[ClusterLabs] Concept of a Shared ipaddress/resource for generic applicatons

[Jan Pokorný]

On 03/12/19 23:38 +0100, Valentin Vidić wrote:
> On Tue, Dec 03, 2019 at 11:14:41PM +0100, Jan Pokorný wrote:
>> The conclusion is hence that even with bleeding edge software
>> collection, there's no real problem in using ipt_CLUSTERIP
>> (when compiled in or alongside kernel) when a proper interface
>> is used, which may boil down to using an appropriate version of
>> iptables command.  The respective logic to select the proper one
>> could be easily extended in the IPaddr2 agent (sorry, I mis-cased
>> this name previously; in a nutshell: if there's iptables-legacy
>> command, prefer that instead), which looks far more attainable
>> than porting to xt_cluster any time soon unless there are
>> volunteers.
> 
> Indeed, I have tested with 2 nodes and TCP connections work as
> expected: packets arrive at both nodes but only one of them
> responds - sometimes the first node and sometimes the second.
> 
> For ARP both nodes respond with the same multicast MAC:
> 
> 22:33:14.231779 ARP, Request who-has 192.168.122.101 tell 192.168.122.1, length 28
> 22:33:14.231833 ARP, Reply 192.168.122.101 is-at 21:53:69:51:3e:b1, length 28
> 22:33:14.231833 ARP, Reply 192.168.122.101 is-at 21:53:69:51:3e:b1, length 28
> 
>> Is there any iptables-legacy command equivalent in Debian?
> 
> Yes, iptables package in Debian installs both:
> 
>   /usr/sbin/iptables-legacy
>   /usr/sbin/iptables-nft
> 
> so the agent can be modified to prefer iptables-legacy over
> iptables.

Perfect, thanks for the affirmation, Valentin.

-> https://github.com/ClusterLabs/resource-agents/pull/1439

For the record, based on my feedback, iptables-extensions man page is
headed to (finally) align with the actual in-kernel deprecation
message:
https://lore.kernel.org/netfilter-devel/20191204130921.2914-1-phil@nwl.cc/
Woot!

-- 
Jan (Poki)
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