Prometheus Exporter should support port range

[cgrinds]

Port Range Prometheus

This solution works well for systemd, native, and containers and

• reduces duplication
• is copy/paste friendly
• much easier to manage

It looks like this:

Exporters:
  prometheus1:
    exporter: Prometheus
    addr: 0.0.0.0
    port_range: 2000-2030
Pollers:
  cluster-01:
    exporters:
    - prometheus1
  cluster-02:
    exporters:
    - prometheus1
  cluster-03:
    exporters:
    - prometheus1

A port range is [inclusive, inclusive] and deterministic. In the example above, cluster-01 will always be assigned port 2000, while cluster-03 will be assigned 2003.

Validate ranges as part of doctor, overflow, overlap, etc.

It probably still make sense to generate the Prometheus target.yml per file SD discussion, but the port range makes that more deterministic.

[rahulguptajss]

• Feature Development
• Unit test cases
• Documentation Update
• Add harvest doctor validation

[rahulguptajss]

@cgrinds could pls take a look at required doc changes for port_range. All other stories are done.

[cgrinds]

Verified on sridevimm RHEL8 system