[rabbitmq-discuss] rabbitMq use of the setcookie option

Wed Feb 16 09:46:10 GMT 2011

Hi Michael,

On Tue, Feb 15, 2011 at 5:48 PM, Michael De Courci <mdecourci at googlemail.com
> wrote:

> We are trying to understand how cookies are used with Rabbit MQ, from my
> understanding;
> 1) Rabbit MQ servers (rabbitmq-server or rabbitmq-server.bat) can be
> started without the "setcookie" option, in this case they will use the
> cookie defined in the .erlang.cookie file in the user home folder.  If all
> Rabbit MQ servers share the same cookie or .erlang.cookie file, then they
> can communicate
>
> 2) Rabbit MQ servers (rabbitmq-server or rabbitmq-server.bat) can be
> started with the same "setcookie" option, for example, setcookie "FREDABC",where "
> FREDABC" is the shared cookie used to communicate.
>
> Q) What happens when servers use setcookie cookie, see
> http://www.rabbitmq.com/clustering.html#setup, is cookie a variable in the
> script, or is this a misunderstanding ?
>
>
Cookies in Erlang are used by the distributed communication system between
nodes; that is, in Erlang, not AMQP. If you start several Erlang nodes, then
they can only "see" each other and send messages to each other if their
cookies match.

It is something that sits underneath RabbitMQ as part of the Erlang
infrastructure.

If you want to delve deeper, you can find more information here:
http://www.erlang.org/doc/reference_manual/distributed.html#id80929 ,
http://www.erlang.org/doc/man/erlang.html#set_cookie-2 .

Robby
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