rootfs: Add template files for new distros

Add template to add new distros.

Added a Makefile to initialize new environment.

Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

rootfs-builder/template/Makefile

@@ -0,0 +1,15 @@
+# Copyright (c) 2017 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+#
+MK_DIR :=$(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
+## Default destdir is one level up where is rootfs.sh script
+DESTDIR ?= "$(realpath $(MK_DIR)/../)/$(ROOTFS_BASE_NAME)"
+all:
+ifndef ROOTFS_BASE_NAME
+	$(error ROOTFS_BASE_NAME is not set, use $ make ROOTFS_BASE_NAME=new_supported_os)
+endif
+	mkdir -p $(DESTDIR)
+	cp "$(MK_DIR)/rootfs_lib_template.sh" "$(DESTDIR)/rootfs_lib.sh"
+	cp "$(MK_DIR)/config_template.sh" "$(DESTDIR)/config.sh"

rootfs-builder/template/config_template.sh

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+# This is a configuration file add extra variables to
+# be used by build_rootfs() from rootfs_lib.sh the variables will be
+# loaded just before call the function.
+
+# Here there are a couple of variables you may need.
+# Remove them or add more 
+
+#Use it rootfs is based in a system has different versions
+OS_VERSION=${OS_VERSION:-DEFAULT_VERSION}
+
+#Mandatory Packages that must be installed
+# systemd: An init system that will start kata-agent
+# iptables: Need by Kata agent
+# udevlib.so: Need by Kata agent
+PACKAGES="systemd iptables udevlib.so"

rootfs-builder/template/rootfs_lib_template.sh

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+# - Arguments
+# rootfs_dir=$1
+#
+# - Optional environment variables
+#
+# EXTRA_PKGS: Variable to add extra PKGS provided by the user
+#
+# BIN_AGENT: Name of the Kata-Agent binary
+#
+# REPO_URL: URL to distribution repository ( should be configured in 
+#           config.sh file)
+#
+# Any other configuration variable for a specific distro must be added 
+# and documented on its own config.sh
+# 
+# - Expected result
+#
+# rootfs_dir populated with rootfs pkgs
+# It must provide a binary in /sbin/init
+build_rootfs() {
+	# Mandatory
+	local ROOTFS_DIR=$1
+
+	#Name of the Kata-Agent binary
+	local BIN_AGENT=${BIN_AGENT}
+
+	# In case of support EXTRA packages, use it to allow
+	# users add more packages to the base rootfs
+	local EXTRA_PKGS=${EXTRA_PKGS:-}
+
+	#In case rootfs is created usign repositories allow user to modify
+	# the default URL
+	local REPO_URL=${REPO_URL:-YOUR_REPO}
+
+	#PATH where files this script is placed
+	#Use it to refer to files in the same directory
+	#Exmaple: ${CONFIG_DIR}/foo
+	local CONFIG_DIR=${CONFIG_DIR}
+
+
+	# Populate ROOTFS_DIR
+	# Must provide /sbin/init and /bin/${BIN_AGENT}
+}