IP pool utilization: break down by floating, ephemeral, SNAT

[david-crespo]

Followup to #5258. Allocated query would have to return a breakdown by type for both IPv4 and IPv6. Should be quite easy: do 6 counts instead of 2 and add AND ip_kind = 'ephemeral' etc. to the WHERE clauses.

omicron/nexus/db-queries/src/db/datastore/ip_pool.rs

Lines 353 to 360 in f8c394f

	.select((
	sql::<BigInt>(
	"count(distinct ip) FILTER (WHERE family(ip) = 4)",
	),
	sql::<BigInt>(
	"count(distinct ip) FILTER (WHERE family(ip) = 6)",
	),
	))

I think the API should still continue to return the total allocated count in addition to the breakdown by type. One of the following:

allocated_ephemeral
allocated_floating
allocated_snat
allocated
capacity

allocated: {
  total
  ephemeral
  floating
  snat
}
capacity

[askfongjojo]

Related: #4958

We may also want to consider displaying internet gateways linked to IP pools or specific IP addresses. (Note: This feature may undergo changes in the future which will possibly make the associations no longer relevant.)

[bnaecker]

I think this is essentially obviated by #8928. That reports usage as a remaining count, which means we can't break things out this way. Also, it's not clear what you'd do with this information. Suppose you see that most addresses are for SNAT. You still need to go look at all your instances to figure out which ones you want to remove. If the addresses are all for Floating IPs...you still need to look at your instances. Instead, we could provide interfaces that make questions like: "Which projects are using more IPs than others?" or "Which instances are older than X and don't use much network?" easy to answer.