On the kube-ovn variants Cilium allocates no pod addresses, but the agent
still takes its router IP and the Gateway API Ingress IP from its
allocation CIDR. In ipam.mode kubernetes that is Node.spec.podCIDR, which
the documented installs slice from the same range kube-ovn allocates pods
from, so kube-ovn sooner or later hands a pod an address Cilium already
holds.
Cilium now runs ipam.mode cluster-pool on the kube-ovn variants, with a
/29 per node from the last /21 of networking.podCIDR, and kube-ovn
excludes that /21 through --default-exclude-ips. The block stays inside
the pod CIDR on purpose. Envoy reaches Gateway API backends from the
node's Ingress IP, and kube-ovn masquerades host-originated traffic only
when the source lies in one of its subnets, so a block outside them such
as 100.65.0.0/16 breaks Gateway API traffic that crosses nodes.
A post-upgrade hook moves existing clusters. It first checks that the
block has a /29 for every node and lies inside kube-ovn's default
subnet, and stops without changing anything otherwise. It adds the block
and every node's current Ingress IP to excludeIps of that subnet,
because the agent keeps a former Ingress IP in its ipcache as
reserved:ingress. It then waits until kube-ovn stops offering the block
and stops if an address in it is still allocated. kube-ovn leaves
excluded addresses out of the subnet status, so that check reads its IP
objects. Then, one node at a time, it clears the inherited /24 from the
CiliumNode, waits for the operator to allocate from the block and
restarts the agent.
networking.podCIDR now needs a prefix of /20 or shorter on the kube-ovn
variants, and the render fails otherwise. A /21 cut into /29s also caps
these variants at 256 nodes.
Assisted-by: LLM
Signed-off-by: Yan Bondarenko <202671653+yankawai@users.noreply.github.com>
(cherry picked from commit dc362fa591)
Signed-off-by: Myasnikov Daniil <myasnikovdaniil2001@gmail.com>
Yan Bondarenko
df320baa14