[BPF] BPFExcludeCIDRsFromNAT allows excluding service IPs from being NATed #8338
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…g NATed
The main use case is node-local dns cache. In iptables mode with k8s
provided kube-proxy, the cache installs such iptables rules that snatch
the traffic before the kube-proxy rules, which would do the NAT.
However, in ebpf NAT is done way before packets may hit iptables. Often
they do not hit iptables at all. Therefore, we need to tell our
kube-proxy, not to translate a service IP that we want to let dns cache
to process.
Unfortunatelly, we cannot annotate the service as the annotations are
not propagate to the kube-proxy code by the k8s front-end.
To setup a node-local dns cache, set BPFExcludeCIDRsFromNAT as follows:
kubedns=`kubectl get svc kube-dns -n kube-system -o jsonpath={.spec.clusterIP}`
BPFExcludeCIDRsFromNAT=$kubedns
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OK, I will merge the pull request when it's ready, leave the commits as is when I merge it, and leave the branch after I've merged it. |
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…v3.27 [release-v3.27] Auto pick #8338: BPFExcludeCIDRsFromNAT allows excluding service CIDRs
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The main use case is node-local dns cache. In iptables mode with k8s provided kube-proxy, the cache installs such iptables rules that snatch the traffic before the kube-proxy rules, which would do the NAT.
However, in ebpf NAT is done way before packets may hit iptables. Often they do not hit iptables at all. Therefore, we need to tell our kube-proxy, not to translate a service IP that we want to let dns cache to process.
Unfortunatelly, we cannot annotate the service as the annotations are not propagate to the kube-proxy code by the k8s front-end.
To setup a node-local dns cache, set BPFExcludeCIDRsFromNAT as follows:
kubedns=
kubectl get svc kube-dns -n kube-system -o jsonpath={.spec.clusterIP}BPFExcludeCIDRsFromNAT=$kubedns
fixes #4689
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