Use CNI_IFNAME environment variable

According to CNI spec kubelet expects CNI_IFNAME (the name
inside container) if sandbox is not empty.

Both python and golang implementation was done unconditionally,
IOW we can add both empty sandbox and interface name on the
host and nonempty sandbox and container's iface name.

Closes-Bug: #1835038
Change-Id: I3f21bc0c0790bb79ee81db361cd072609a0a3169
Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>

kuryr_cni/main.go

@@ -111,7 +111,7 @@ func cmdAdd(args *skel.CmdArgs) error {
 	}
 
 	iface := current.Interface{}
-	iface.Name = vif.VifName
+	iface.Name = args.IfName
 	iface.Mac = vif.Address
 	iface.Sandbox = args.ContainerID
 

kuryr_kubernetes/cni/api.py

@@ -100,7 +100,7 @@ class CNIRunner(object):
         cni_routes_list = result.setdefault("routes", [])
         result["interfaces"] = [
             {
-                "name": vif.vif_name,
+                "name": params["CNI_IFNAME"],
                 "mac": vif.address,
                 "sandbox": self.get_container_id(params)}]
         for subnet in vif.network.subnets.objects:

kuryr_kubernetes/tests/unit/cni/test_api.py

@@ -64,6 +64,7 @@ class TestCNIDaemonizedRunner(test_base.TestCase, TestCNIRunnerMixin):
             'CNI_COMMAND': cni_cmd,
             'CNI_CONTAINERID': 'a4181c680a39',
             'CNI_ARGS': 'foo=bar',
+            'CNI_IFNAME': 'eth0',
         }
         result = self.runner.run(env, m_fin, m_fout)
         m_post.assert_called_with(