openwrt-builder: dockerfile for an openwrt builder

This is a base builder -- it sets up *most* of the
environment right and provides a great cache; later we can git pull
again and check out the right commit, without needing to invalidate
this builder and re-clone OpenWrt again.

openwrt-builder-entry.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+[ -x /input.sh ] && /input.sh
+
+cd /builder/openwrt && /usr/bin/screen "$@"
+
+[ -x /output.sh ] && /output.sh

openwrt-builder.dockerfile

@@ -2,8 +2,14 @@ FROM builder
 
 USER buildbot
 
-WORKDIR /builder/openwrt
+WORKDIR /builder
 
-RUN git clone https://git.laboratoryb.org/hurricos/openwrt-mirror --branch master .
+RUN git clone https://git.laboratoryb.org/hurricos/openwrt-mirror --branch master openwrt
 
+ENV openwrt_dir=/builder/openwrt
 
+RUN cd ${openwrt_dir} && ./scripts/feeds update -a && ./scripts/feeds install -a
+
+COPY openwrt-builder-entry.sh /openwrt-builder-entry.sh
+
+ENTRYPOINT [ "/openwrt-builder-entry.sh" ]