add oom killer config, so containers die before system daemons, fix #110

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/Dockerfile

@@ -70,6 +70,7 @@ COPY packages/vsudd/vsudd /sbin
 COPY packages/vsudd/etc /etc
 COPY packages/mobyconfig/mobyconfig /usr/bin
 COPY packages/gummiboot/gummiboot.tar.gz /usr/share/src/
+COPY packages/oom/etc /etc
 
 RUN \
   rc-update add swap boot && \
@@ -106,6 +107,7 @@ RUN \
   rc-update add hv_kvp_daemon default && \
   rc-update add hv_vss_daemon default && \
   rc-update add vsudd default && \
+  rc-update add oom default && \
   true
 
 COPY init /

alpine/packages/oom/etc/init.d/oom

@@ -0,0 +1,21 @@
+#!/sbin/openrc-run
+
+description="oom killer settings"
+
+depend()
+{
+	after docker
+}
+
+start()
+{
+	ebegin "Adjusting oom killer settings"
+
+	for f in $(find /run -name '*.pid')
+	do
+		PID=$(cat $f)
+		[ -f /proc/$PID/oom_score_adj ] && echo "-800" > /proc/$PID/oom_score_adj	
+	done
+
+	eend $? "Failed to adjust oom settings"
+}