Ensure Gateway Address Uniqueness

[danehans]

#360 specifies the need to add support for user-defined Gateway addresses. When multiple Gateways exist with user-defined addresses, an address conflict may arise. EG should check the user-defined addresses across the managed Gateways and ensure that they are unique.

[shawnh2]

this issue is related to #360, i will have a stab at this after #1259 and #1322 merged

plz assign

[shawnh2]

since #1601 merged, it occurs to me that if we had some mechanism to ensure the uniqueness of gateway address in the first place, the gateway with duplicate address should never be ready, and will save us a lot of enery to debug it.

so, i propose to add a gloabl Set structure, probably a field AllocatedGatewayIPAddresses in gateway controller:

gateway/internal/provider/kubernetes/controller.go

Line 62 in f466430

type gatewayAPIReconciler struct {

what it does is pretty simple, it checks whether the IP address has been allocated by other gateway before add it into Set, we could write the logic in here: (it only happens if we run gateway in LoadBalancer mode)

gateway/internal/status/gateway.go

Line 38 in f466430

if svc.Spec.Type == corev1.ServiceTypeLoadBalancer {

if we find the addr is duplicated, we shall surface the gateway with Programmed: False.

as for deletion, we can delete the addr along with gateway resources:

gateway/internal/provider/kubernetes/controller.go

Lines 965 to 967 in f466430

	func(update message.Update[types.NamespacedName, *gwapiv1b1.GatewayStatus]) {
	// skip delete updates.
	if update.Delete {

cc @arkodg

[arkodg]

@shawnh2 I like the idea, the only issue I see is the logic to implement this will be sprinkled into multiple areas and packages which maybe hard to maintain in the long run

[shawnh2]

agree.

also i think this is not like something we must implement, it's more like a insurance. for now, we may rarely encounter this problem, so it would be nice to keep this as an optional feature.

[arkodg]

sure, agreed, lets leave this open until a need arises in the future

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days.