pkg/modprobe from linuxkit/alpine base, using established multistage build onto scratch pattern

Signed-off-by: Isaac Rodman <isaac@eyz.us>

pkg/modprobe/Dockerfile

@@ -0,0 +1,13 @@
+FROM linuxkit/alpine:87a0cd10449d72f374f950004467737dbf440630 AS mirror
+
+RUN mkdir -p /out/etc/apk && cp -r /etc/apk/* /out/etc/apk/
+RUN apk add --no-cache --initdb -p /out \
+    busybox
+RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
+
+FROM scratch
+ENTRYPOINT []
+CMD []
+WORKDIR /
+COPY --from=mirror /out/ /
+LABEL org.mobyproject.config='{"binds": ["/lib/modules:/lib/modules", "/sys:/sys"], "capabilities": ["CAP_SYS_MODULE"]}'

pkg/modprobe/Makefile

@@ -0,0 +1,3 @@
+IMAGE=modprobe
+
+include ../package.mk