kubernetes/kubernetes

Explore user network namespace for rootless network testing

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#130,926 opened on 2025年3月19日

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help wantedsig/networksig/testingtriage/accepted

説明

Unprivileged network namespaces allow users to create network namespaces and behave as a root inside those namespaces.

This allows to create nftables rules , nested user namespaces and network interfaces

$ unshare -Urn
# ip a
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
root@aojea:~/src/dranet/site# ip link add dummy0 type dummy
root@aojea:~/src/dranet/site# ip a
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 1e:3d:e6:21:85:
# ls -lh /proc/self
lrwxrwxrwx 1 nobody nogroup 0 Feb 28 13:46 /proc/self -> 153429

Currently, for our kube-proxy testing, for complex testing we rely on the great work done by @danwinship with the nftablesTracer, that allows to simulate the packet traversal of the installed nftables rules.

https://github.com/kubernetes/kubernetes/blob/73f54b67b29d77601b0bd42ad8b4992925b9df47/pkg/proxy/nftables/helpers_test.go#L150-L178

However, simulators will never be as reliable as the real thing and also can have the problem to drift if the simulated logic changes.

Using unprivileged network namespaces can COMPLEMENT current testing , not replacing, as these namespaces has some security issues and are relatively new, so maybe are not able to run in each system.

We can just create a predefined topology to emulate the most complex feature and run table tests and multiple combinations just with go test. ./pkg/proxy/nftables/... ... this can be very useful for things like endpoints termination or topology awareness, where all the possible combinations are hard to test with e2e

ns-pod1 ---- ns-kproxy. ---- ns-pod2
                               |
                               |
                               L----- ns-pod3

References

/sig network /cool new thing

cc @aroradaman @adrianmoisey

コントリビューターガイド

技術スタック
goshell
領域
testingbackend
Issue 種別
research
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
3
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
1-2 days
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
active
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
mostly clear
前提条件
Go knowledgeLinux networkingKubernetes basicsnftables familiarity
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
40
調査方針
Explore implementing unprivileged network namespaces in Go tests for kube proxy. Review the existing nftablesTracer at pkg/proxy/nftables/helpers test.go lines 150-178. Examine the reference PR https://github.com/kubernetes sigs/kube network policies/pull/156 for similar approach. Create a predefined network topology for testing endpoint termination and topology awareness as described in the issue. Consider using the 'unshare' and 'ip' commands within Go tests to set up namespaces.
Explore user network namespace for rootless network testing · kubernetes/kubernetes#130926 | Good First Issue