diff --git a/tools/osbuilder/rootfs-builder/ubuntu/Dockerfile-aarch64.in b/tools/osbuilder/rootfs-builder/ubuntu/Dockerfile-aarch64.in
index 50673b230c..cc0fed0190 100644
--- a/tools/osbuilder/rootfs-builder/ubuntu/Dockerfile-aarch64.in
+++ b/tools/osbuilder/rootfs-builder/ubuntu/Dockerfile-aarch64.in
@@ -11,6 +11,9 @@ FROM ${IMAGE_REGISTRY}/ubuntu:@OS_VERSION@
 # This dockerfile needs to provide all the componets need to build a rootfs
 # Install any package need to create a rootfs (package manager, extra tools)
 
+# Avoid tzdata setup
+ENV DEBIAN_FRONTEND noninteractive
+
 # RUN commands
 RUN apt-get update && apt-get install -y \
     autoconf \
diff --git a/tools/osbuilder/rootfs-builder/ubuntu/config.sh b/tools/osbuilder/rootfs-builder/ubuntu/config.sh
index 20138d145c..d1e0b699d0 100644
--- a/tools/osbuilder/rootfs-builder/ubuntu/config.sh
+++ b/tools/osbuilder/rootfs-builder/ubuntu/config.sh
@@ -7,12 +7,13 @@
 # loaded just before call the function. For more information see the
 # rootfs-builder/README.md file.
 
-OS_VERSION=${OS_VERSION:-18.04}
-# this should be ubuntu's codename eg bionic for 18.04
-OS_NAME=${OS_NAME:-"bionic"}
+OS_VERSION=${OS_VERSION:-20.04}
+# This should be Ubuntu's code name, e.g. "focal" (Focal Fossa) for 20.04
+OS_NAME=${OS_NAME:-"focal"}
 
 # packages to be installed by default
-PACKAGES="systemd iptables init chrony kmod"
+PACKAGES="systemd iptables init kmod"
+EXTRA_PKGS+=" chrony"
 
 DEBOOTSTRAP=${PACKAGE_MANAGER:-"debootstrap"}
 
diff --git a/tools/osbuilder/rootfs-builder/ubuntu/rootfs_lib.sh b/tools/osbuilder/rootfs-builder/ubuntu/rootfs_lib.sh
index e773c62a8f..e94df355db 100644
--- a/tools/osbuilder/rootfs-builder/ubuntu/rootfs_lib.sh
+++ b/tools/osbuilder/rootfs-builder/ubuntu/rootfs_lib.sh
@@ -59,19 +59,10 @@ build_rootfs() {
 	fi
 	# trim whitespace
 	PACKAGES=$(echo $PACKAGES |xargs )
-	EXTRA_PKGS=$(echo $EXTRA_PKGS |xargs)
 	# add comma as debootstrap needs , separated package names.
 	# Don't change $PACKAGES in config.sh to include ','
 	# This is done to maintain consistency
 	PACKAGES=$(echo $PACKAGES | sed  -e 's/ /,/g' )
-	EXTRA_PKGS=$(echo $EXTRA_PKGS | sed  -e 's/ /,/g' )
-
-	# extra packages are added to packages and finally passed to debootstrap
-	if [ "${EXTRA_PKGS}" = ""  ]; then
-		echo "no extra packages"
-	else
-		PACKAGES="${PACKAGES},${EXTRA_PKGS}"
-	fi
 
 	${PKG_MANAGER} --variant=minbase \
 		--arch=${ARCHITECTURE}\
@@ -79,7 +70,7 @@ build_rootfs() {
 		${OS_NAME} \
 		${ROOTFS_DIR}
 
-	chroot $ROOTFS_DIR ln -s /lib/systemd/systemd /usr/lib/systemd/systemd
+	[ -n "${EXTRA_PKGS}" ] && chroot $ROOTFS_DIR apt-get install -y ${EXTRA_PKGS}
 
     # Reduce image size and memory footprint
     # removing not needed files and directories.