kola/tests/kubernetes: Use correct GCE variable

Use the private IP because the default firewall
rules do not allow incoming traffic on 2379 for
the public IP.
Also, there are no FLATCAR_*_IP* variables set up in
/etc/environment for machines running in
Google Compute Engine because (as with afterburn)
the prefix is still COREOS_.

kola/tests/kubernetes/controllerInstall.go

@@ -2,7 +2,7 @@ package kubernetes
 
 // https://github.com/coreos/coreos-kubernetes/tree/master/multi-node/generic.
 // The only change besides paramaterizing the env vars was:
-// s/FLATCAR_PUBLIC_IP/FLATCAR_PRIVATE so this works on GCE.
+// s/COREOS_PUBLIC_IP/COREOS_PRIVATE_IPV4 so this works on GCE.
 const controllerInstallScript = `#!/bin/bash
 set -e
 
@@ -54,7 +54,7 @@ function init_config {
     fi
 
     if [ -z $ADVERTISE_IP ]; then
-        export ADVERTISE_IP=$(awk -F= '/FLATCAR_PRIVATE_IPV4/ {print $2}' /etc/environment)
+        export ADVERTISE_IP=$(awk -F= '/COREOS_PRIVATE_IPV4/ {print $2}' /run/metadata/flatcar)
     fi
 
     for REQ in "${REQUIRED[@]}"; do

kola/tests/kubernetes/setup.go

@@ -318,7 +318,7 @@ func runInstallScript(c cluster.TestCluster, m platform.Machine, script string,
 var (
 	etcdConfig = conf.ContainerLinuxConfig(`
 etcd:
-  advertise_client_urls: http://{PUBLIC_IPV4}:2379
+  advertise_client_urls: http://{PRIVATE_IPV4}:2379
   listen_client_urls: http://0.0.0.0:2379
 systemd:
   units:

kola/tests/kubernetes/workerInstall.go

@@ -2,7 +2,7 @@ package kubernetes
 
 // https://github.com/coreos/coreos-kubernetes/tree/master/multi-node/generic.
 // The only change besides paramaterizing the env vars was:
-// s/FLATCAR_PUBLIC_IP/FLATCAR_PRIVATE so this works on GCE.
+// s/COREOS_PUBLIC_IP/COREOS_PRIVATE_IPV4 so this works on GCE.
 const workerInstallScript = `#!/bin/bash
 set -e
 
@@ -43,7 +43,7 @@ function init_config {
     fi
 
     if [ -z $ADVERTISE_IP ]; then
-        export ADVERTISE_IP=$(awk -F= '/FLATCAR_PRIVATE_IPV4/ {print $2}' /etc/environment)
+        export ADVERTISE_IP=$(awk -F= '/COREOS_PRIVATE_IPV4/ {print $2}' /run/metadata/flatcar)
     fi
 
     for REQ in "${REQUIRED[@]}"; do