add the option to specify the family per rule to support ipv6

[dvandok]

This update adds the ability to specify the protocol family. Here's an example:

  iptables:
    service:
      enabled: True
      chain:
        INPUT:
          policy: DROP
          rules:
            - protocol: tcp
              family: ipv4
              source_network: 192.0.2.0/24
              jump: ACCEPT
            - protocol: tcp
              family: ipv6
              source_network: 2001:DB8::/32
              jump: ACCEPT

[cloudlab-autobuild]

Can one of the admins verify this patch?

[fpytloun]

Great and easy approach :-) Only a few inline notes.

When done, squash commits and add Closes: #2 into commit message to link with issue.

[dvandok]

OK, not sure about the squashing. Github supports this when merging, which I can't in this repo.

[fpytloun]

Ad. determining if host is ipv6 capable, I would use this:

{%- if grains.ipv6|default(False) and service.ipv6|default(True) %}

So if there's any IPv6 ip address (including localhost), host is IPv6 capable (eg. doesn't have disabled ipv6 networking). Also it will be possible to override this behavior (disable ipv6 rules in metadata).

[dvandok]

I've incorporated your suggestion.

[fpytloun]

So merging, thank you for your contribution :-)