[Feature] Support for node attributes (nodeattrs)

[nielscil]

Use case

I would like to use headscale and NextDNS together. Tailscale supports configuring different profiles using node attributes. This is something I would like to use in headscale too.

In addition some other features also need the use of node attributes, like #2146

Description

This feature request would implement the use of nodeattrs inside the policy file and support nextDNS profile options as metioned in the official tailscale docs.

example of policy

{
	"acls": ["..."],
	"nodeAttrs": [
		{
			"target": ["*"],
			"attr": [
                                "nextdns:abc123",
				"nextdns:no-device-info",
			],
		},
	],
}

this issue is a duplicate of #1407, but is closed because it got stale.

Contribution

• I can write the design doc for this feature
• I can contribute this feature

How can it be implemented?

• Add nodeAttrs to policy file and parse inside ACLPolicy
• Retrieve attributes in mapper.go
• When using NextDNS DOH (already checked in mapper.go)
  • When nextdns-attribute is provided, change the profile of the uri
  • When nextdns:no-device-info is provided, skip adding the extra device info (currently done in mapper.go)
• Add attributes to tnode.CapMap inside tail.go.

[kradalby]

I think we already support nextdns via the config, just not via nodeattrs.

[nielscil]

Yeah, but that is on global level, isn't it? I would like to have different profile for different users.