builder/makepkg-overlay

#!/usr/bin/env bash

cleanup() {
	umount "$cnt_dir/rootfs"
}

wrk_dir='/home/lxc'
pkg_url=$1
pkg_dest=$2

cnt="_makepkg.$$"
cnt_dir="$wrk_dir/containers/$cnt"

trap 'cleanup' INT TERM EXIT

lxf -r builder -i builder new "$cnt"

# Add the build script
cp "$wrk_dir/files/buildpackage" "$cnt_dir/rootfs/init"
chmod 755 "$cnt_dir/rootfs/init"

# Tell it where to fetch the package
echo "$pkg_url" > "$cnt_dir/rootfs/repo"

export PKG_GIT_URL="$pkg_url"

# Start the container
lxc-start -n "$cnt" -F; lxc_exit=$?
(( lxc_exit )) && exit "$lxc_exit"

# Put the artifacts where asked to
[[ "$pkg_dest" ]] && {
	artifacts=( "$cnt_dir/rootfs/buildroot/"*.pkg.* )

	for i in "${artifacts[@]}"; do
		i_name="${i##*/}"

		printf 'Found artifact: %s\n' "$i_name"
		
		if [[ -f "$pkg_dest/$i_name" ]]; then
			echo "$pkg_dest/$i_name already exists, not overwriting."
		else
			cp -vn "$i" "$pkg_dest"
		fi
	done
}