Merge pull request #9 from microservices-demo/docker/user

Added docker user. Set caps on go binary to allow binding to port 80.

docker/payment/Dockerfile-release

@@ -1,7 +1,20 @@
-FROM busybox:1
+FROM alpine:3.4
+
+ENV	SERVICE_USER=myuser \
+	SERVICE_UID=10001 \
+	SERVICE_GROUP=mygroup \
+	SERVICE_GID=10001
+
+RUN	addgroup -g ${SERVICE_GID} ${SERVICE_GROUP} && \
+	adduser -g "${SERVICE_NAME} user" -D -H -G ${SERVICE_GROUP} -s /sbin/nologin -u ${SERVICE_UID} ${SERVICE_USER} && \
+	apk add --update libcap
 
 WORKDIR /
 EXPOSE 80
 COPY app /
 
+RUN	chmod +x /app && \
+	chown -R ${SERVICE_USER}:${SERVICE_GROUP} /app && \
+	setcap 'cap_net_bind_service=+ep' /app
+
 CMD ["/app", "-port=80"]