moby / moby/ipvs

Using this package without ipvs doesn't return error

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Dominant language
Go
Stars
110
Forks
39
PR merge metrics
No merged PRs in 30d

Description

I use you example, slightly modified;

package main

import (
	"log"

	"github.com/moby/ipvs"
)

func main() {
	handle, err := ipvs.New("")
	if err != nil {
		log.Fatalf("ipvs.New: %s", err)
	}
	log.Println("ipvs.New did NOT give an error!!")
	_, err = handle.GetServices()
	if err != nil {
		log.Fatalf("handle.GetServices: %s", err)
	}
	log.Println("handle.GetServices did NOT give an error!!")
}

And run on a kernel where ipvs is not configured. Output:

# moby-example 
WARN[0000] Running modprobe ip_vs failed with message: `modprobe: WARNING: Module ip_vs not found in directory /lib/modules/6.1.0`, error: exit status 1 
ERRO[0000] Could not get ipvs family information from the kernel. It is possible that ipvs is not enabled in your kernel. Native loadbalancing will not work until this is fixed. 
2022/12/23 18:09:43 ipvs.New did NOT give an error!!
2022/12/23 18:09:43 handle.GetServices did NOT give an error!!

So, that ipvs can't be loaded is obviously noted, but even so err==nil is returned.

This is a serious bug, which enforces weird work-arounds do detect if ipvs can be used:

https://github.com/Nordix/kubernetes/blob/68d78c89eccf2d2f381033c836472d53f3ba41c9/pkg/proxy/ipvs/proxier.go#L692-L694

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the provided Go example on a kernel without IPVS and inspect the behavior of ipvs.New and handle.GetServices. Trace how the failed IPVS setup is reported, then make the unavailable-kernel case return an error from the appropriate API and verify that the example no longer logs successful initialization.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
networking
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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