Set IPv6 sysctls only when IPv6 is enabled

[lorf]

Otherwise when IPv6 is disabled (ipv6.disable=1 on the kernel command line) this error is produced:

TASK [evrardjp.keepalived : Allow consuming apps to bind on non local addresses] *************
ok: [test1] => (item={u'name': u'net.ipv4.ip_nonlocal_bind', u'value': 1})
failed: [test1] (item={u'name': u'net.ipv6.ip_nonlocal_bind', u'value': 1}) => {"ansible_loop_var": "item", "changed": false, "item": {"name": "net.ipv6.ip_nonlocal_bind", "value": 1}, "msg": "Failed to reload sysctl: vm.swappiness = 0\nvm.vfs_cache_pressure = 100\nvm.dirty_background_ratio = 3\nvm.dirty_ratio = 15\nvm.dirty_expire_centisecs = 500\nvm.dirty_writeback_centisecs = 100\nkernel.panic = 10\nnet.core.netdev_max_backlog = 10000\nnet.ipv4.conf.all.log_martians = 1\nnet.ipv4.conf.all.accept_redirects = 0\nnet.ipv4.conf.default.accept_redirects = 0\nnet.ipv4.neigh.default.base_reachable_time_ms = 60000\nnet.core.somaxconn = 262144\nnet.core.rmem_max = 16777216\nnet.core.wmem_max = 16777216\nnet.ipv4.tcp_rmem = 4096 87380 16777216\nnet.ipv4.tcp_wmem = 4096 65536 16777216\nnet.ipv4.tcp_max_tw_buckets = 720000\nnet.ipv4.tcp_fin_timeout = 30\nnet.ipv4.ip_nonlocal_bind = 1\nnet.ipv4.tcp_retries2 = 8\nsysctl: cannot stat /proc/sys/net/ipv6/ip_nonlocal_bind: No such file or directory\n"}
ok: [test1] => (item={u'name': u'net.ipv4.tcp_retries2', u'value': 8})

[evrardjp]

I will have a look when I am back from vacation.

[evrardjp]

I am fine with that. Allow me to fix the CI first.

[evrardjp]

I don't have the rights to push to your branch, do you mind rebasing your code?

[evrardjp]

Hello, can you rebase this?

[lorf]

Sorry, missed Your message. Done.