# Description
The Opsview message queue, based on [Rabbit MQ](🔗) and installed with the `opsview-messagequeue` package, use as a message queueing protocol to send and receive results and notifications between processes and different parts of Opsview.
# Dependencies
It uses our version of Erlang - `opsview-erlang`
# Installation
Refer to [Advanced Automated Installation](🔗).
# Management
Hostname changes
RabbitMQ doesn't handle hostname changes well - reconfiguration or reinstallation of this component is required!
If you rename your messagequeue host after the opsview-messagequeue package has been installed and configured, the data store can no longer be found (as the data is stored in an area keys by the servers hostname) and the server process will not start correctly, effectively losing access to the data. The data store will need to be re-initialized by running the following commands:
If you need to rename the message server, please contact [Support Portal](🔗) for assistance.
## Configuration
#### DPKGs
Watchdog service files are now managed by the package manager, removing the package would leave the watchdog service file behind with a .save extension. Purging the package will remove it. The package manager managed config files are as follows
/opt/opsview/watchdog/etc/services/opsview-messagequeue.conf
#### RPMs
Watchdog service files are now managed by the package manager. When removing the package, if the files listed have been modified by the user before; they will be left behind after rpmsave extension has been added to them. When upgrading the package, if the files listed have been modifed by the user before; the modified file on the disk will remain and the new config file from the upgrading package will be written to the disk with the rpmnew extension. Users will have to:
Manually restore the file with the rpmsave extension.
Rename the rpmnew to the config file name if they want to use the new config for the package.
/opt/opsview/watchdog/etc/services/opsview-messagequeue.conf
There is one other config file which is managed by the package
/opt/opsview/messagequeue/etc/rabbitmq.conf
# Service Administration
The default admin account created is opsview:opsview, which can also be used in the Management UI. To access Management UI enable remote access in Loadbalancer (usually `/opt/opsview/loadbalancer/etc/messagequeue-management-balance.cfg`) and point your browser to http://HOSTNAME:45672/
Opsview message queue logs messages in the /opt/opsview/messagequeue/var/log/rabbit@node-name (normally the hostname of the device where the broker is running.)
As root, start, stop and restart the service using:
# Logging
Opsview message queue logs messages in the `/opt/opsview/messagequeue/var/log/rabbit@node-name` (where `node-name` is the hostname of the device where the broker is running.)
# Variables
The related variable your Opsview Host may need is OPSVIEW_MESSAGEQUEUE_CREDENTIALS _Arguments one and four of this variable are populated by default, being "opsview" and 15672" _Arguments two and three may be obtained (if not already populated) by the below:
#### Argument 2: The messagequeue password
#### Argument 3: The NODENAME, which would be `rabbit@hostname`, where hostname is the full hostname, as from `hostname -f`.
# Troubleshooting
If opsview-messagequeue fails to start on a host during an upgrade, this may be due to its internal data becoming corrupted through an improper shutdown. E.g.
To resolve this you can perform the following steps on the affected host(s):
Then run deploy again.