[baseimage]: let docker in base image use overlay fs instead of aufs

files/build_templates/sonic_debian_extension.j2

@@ -42,6 +42,7 @@ clean_sys() {
 trap_push clean_sys
 sudo LANG=C chroot $FILESYSTEM_ROOT mount sysfs /sys -t sysfs
 
+sudo bash -c "echo \"DOCKER_OPTS=\"--storage-driver=overlay\"\" >> $FILESYSTEM_ROOT/etc/default/docker"
 sudo chroot $FILESYSTEM_ROOT service docker start
 
 # Apply apt configuration files

files/docker/docker.service.conf

@@ -1,3 +1,3 @@
 [Service]
 ExecStart=
-ExecStart=/usr/bin/docker daemon -H fd:// --storage-driver=aufs --bip=240.127.1.1/24 --iptables=false
+ExecStart=/usr/bin/docker daemon -H fd:// --storage-driver=overlay --bip=240.127.1.1/24  --iptables=false