DHCP include scope statistics

[englm]

Problem Statement

At the moment the DHCP collector lacks information about the scopes, especially how many IPs are in use and available (see also Issue #880 )

Proposed Solution

There is a Powershell command to receive this metrics: Get-DhcpServerv4ScopeStatistics
In background this is leveraging the Get method of the PS_DhcpServerv4ScopeStatistics class
The response is like that

{
    "cmdletOutput": [
        {
            "ScopeId": {
                "Address": 6727872,
                "AddressFamily": 2,
                "ScopeId": null,
                "IsIPv6Multicast": false,
                "IsIPv6LinkLocal": false,
                "IsIPv6SiteLocal": false,
                "IsIPv6Teredo": false,
                "IsIPv4MappedToIPv6": false,
                "IPAddressToString": "192.168.102.0"
            },
            "Free": 11,
            "InUse": 0,
            "Reserved": 0,
            "Pending": 0,
            "AddressesFree": 11,
            "AddressesFreeOnPartnerServer": null,
            "AddressesFreeOnThisServer": null,
            "AddressesInUse": 0,
            "AddressesInUseOnPartnerServer": null,
            "AddressesInUseOnThisServer": null,
            "PendingOffers": 0,
            "PercentageInUse": 0,
            "ReservedAddress": 0,
            "SuperscopeName": "",
            "PSComputerName": null
        }
    ],
    "ReturnValue": 0
}

I played around to make use this cim method englm@bb43a37
At the moment I'm struggling to unmarshal the InstanceA response type.
It would be nice if somebody more familar with the Microsoft MI api in Go could help here. Then I would also be happy to contribute a pull request.

Additional information

No response

Acceptance Criteria

No response

[jkroepke]

It would be nice if somebody more familar with the Microsoft MI api in Go could help here.

The MI API was written by myself for this project, since it seems there is no public project availible. It might be possible, that the API isn't feature complete.

If you could publish your draft as draft Pull Request, I can take a look into it.

The goal is that the data from https://wutils.com/wmi/root/microsoft/windows/dhcp/dhcpserverv4scopestatistics/ is availible in windows_exporter. is that correct?

[englm]

Exactly. My idea is to have:

• AddressesFree
• AddressesFreeOnPartnerServer
• AddressesFreeOnThisServer
• AddressesInUse
• AddressesInUseOnPartnerServer
• AddressesInUseOnThisServer
• PendingOffers
• ReservedAddress

available per scope with the scopeId as label.

@jkroepke you want me to create a draft pull request that you can play with it, right?

[jkroepke]

@jkroepke you want me to create a draft pull request that you can play with it, right?

yes

[englm]

PR #1837
I hope everything is fine, it's my first PR

[jkroepke]

@englm A update from my site: Currently looking into the Win32 API for the DHCP server and I'm going to investigate how I can observe the metric from there:

https://learn.microsoft.com/de-de/previous-versions/windows/desktop/dhcp/dhcp-server-management-api

Based on my experience, I avoid WMI/MI much as I result into a better performance and less memory leaking issues.