Enable changing the CIDR on shared networks when no IP ranges are defined

[borisstoyanov]

The required feature described as a wish

As an admin I'd love to be able to change the CIDR of a shared network when there's no IP ranges defined. I appeaciate if there are VMs running they can end up on different CIDRs while on the same network, we want to avoid that. So my suggestion is to check if there are IP ranges defined, if no, this basically means there's no VMs on the network, at this stage this should allow the change of the CIDR, thoughts?

[adietrich-ussignal]

While I am very close to the original request, I think it only partially captures the desired behavior. I feel that having the ability to change the CIDR when one already exists is still a valid behavior that should be accounted for in this, given appropriate guardrails. I would think a CIDR change should also be permitted if no instances exist on said network. Accounting for the virtual router, either have the VR stop when this is performed, or require the operator to stop the VR before changing the CIDR on an existing shared network with a CIDR.

[DaanHoogland]

@adietrich-ussignal , I think this is invalid if VMs are running and have broadcast addresses configured on their NICs. changing the cidr would than

1. allow for adresses outside of the NICs broadcast address be on the same address
2. allow shrinking below the ip address of the VM and
3. allow an IP outside of the CIDR to be on the network.
   I think the original requirement is a minimal restriction if at all enough.

[alexandremattioli]

I'd suggest we start with Boris' proposal, then expand if needed.

[weizhouapache]

IMHO, the gateway/cidr/netmask of Shared network is the information of first IP range. It does not reflect the actual IP ranges of the shared network.

for example, this is supported

• create shared network in 10.10.101.0/24
• add 2nd ip range in 10.10.102.0/24
• add 3rd ip range in 10.10.103.0/24
• update 1st/2nd/3nd ip range with different startip or endip
• delete 1st ip range 10.10.101.0/24

After these actions, the gateway/cidr/netmask is still 10.10.101.0/24, it is not changed.

what I mean is, CIDR can be updated, but users should check the ip ranges of Shared network instead of gateway/cidr/netmask as they are not accurate.