cilium: Ensure xfrm state is initialized for route IP before publish #28012
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When rolling cilium-agent or doing an upgrade while running stress test
with encryption a small number of NoStateIn errors are seen. To capture
the error state (a cilium_host IP without an xfrm state rule) you need
to get into the pod near pod init and get somewhat lucky that init
took some longer time. For example I ran `ip x s` in a pod about
15seconds after launch and captured a case with new XfrmInNoErrors,
a cilium_host ip assigned, but no xfrm state rule for it. The packets
received are dropped.
The conclusion is remote nodes learn the new router IP before we have
the xfrm state rule loaded. The remote nodes then start using that
IP for the IPSec tunnel outer IP resulting in the errors when they
reach the local node without the xfrm rule yet. The errors eventually
resolve, but some packets are lost in the meantime.
The reason this happens is because first we configure the datapath
after we push node object updates. This is wrong because we need
to init the ipsec code path before we teach remote nodes about the
new IP. And second the configuration of the datapath does a lookup
in the node objects IPAddresses{} this is only populated from the
k8s watcher in the tunnel case. So we only have the fully populated
node object after we receive it through the k8s watcher. Again its
possible other nodes already have seen the event and started pushing
traffic with the new IPs.
To resolve push IPSec init code to create xfrm rules needed with
the new IPs before we publish them to the k8s node object. And
instead of pulling the IPs out of the node object simply pull them
directly from the node module. This resolves the XfrmInNoState and
XfrmIn*Policy* errors I've seen.
To reproduce the errors I can consistently reproduce with about
30 nodes, with httpperf test running from a pod in all nodes, and
then doing a 'rollout' of the cilium agent for awhile. Seems
a 2-3 hours almost ensures errors pop up. Usually the errors
happen much sooner. Initially I saw these errors on upgrade tests
which is another method to reproduce.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
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Thanks! I left a question below regarding subnetEncryption. Besides that, I was wondering what relationship between this PR and #27724 is?
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When rolling cilium-agent or doing an upgrade while running stress test with encryption a small number of NoStateIn errors are seen. To capture the error state (a cilium_host IP without an xfrm state rule) you need to get into the pod near pod init and get somewhat lucky that init took some longer time. For example I ran
ip x sin a pod about 15seconds after launch and captured a case with new XfrmInNoErrors, a cilium_host ip assigned, but no xfrm state rule for it. The packets received are dropped.The conclusion is remote nodes learn the new router IP before we have the xfrm state rule loaded. The remote nodes then start using that IP for the IPSec tunnel outer IP resulting in the errors when they reach the local node without the xfrm rule yet. The errors eventually resolve, but some packets are lost in the meantime.
The reason this happens is because first we configure the datapath after we push node object updates. This is wrong because we need to init the ipsec code path before we teach remote nodes about the new IP. And second the configuration of the datapath does a lookup in the node objects IPAddresses{} this is only populated from the k8s watcher in the tunnel case. So we only have the fully populated node object after we receive it through the k8s watcher. Again its possible other nodes already have seen the event and started pushing traffic with the new IPs.
To resolve push IPSec init code to create xfrm rules needed with the new IPs before we publish them to the k8s node object. And instead of pulling the IPs out of the node object simply pull them directly from the node module. This resolves the XfrmInNoState and XfrmInPolicy errors I've seen.
To reproduce the errors I can consistently reproduce with about 30 nodes, with httpperf test running from a pod in all nodes, and then doing a 'rollout' of the cilium agent for awhile. Seems a 2-3 hours almost ensures errors pop up. Usually the errors happen much sooner. Initially I saw these errors on upgrade tests which is another method to reproduce.