cmd/scollector: count running linux processes from linux.proc collector

[d10v]

Kind of fixes #1079 . The goal is to have something to track if there are no running processes matching from [[Process]] entry and not use since().

[gbrayut]

We would prefer to only count processes that are registered to run or have previously been seen on a system. We use the same toml file for all hosts to simply setup, so we wouldn't want a metric indicating that our mail server process is not running on our backup servers (since it never was suppose to).

Maybe you can add an IncludeCount = true option to the Config/WatchedProc settings so that this feature is disable by default but can be enabled for specific entries. Example where it is not included for puppet-agent but is included for haproxy-t1:

[[Process]]
  Command = "ruby"
  Name = "puppet-agent"
  Args = "puppet"

[[Process]]
  Command = "/haproxy"
  Name = "haproxy-t1"
  Args = "/etc/haproxy-t1/haproxy-t1.cfg"
  IncludeCount = true

[d10v]

@gbrayut updated PR accordingly

[gbrayut]

LGTM!