add prometheus metrics prefix

[wthahaha]

when I use prometheus's fedration function, I must filter metrics data, so, I think it should add prefix like "dsc_"...

prometheus.yml

 49   - job_name: 'federation'
 50     scrape_interval: 10s
 51     honor_labels: true
 52     metrics_path: '/federate'
 53     params:
 54       'match[]':
 61         - '{__name__=~"^redis.*"}'
 62         - '{__name__=~"^ipmi.*"}'
 63         - '{__name__=~"^dsc.*"}'

[jelu]

Thanks for the idea! I've reimplemented this using a module option, see man dsc-datatool-output prometheus once you've installed the develop branch.