add setup-alpine script

Signed-off-by: Hiltjo Posthuma <hiltjo@codemadness.org>

misc/setup-alpine

@@ -0,0 +1,42 @@
+#!/bin/sh
+# Things you might want to do after setup:
+# - apk update
+# - apk add alpine-sdk
+# - use misc/run-chroot to chroot to it.
+# - remove gcc, binutils, pkg-config etc packages.
+# - remove libraries such as libpng (png-config), these can mess up
+#   the builds.
+# - remove /usr/include or move to /usr/include.old, note that
+#   python for example uses files from /usr/include/python2.7 at runtime (oh oh).
+# - add a separate morpheus user to build stuff.
+# - copy static plan9 mk to /bin.
+# - copy static git to /bin
+
+set -e -x
+
+mirror="http://nl.alpinelinux.org/alpine/"
+installdir="/ns/alpine"
+tmpdir="${installdir}/tmp"
+
+# fetch apk package tools.
+mkdir -p "${tmpdir}/sbin"
+cd "$tmpdir"
+apktools="apk-tools-static-2.4.4-r0.apk"
+if ! test -f "$apktools"; then
+	wget "${mirror}/v3.0/main/x86_64/${apktools}"
+fi
+if ! test -d "sbin"; then
+	tar -xzf "$apktools"
+fi
+
+# install in chroot.
+"${installdir}/tmp/sbin/apk.static" -X "${mirror}/v3.0/main" -U --allow-untrusted --root "${installdir}" --initdb add alpine-base
+
+# copy etc/resolv.conf
+mkdir -p "${installdir}/etc"
+cp /etc/resolv.conf "${installdir}/etc/resolv.conf"
+chmod 755 "${installdir}/etc/resolv.conf"
+
+# write used mirror as apk repository.
+mkdir -p "${installdir}/etc/apk"
+echo "${mirror}/v3.0/main" > ${installdir}/etc/apk/repositories