contrib: mkimage script for alpine linux

Docker-DCO-1.1-Signed-off-by: Eivind Uggedal <eivind@uggedal.com> (github: uggedal)

contrib/mkimage-alpine.sh

@@ -0,0 +1,82 @@
+#!/bin/sh
+
+set -e
+
+[ $(id -u) -eq 0 ] || {
+	printf >&2 '%s requires root\n' "$0"
+	exit 1
+}
+
+usage() {
+	printf >&2 '%s: [-r release] [-m mirror] [-s]\n' "$0"
+	exit 1
+}
+
+tmp() {
+	TMP=$(mktemp -d /tmp/alpine-docker-XXXXXXXXXX)
+	ROOTFS=$(mktemp -d /tmp/alpine-docker-rootfs-XXXXXXXXXX)
+	trap "rm -rf $TMP $ROOTFS" EXIT TERM INT
+}
+
+apkv() {
+	curl -s $REPO/$ARCH/APKINDEX.tar.gz | tar -Oxz |
+		grep '^P:apk-tools-static$' -A1 | tail -n1 | cut -d: -f2
+}
+
+getapk() {
+	curl -s $REPO/$ARCH/apk-tools-static-$(apkv).apk |
+		tar -xz -C $TMP sbin/apk.static
+}
+
+mkbase() {
+	$TMP/sbin/apk.static --repository $REPO --update-cache --allow-untrusted \
+		--root $ROOTFS --initdb add alpine-base
+}
+
+conf() {
+	printf '%s\n' $REPO > $ROOTFS/etc/apk/repositories
+}
+
+pack() {
+	local id
+	id=$(tar --numeric-owner -C $ROOTFS -c . | docker import - alpine:$REL)
+
+	docker tag $id alpine:latest
+	docker run -i -t alpine printf 'alpine:%s with id=%s created!\n' $REL $id
+}
+
+save() {
+	[ $SAVE -eq 1 ] || return
+
+	tar --numeric-owner -C $ROOTFS -c . | xz > rootfs.tar.xz
+}
+
+while getopts "hr:m:s" opt; do
+	case $opt in
+		r)
+			REL=$OPTARG
+			;;
+		m)
+			MIRROR=$OPTARG
+			;;
+		s)
+			SAVE=1
+			;;
+		*)
+			usage
+			;;
+	esac
+done
+
+REL=${REL:-edge}
+MIRROR=${MIRROR:-http://nl.alpinelinux.org/alpine}
+SAVE=${SAVE:-0}
+REPO=$MIRROR/$REL/main
+ARCH=$(uname -m)
+
+tmp
+getapk
+mkbase
+conf
+pack
+save