RabbitMQ module path_prefix

[xadcoh]

Hello.

This issue based on https://discuss.elastic.co/t/rabbitmq-module-path-prefix/127292

When RabbitMQ configured with option:
management.path_prefix = /<prefix>
Metrics can't be collected with:

metricset: ["node", "queue"]
hosts: ["<ip>:15672"]

Error is:
HTTP error 406 in node: 406 Not Acceptable
This is expected behavior because there is no option for prefix in module config. Metricbeat will try to reach RabbitMQ with:

<ip>:15672/api/queues
<ip>:15672/api/nodes

In this example correct paths are:

<ip>:15672/rabbit/api/queues
<ip>:15672/rabbit/api/nodes

Workaround is point metricbeat with full path.
Nodes:

- module: rabbitmq
  metricsets: ["node"]
  period: 10s
  hosts: ["<ip>:15672/rabbit/api/nodes"]
  username: rabbitmetricbeatuser
  password: strongpass

Queues:

- module: rabbitmq
  metricsets: ["queue"]
  period: 10s
  hosts: ["<ip>:15672/rabbit/api/queues"]
  username: rabbitmetricbeatuser
  password: strongpass

For confirmed bugs, please report:

• Version:
  metricbeat: 6.2.3
  kibana: 6.2.2
  elasticsearch: 6.2.2
• Operating System:
  centos 7
• Steps to Reproduce:

1. Install RabbitMQ
2. Put management.path_prefix = /<prefix> in /etc/rabbitmq/rabbitmq.conf
3. Install metricbeat
4. Configure rabbitmq module:

- module: rabbitmq
  metricsets: ["node", "queue"]
  period: 10s
  hosts: ["<ip>:15672"]
  username: rabbitmetricbeatuser
  password: strongpass

[jsoriano]

Fixed in #7074