[rabbitmq-discuss] Clustering - just can't get it going

[Derek Wyatt]

Ah, I do have more information though:

DIAGNOSTICS
===========

nodes in question: ['RMQ1']

hosts, their running nodes and ports:
- unable to connect to epmd on RMQ1: nxdomain (non-existing domain)

current node details:
- node name: 'rabbitmqctl1577 at RMQ2'
- home dir: /var/lib/rabbitmq
- cookie hash: ohQKEF09peb6bAgNqawvKA==

And just to be clear, the cookie is the same:

*01*:~$ sudo md5sum /var/lib/rabbitmq/.erlang.cookie
a2140a105d3da5e6fa6c080da9ac2f28  /var/lib/rabbitmq/.erlang.cookie
*02*:~$ sudo md5sum /var/lib/rabbitmq/.erlang.cookie
a2140a105d3da5e6fa6c080da9ac2f28  /var/lib/rabbitmq/.erlang.cookie

Somehow, telnet to epmd works just fine, but something that RMQ is doing
fails to make that happen.  Is there some sort of DNS work that it's doing,
instead of using the hosts files?

i.e. one thing I found is that nslookup fails:

02:~$ nslookup RMQ1
;; Got SERVFAIL reply from <ipaddress>, trying next server
Server: <ipaddress>
Address: <ipaddress>

** server can't find RMQ1: SERVFAIL

But if I ping RMQ1 it works fine.  /etc/nsswitch.conf specifies that files
should be tried first, before DNS w.r.t. hosts.

So, it looks like RMQ is doing something more rigorous to resolve the host,
and I don't know how to change that.  I also don't have access to the DNS
server configuration in order to modify it in any way.



On 25 September 2013 09:57, Jason McIntosh <mcintoshj at gmail.com> wrote:

> Check your erlang cookie on both servers to make sure it matches I think
> it's in - /var/lib/rabbitmq/ - then you can use rabbitmqctl from one
> machine and see if you can connect to another to list queues.  I THINK
> that's rabbitmqctl -n <servernode> list_queues for example.  If both
> servers can talk to each other then it should be rabbitmqctl stop_app,
> join_cluster, start_app.
>
> Jason
>
>
> On Wed, Sep 25, 2013 at 8:50 AM, Derek Wyatt <derek at derekwyatt.org> wrote:
>
>> Hi,
>>
>> I've seen a number of people failing to get clustering running and,
>> unfortunately, I can't get it going either.  Here's the summary of what
>> I've got:
>>
>>    - Two nodes - RMQ1 and RMQ2
>>    - I can ping RMQ1 from RMQ2, and vice versa
>>    - I can telnet from RMQ1 to RMQ2:epmd, and vice versa
>>    - I can telnet from RMQ1 to RMQ2:amqp, and vice versa
>>    - The cookie file is identical, as is clear from the startup INFO
>>
>> My goal is to have RMQ2 join RMQ1 in a cluster.
>>
>> The servers are started using the init script in Ubuntu (i.e. service
>> rabbitmq-server start).  This is different than the script at
>> http://www.rabbitmq.com/clustering.html, which says to start with
>> "rabbitmq-server -detached".  I've tried that and it doesn't seem to make
>> any difference so I always use the init script instead.
>>
>> So, the script says to stop the RMQ2 server and then join the cluster.
>>  The following transcript shows how well all this goes:
>>
>> 02:~$ sudo rabbitmqctl stop_app
>> Stopping node 'rabbit at RMQ2' ...
>> ...done.
>>
>> 02:~$ sudo rabbitmqctl join_cluster --ram rabbit at RMQ1
>> Clustering node 'rabbit at RMQ2' with 'rabbit at RMQ1' ...
>> Error: {cannot_discover_cluster,"The nodes provided are either offline or
>> not running"}
>>
>> However, as I said above, telnetting to the ports works just fine:
>>
>> 02:~$ telnet RMQ1 epmd
>> Trying <ip address>...
>> Connected to RMQ1
>> Escape character is '^]'.
>> booger!
>> Connection closed by foreign host.
>>
>> 02:~$ telnet RMQ1 amqp
>> Trying <ip address>...
>> Connected to RMQ1
>> Escape character is '^]'.
>> booger!
>> AMQP Connection closed by foreign host.
>>
>> I'm stuck for what else to test.  Does anyone know how to troubleshoot
>> this thing further?
>>
>> Thanks,
>> Derek
>>
>>
>> _______________________________________________
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>> rabbitmq-discuss at lists.rabbitmq.com
>> https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss
>>
>>
>
>
> --
> Jason McIntosh
> http://mcintosh.poetshome.com/blog/
> 573-424-7612
>
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>
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