fix kernel race condition in DNAT rules for DNS #1228
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…hat the kernel race condition happens less likely. Background see https://blog.quentin-machu.fr/2018/06/24/5-15s-dns-lookups-on-kubernetes/ kubernetes/kubernetes#62628 flannel-io/flannel#1001
mikkeloscar
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Jul 10, 2018
| - hostPath: | ||
| path: /lib/tc | ||
| type: "" | ||
| name: lib-tc |
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What is this volume used for?
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For making "tc" possible to run
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Maybe we could put this folder in the Dockerfile if it's just needed by tc. Then the configuration would be a bit less confusing :) But not a big deal.
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But if anyone else adds also something to tc, then it does not have the xtables.lock, which might do more harm. I think it's good to have it in the hostpath.
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This adds a sidecar into flannel pod spec, that adds a 1-4ms delay for udp port 53 packets going through DNAT, such that the kernel race condition happens less likely.
Background see https://blog.quentin-machu.fr/2018/06/24/5-15s-dns-lookups-on-kubernetes/
kubernetes/kubernetes#62628
flannel-io/flannel#1001 (comment)