has the potential for actually breaking a lot of things.
In most cases I would expect enabled dhcpv6 to mean requiring stateful DHCPv6 which LXD does not provide out of the box.

Did you test other distros to make sure this isn't regressing us?

[stgraber]

We don't actually need the system to do DHCPv6 out of the box. Receiving DNS through DHCPv4 is quite fine, we just need it not to disable router advertisements either so the kernel can keep auto-configuring the IPv6 address.

[monstermunchkin]

Did you test other distros to make sure this isn't regressing us?

No, I only tested Oracle to make sure it fixes the issue.

[monstermunchkin]

I'm closing this in favor of lxc/lxc-ci#159.