[RFE]To achieve fixed IP assignment through Whereabouts, ensuring that the IP address remains unchanged regardless of pod restarts.

[fanhao99]

Our scenario is to bind EIPs to pods using Whereabouts. However, the current issue is that the pod’s IP changes whenever the pod restarts. What method can we use to ensure a fixed IP is bound to a specific pod name?

[mlguerrero12]

You can use a stateful set

[fanhao99]

Thank you for the response. I’m already using a StatefulSet, but when I scale the replicas, there’s still a chance that the IP might get assigned to a different pod. Is there a way to permanently bind a specific IP address to a specific pod, ensuring that the IP is always reserved for that pod no matter what?

[fanhao99]

If I want to modify the code so that an IPReservation is always retained — even when the replica count is set to 0 — and then re-associated with the same Pod name when the replica count is increased back to 1, which files should I modify?

[mlguerrero12]

Whereabouts allocates the first available IP, and a stateful set only creates a new pod when the previous one is deleted. So, in theory, it should get the same IP when you set the replica to 0 and then back to 1.

Are you able to reproduce this? Could you share more info about it?

[fanhao99]

That understanding is completely correct. However, there’s one issue: when A sets the number of replicas in the StatefulSet to 0, and at the same time B changes the replica count from 0 to 1, it can result in B using the IP address that originally belonged to A.

[fanhao99]

Since the IPs are assigned in ascending order, how can I resolve this issue? I want the IP used by A to be reserved when A sets its replicas to 0, so that it won’t be taken by other users.

[mlguerrero12]

Do you mean that both A and B have their own statefulSet objects?

You can create 2 different network-attachment-definitions with different whereabouts parameters. You can play with the range_start and range_end parameter using the same ip range. I've seen users doing that in production to control the ip allocations.

Restricting to 1 for this particular case.

[fanhao99]

I’m working with multiple StatefulSets, and for each one, I should create a separate NetworkAttachmentDefinition with a specific IP range (using range_start and range_end) to ensure the IPs are clearly assigned to each StatefulSet. Is that correct? Thanks!

[mlguerrero12]

they could have the same ip range but different range_start and range_end or you could have multiple 2 (/30) ip ranges.
I've seen both scenarios