Add new parameters for collector.service: services-list and custom labels

[peekjef72]

replace previous PR PR#1180

This PR adds some feature to service collector:

• add config parameter collector.service.services-list with a comma separated list of service names:

collector:
 service:
   services-list: windows_exporter, winRM, pushprox_client, Dhcp

the param will only be checked if services-where is not set.
the list will be used to build a service-where query based on Name and is equivalent to:

collector:
  service:
    services-where: "Name = 'elmt_1' or Name = "elmt_X' or ..."

• add a new parameter that can only be set in config file:
  It allows to set any number of custom labels value for each service:
  e.g.:

collector:
  service:
    services:
      windows_exporter:
        application: prometheus
        custom1: val1
      pushprox_client:
        application: prometheus
        custom1: val1
      winRM:
        application: windows
        custom1: val2
      Dhcp:
        application: windows
        custom1: val3

Use case: allow to build a generic Prometheus alert on not running service and to use the specified associated labels to drive a specific behavior. For me they are used to route for a specific documentation based on context.

Label's names must be identical for each service. Not identical labels names are removed !
This parameter as a lower priority than service-where and service-list.
It accepts a dict (see above example) or a list; in this case it behaves like services-list.
e.g.:

collector:
  service:
    services:
      - dhcp
      - pushprox_client
      - windows_exporter
      - winRM

Then generic alert services:

groups:
- name: Window Server Alerts
  rules:

  # Sends an alert when the 'sqlserveragent' service is not in the running state for 3 minutes.
  - alert: WindowServiceNotRunning
    expr: windows_service_state{state="running"} == 0
    for: 3m
    labels:
      severity: high
    annotations:
      summary: "Service {{ $labels.name }} for {{ $labels.application }} down for 3 min."
      description: "Service {{ $labels.name }} for Application {{ $labels.application }} on instance {{ $labels.instance }} has been down for more than 3 minutes."

[breed808]

I've been reviewing each commit individually, and it appears they may be out of order?
9d8270f fails to build:

$ git status
HEAD detached at 9d8270f
...
$ go build
# github.com/prometheus-community/windows_exporter/collector
collector/init.go:17:33: undefined: config.ConfigHook
collector/init.go:253:21: undefined: ServiceBuildHook
collector/collector.go:59:51: undefined: config.ConfigHook
collector/collector.go:62:87: undefined: config.ConfigHook
collector/collector.go:85:38: undefined: config.ConfigHook

[breed808]

It's be worth adding a log entry here, to prevent user confusion in the event of a failure.

[peekjef72]

I've been reviewing each commit individually, and it appears they may be out of order? 9d8270f fails to build:

$ git status
HEAD detached at 9d8270f
...
$ go build
# github.com/prometheus-community/windows_exporter/collector
collector/init.go:17:33: undefined: config.ConfigHook
collector/init.go:253:21: undefined: ServiceBuildHook
collector/collector.go:59:51: undefined: config.ConfigHook
collector/collector.go:62:87: undefined: config.ConfigHook
collector/collector.go:85:38: undefined: config.ConfigHook

I'm a little bit confused with what you have tried to do.
I have committed files by group of changes ( what they do), not by independant function.
The program globally compiles. That is all I can say.
Do you prefer I post a single global commit ?

[breed808]

You're on the right track; each commit should be a self-contained change.
However 9d8270f wasn't self-contained as it referenced objects that didn't exist (config.ConfigHook, ServiceBuildHook, config.ConfigHook).

These were likely introduced in a later commit. Interactively rebasing the feature branch such that 9d8270f occurs after the commit introducing these objects should have worked.

A single, global commit does work but can become difficult to review once it reaches a certain size.