In gci mounter script, expose /var/lib/kubelet only and add more debugging logs.

cluster/gce/gci/mounter/mounter

@@ -23,14 +23,25 @@ MOUNTER_USER=root
 RKT_BINARY=/home/kubernetes/bin/rkt
 
 function gc {
-    ${RKT_BINARY} gc --grace-period=0s &> /dev/null
+    # Attempt to garbage collect rkt pods with 5 retries.
+    # Rkt pods end up creating new copies of mounts on the host. Hence it is ideal to clean them up right away.
+    attempt=0
+    until [ $attempt -ge 5 ]; do
+	${RKT_BINARY} gc --grace-period=0s && break
+	attempt=$[$attempt+1]
+	sleep 1
+    done
 }
 
 # Garbage collect old rkt containers on exit
 trap gc EXIT
 
+echo "Running mount using a rkt fly container"
+
 ${RKT_BINARY} run --stage1-name="coreos.com/rkt/stage1-fly:1.18.0" \
 	--insecure-options=image \
-	--volume=rootfs,kind=host,source=/,readOnly=false,recursive=true \
-	--mount volume=rootfs,target=/media/root \
+	--volume=kubelet,kind=host,source=/var/lib/kubelet,readOnly=false,recursive=true \
+	--mount volume=kubelet,target=/var/lib/kubelet \
 	docker://${MOUNTER_DOCKER_IMAGE}:${MOUNTER_DOCKER_VERSION} --user=${MOUNTER_USER} --exec /bin/mount -- "$@"
+
+echo "Successfully ran mount using a rkt fly container"
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