Rabbitmq
RabbitMQ is a messaging broker, an intermediary for messaging. It gives your applications a common platform to send and receive messages, and your messages a safe place to live until received.
Contents
Installation
Install the rabbitmq package.
Configuration
No configuration should be needed. Simply start the rabbitmq
service.
Default configuration file location /etc/rabbitmq/rabbitmq-env.conf
. See more about configuration on the official docs
Enabling MQTT
RabbitMQ can act as MQTT server. For this functionality to work following plugin needs to be enabled:
sudo -u rabbitmq rabbitmq-plugins enable rabbitmq_mqtt
RabbitMQ service needs to be restarted for this change to take effect.
Clients need to authenticate before they can post to topics. RabbitMQ segregates traffic via virtual hosts, you need to issue `your_user_name:configured_vhost_name` as user name in order bo authenticate.
Enabling HTTP admin
To enable the HTTP admin page:
rabbitmq-plugins enable rabbitmq_management
Then navigate to <ip_address_of_host>:15672
. Default credentials are username:guest password:guest
To allow remote machines to connect to the HTTP admin page edit/create /etc/rabbitmq/rabbitmq.config
:
[{rabbit, [{loopback_users, []}]}].
Troubleshooting
Service stop hangs for a minutes
Rabbitmq package install epmd (Erlang Port Mapping Daemons) as dependency. If you run rabbitmq server via systemd, it will start detached epmd process, that will not be stopped with systemctl stop
. You can avoid this, if add After=epmd.service
in [Unit]
section. Don't forget to reload daemons.
Changed hostname
If you have changed your hostname after you installed rabbitmq, it will no longer be able to start.
This is due to the NODENAME
specified in /etc/rabbitmq/rabbitmq-env.conf
.
Update it to reflect your new hostname, for example:
/etc/rabbitmq/rabbitmq-env.conf
NODENAME=rabbit@my-new-hostname ...
Upgraded RabbitMQ to latest version and cannot start
This might cause your /etc/rabbitmq/rabbitmq-env.conf
to get the wrong NODENAME
.
For example, it might cause it to add another @hostname
part. In any case, this can be fixed by following #Changed hostname.
Erlang cookie error
Failure to authenticate might be caused by a wrong rabbitmq HOME setting:
Authentication failed (rejected by the remote node), please check the Erlang cookie ... home dir: /root
Home can be set in the configuration file:
/etc/rabbitmq/rabbitmq-env.conf
... HOME=/var/lib/rabbitmq ...
can't establish TCP connection
If you see this error then make sure first entry with your host name within /etc/hosts
contains the same IP address as specified within /etc/rabbitmq/rabbitmq-env.conf
(this error is common if you configure rabbitmq to bind to speciffic interface).
References
erlang kernel parameters - kernel parameters for advanced configuration
rabbitmq.config example - rabbitmq.config example (not included with rabbitmq package)