[pkg-go] Bug#886893: document how to hook into prometheus

[Antoine Beaupre]

Package: mtail
Severity: wishlist

So I have figured out that mtail can send out metrics as Prometheus
wants them, under /prometheus. But I did this mostly by having my hand
held by the maintainer - there is very little documentation in the
Debian package itself on how to configure it.

It would be nice to have a simple README.Debian file that would say
how to deploy config files (and where) and how to hook it into
Prometheus.

I'm particularly interested in understanding how I can register mtail
in Prometheus under the same host as an already existing node_exporter
instance, so that they can be displayed in (say) the same column in a
Grafana dashboard.

-- System Information:
Debian Release: 9.3
  APT prefers stable
  APT policy: (500, 'stable'), (1, 'experimental'), (1, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-5-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_CA.UTF-8, LC_CTYPE=fr_CA.UTF-8 (charmap=UTF-8), LANGUAGE=fr_CA.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages mtail depends on:
ii  adduser  3.115
pn  daemon   <none>
ii  libc6    2.24-11+deb9u1

mtail recommends no packages.

mtail suggests no packages.