epmd fails to start in IPv6 environment

[Madhusudan R]

Hello,

I have a Linux box running SLES 11 SP4, with only IPv6 addresses configured on the interfaces. The rabbitMQ version installed on the box is 3.6.15. When rabbitMQ service is started from within our product, it fails as follows:

epmd error for host myhost: address (cannot connect to host/port)

I added the following entries in rabbitmq-env.conf per the suggestion here: https://stackoverflow.com/questions/38343656/epmd-error-for-host-myhost-address-cannot-connect-to-host-port-on-windows-10/41339240

NODE_IP_ADDRESS=127.0.0.1

NODENAME=rabbit@localhost

...but it didn't help.

I ran into these discussion links and would like to know which version of rabbitMQ/erlang to upgrade to to resolve the issue.

https://github.com/erlang/otp/pull/602
https://groups.google.com/forum/#!searchin/rabbitmq-users/ipv6|sort:date/rabbitmq-users/mbsT8PSJTHQ/tjAgsRULBgAJ
https://github.com/rabbitmq/rabbitmq-server/pull/1982

Please let me know if I need to provide additional information.

Thanks,

Madhu

[Madhusudan R]

Sorry, there was a minor issue with rabbitmq-env.conf file and that has been corrected. The epmd and rabbitmq starts up fine with this.

But the question is: Is the issue completely resolved in later releases or should one continue with the aforesaid entry in rabbitmq-env.conf file?

Thanks,
Madhu

[Luke Bakken]

Hi Madhu,

https://github.com/rabbitmq/rabbitmq-server/pull/1982 is available in RabbitMQ 3.7.16. As long as you use the following two variables in rabbitmq-env.conf with that version of RabbitMQ you should have a working IPv6 setup:

SERVER_ADDITIONAL_ERL_ARGS='-proto_dist inet6_tcp'

CTL_ERL_ARGS='-proto_dist inet6_tcp'

Note that the RABBITMQ_ prefix is not necessary in that file.

Thanks,

Luke

[Madhusudan R]

Thanks, Luke.

I'm using rabbitMQ 3.6.14 along with the following entry in rabbitmq-env.conf to get things working in a pure IPv6 environment

NODENAME=rabbit@localhost

Is this good enough for rabbitMQ to work seamlessly in an IPv6 environment (dual stack and pure) or do you recommend that I upgrade to 3.7.16 to avail complete support for IPv6? If an upgrade is needed, which version should erlang/otp be upgraded to?

Thanks, again!
Madhu

[Luke Bakken]

Hi Madhu,

You should use version 3.7.16 with the settings I provided. Since you're upgrading RabbitMQ I suggest upgrading Erlang to the latest version as well.

[Gabriele Santomaggio]

Hi Madhu,

A complete guide about epmd and ipv6 was added here: https://www.rabbitmq.com/networking.html#epmd-ipv6

[Madhusudan R]

Hi Gabriele/Luke,

I have a couple more questions:

1. Does rabbitmq 3.7.16 still support AMQP 0.8.0 or does it work with 0.9.1? Is there a compatibility matrix which depicts this? I'm sorry, but I couldn't find it in this page: https://www.rabbitmq.com/specification.html

2. This page (https://www.rabbitmq.com/amqp-0-8-to-0-9-1.html) looks exhaustive, but is there a page/website which talks about the list of items that have been deprecated from 0.8.0, which when used, would affect the working of the latest version of rabbitmq?

Thanks a lot!
Madhu

[Martin Schröder]

Am Mi., 31. Juli 2019 um 15:51 Uhr schrieb Madhusudan R <madh...@gmail.com>:
> I have a couple more questions:

Then start new thread and don't hijack old ones.

And learn to quote, please.

Best
Martin

[Madhusudan R]

Posted a new question on this.

Thanks,
Madhu

[Madhusudan R]

Hi Luke,

Sorry for the delay in my response. I was integrating rabbitmq 3.7.16 with our product.

Post upgrade to 3.7.16, my observation is that rabbitmq fails to start citing this error:

ERROR: epmd error for host abc: address (cannot connect to host/port)

The following are the entries in rabbitmq-env.conf:

 #NODENAME=rabbit@localhost

SERVER_ADDITIONAL_ERL_ARGS='-proto_dist inet6_tcp'
CTL_ERL_ARGS='-proto_dist inet6_tcp'

If the first line is uncommented, rabbitmq comes up fine. I was under the impression that with rabbitmq upgrade, the NODENAME entry is not needed.

Please advice.

Thanks,
Madhu

[Gabriele Santomaggio]

Your configuration is not totally correct, please follow the guide [1]

>If the first line is uncommented, rabbitmq comes up fine. I was under the impression that with rabbitmq upgrade, the NODENAME entry is not needed.

because the hostname is "localhost", so most likely the lookup is handled by /etc/hosts.

1-https://www.rabbitmq.com/networking.html#distribution-ipv6

-

Gabriele

[Madhusudan R]

Following the documented steps resolved the issue. Thanks, Gabriele!

--Madhu