prometheus TCP listener

[Christoph]

Hi,

we noticed that grout starts a listener by default - at least the log 
says so, but since we where unable to connect to it and netstat said
there is no listener on :::9111 we explicitly set it to 127.0.0.1:9111 
using the -M option.
That did not help either - nothing listening on that IP:port.

Is that IP:port expected to be reachable from the Linux host?

The -M documentation also mentions the unix socket option and we managed 
to get it to work using -M unix:/path/...

best regards,
Christoph