prometheus-node-exporter-lua: Cannot bind to tailscale0

Package Name

prometheus-node-exporter-lua

Maintainer

@champtar

OpenWrt Version

24.10.5

OpenWrt Target/Subtarget

mediatek/mt7622

Steps to Reproduce

1. Install and setup tailscale following the docs: https://openwrt.org/docs/guide-user/services/vpn/tailscale/start?s[]=open&s[]=general#initial_setup
2. Install prometheus-node-exporter-lua and try to set it to listen in tailscale0:

config prometheus-node-exporter-lua 'main'
	option listen_interface 'tailscale0'
	option listen_port '9100'

3. It never starts properly: defering start until listen interface tailscale0 becomes ready

Actual Behaviour

It never opens up the 9100 port and reports that tailscale0 is not ready which is not true. The interesting thing is that with interface '*' it also listens to tailscale0 as it should.

I think the problem is that tailscale0 is unamanaged, so network_get_ipaddr bind4 "$interface" returns nothing for tailscale0.

Not sure how to fix this. I could do something like but its a bit ugly and hacky:

[ -z "$bind4$bind6" ] && {
    # Fallback for unmanaged interfaces - get IP directly
    bind4=$(ip -4 addr show "$interface" 2>/dev/null | grep -oP 'inet \K[\d.]+' | head -1)
    bind6=$(ip -6 addr show "$interface" 2>/dev/null | grep -oP 'inet6 \K[^/]+' | grep -v '^fe80' | head -1)
}

Thank you.

Confirmation Checklist

• The package is maintained in this repository.
• I understand that issues related to the base OpenWrt repository or LuCI repository will be closed.
• I am reporting an issue for OpenWrt, not an unsupported fork.

Start in the prometheus-node-exporter-lua init script at the network_get_ipaddr bind4 call linked in the issue, and compare its handling of tailscale0 with the wildcard interface. Verify the behavior with the reported configuration and confirm that the exporter starts and opens port 9100 on tailscale0.