I test on V6.4.3 and V6.5.0.
First of all, the configuration template in prometheus.yml.disabled is wrong.
if we enable this module by mv prometheus.yml.disabled to prometheus.yml, will print ERROR as below
2018-12-24T17:08:04.726+0800	ERROR	instance/beat.go:764	Exiting: 1 error: 1 error: missing required field accessing '0.namespace' (source:'/etc/metricbeat/modules.d/prometheus.yml')
we should use the configuration describe in docs:
metricbeat.modules:
- module: prometheus
  metricsets: ["stats"]
  enabled: true
  period: 10s
  hosts: ["localhosts:3816"]
  #metrics_path: /metrics
  #namespace: example
second, it is not working
I start a promethus exporter: /opt/monitor/prometheus/prometheus_node_exporter/node_exporter -web.listen-address=:3816
and use above configuration. metricbeat could start, but no output from the prometheus modules