The *dch-webhooks* user is used by *dch-webhooks* in order to publish
host information when a new machine triggers its _POST /host/online_
webhook. It therefore needs to be able to write to the
_host-provisioner_ queue (via the default exchange).
The *host-provisioner* user is used by the corresponding consumer to
receive the host information and initiate the provisioning process.
RabbitMQ is an AMQP message broker. It will be used by `xactmon` to
pass messages between the components.
Although RabbitMQ can be deployed in a high-availability cluster, we
don't really need that level of robustness for `xactmon`, so we will
just run a single instance. Deploying a single-host RabbitMQ server
is pretty straightforward.
We're using mTLS authentication; clients need to have a certificate
issued by the *RabbitMQ CA* in order to connect to the message broker.
The `rabbitmq-ca` _cert-manager_ ClusterIssuer issues these certificates
for in-cluster services like `xactmon`.
Dustin