Switch back to scratch image (fixes #10)

Dockerfile

@@ -1,21 +1,13 @@
-# We're temporarily using Alpine as a base imagine, because there is a bug with
-# health check execution such that it always requires a shell.
-#
-# This issue has been fixed in https://github.com/docker/docker/pull/26208, once
-# this makes it into a Docker release we can switch back to "scratch".
-FROM alpine:3.4
-MAINTAINER James Harris <[email protected]>
+FROM scratch
 
-RUN apk add --update ca-certificates
+ADD http://curl.haxx.se/ca/cacert.pem /etc/ssl/certs/
 
-# Likewise, we can switch back to the "exec" form of HEALTHCHECK once the above
-# fix is released.
-HEALTHCHECK --interval=15s --timeout=500ms CMD /app/bin/healthcheck -check
+HEALTHCHECK --interval=15s --timeout=500ms CMD ["/app/bin/healthcheck"]
 ENTRYPOINT ["/app/bin/honeycomb"]
 
 EXPOSE 8443
 
-ENV CERTIFICATE_PATH      "/"
+ENV CERTIFICATE_PATH      ""
 ENV CERTIFICATE_S3_BUCKET ""
 ENV AWS_ACCESS_KEY_ID     ""
 ENV AWS_SECRET_ACCESS_KEY ""

Makefile

@@ -25,8 +25,7 @@ deploy: docker
 .PHONY: docker-services
 docker-services: docker
 	-docker service rm honeycomb honeycomb-echo
-	-docker network rm honeycomb && sleep 5
-	docker network create --driver=overlay honeycomb
+	-docker network create --driver=overlay honeycomb
 	docker service create \
 		--name honeycomb \
 		--publish 443:8443 \