My company has this Linux VM running strongswan which serves as VPN gateway to a partner. This VM runs on a specific address space to meet IPsec requirements.
We want to replace this VM with a container running in a kubernetes cluster. The question is: how to configure kubernetes so that strongswan can successfully establish connection with external partner?
Update: my cluster will run on Azure cloud. Calico is not supported. Flannel, cilium and Azure CNI are supported.
As comments say Calico is okay, https://docs.projectcalico.org/v3.4/reference/cni-plugin/configuration#requesting-a-specific-ip-address has some details. Basically pick an unused address in your normal pool and add an annotation like "cni.projectcalico.org/ipAddrs": "[\"192.168.0.1\"]" to your pod. Just above that shows how to use multiple IPAM pools which might even be enough if you can use a range rather than a single address.