getting toward release

Dockerfile

@@ -0,0 +1,17 @@
+FROM golang:1.13 as builder
+
+WORKDIR /go/src/github.com/sneak/xsum
+COPY . .
+
+RUN go get -v && make build
+
+# this container doesn't do anything except hold the build artifact
+# and make sure it compiles.
+
+FROM alpine
+
+COPY --from=builder /go/src/github.com/sneak/xsum/xsum /bin/xsum
+
+CMD /bin/xsum
+
+# FIXME add testing