Address issue where genie throws error while assigning multiple veths to a pod

[satyaranjanp]

No description provided.

[satyaranjanp]

This PR addresses issue https://github.com/Huawei-PaaS/CNI-Genie/issues/107

[sushanthakumar]

@satyaranjanp , also mention the reason for this failure due to go version change

[satyaranjanp]

For Go versions older than 1.9, the method Start(), in os/exec/exec.go and is invoked while executing a command, fetches the env and uses it without removing any duplicate entry for a env variable. So when genie tries to set the veth for the second plugin, the env still has the entry for CNI_IFNAME as eth0 that was set for the first plugin. So while the second plugin tries to fetch the veth from env, it gets the older value which was set for the first plugin.

As there can not be two veth in a single container, the plugin fails to assign a veth and an ip.

To address this issue, genie will unset CNI_IFNAME env variable each time it calls a plugin to assigne a ip to pod.

[sushanthakumar]

LGTM