fix multus config file generation to avoid self-delegation

[thomasferrandiz]

Add a check to make sure that we don't use an existing multus configuration file. This avoids creating a situation where multus delegates to itself and breaks pod networking by trying multiple times to create the same intefarce for a pod.

This should fix: #1130

[s1061123]

Currently thin_entrypoint creates 00-multus.conf or 00-multus.conflist. So could you please use "00-multus.conf{,list}" to match the multus generated file?

[thomasferrandiz]

done, thanks for the input.

[coveralls]

coverage: 64.099% (+0.3%) from 63.783% when pulling ea7f19b on thomasferrandiz:delegateAdd-bug into d5883bd on k8snetworkplumbingwg:master.

[s1061123]

I locally tested simpe go code from your PR code and found that your code still choose 00-multus.conf, hence your code does not fix this issue. Please check your code?

package main

import (
        "fmt"
        "path"
        "regexp"
)

func main() {

        filePathLists := []string{
                "/host/etc/cni/net.d/00-multus.conf",
                "/host/etc/cni/net.d/10-flannel.conflist",
        }

        multusRegexp, err := regexp.Compile("00-multus.conf{,list}")
        if err != nil {
                fmt.Printf("regexp compilation failed: %v", err)
                return
        }
        masterConfigPath := ""

        for _, filename := range filePathLists {
                if !multusRegexp.MatchString(path.Base(filename)) {
                        masterConfigPath = filename
                        break
                }
        }
        fmt.Printf("masterConfigPath: %s\n", masterConfigPath)
        return
}

$ go run test.go
masterConfigPath: /host/etc/cni/net.d/00-multus.conf

[s1061123]

File another PR for this issue: #1142 so let me close this PR.

[thomasferrandiz]

The original PR without the modification you requested actually worked.

After testing, the correct regexp would be regexp.Compile("00-multus.(conf|conflist)").