I'd like to hook a new or updated DHCPv4 / DHCPv6 lease.
https://openwrt.org/docs/guide-user/base-system/hotplug_lede indicates that the two ACTION values are "ifup" and "ifdown". It's not clear to me if a renewal of a lease, or a change in leased IPv4 address, IA_NA, or IA_PD will trigger an "ifup" event. (It's well within my knowledge to be able to determine if there was a change, if the updated-lease event can be caught.)
However
suggests that there is an "ifupdate" action as well.
Will "ifup" capture changes in any of the IPv4/IPv6 leases as well as the initial lease granted?
(I'd normally "play" with this myself, but don't have a DHCPv6 server that hands out IA_PDs configured.)
Will invoke /etc/hotplug.d/dhcp/* for lease updates, /etc/hotplug.d/neigh/* for neighbour discovery and expiry events and /etc/hotplug.d/tftp/* for TFTP request events.
Note that this mechanism currently does not cover odhcpd (the default DHCPv6 server). So IPv6 related events only happen if you use dnsmasq to manage both IPv4 and IPv6 DHCP.
Note, those dynamic parameters are decreasing, but also restoring very quickly to their peak values, so it doesn't look like they ever expire.
And there's no leasetime, so I suspect we might not even see ifupdate-event.
It should be either DHCPv6-protocol specification, or DHCPv6-server implementation.