Fix up AMD64 dockerfile.

- Add missing PATH.
- Bring into sync with other arches.

docker-image/Dockerfile.amd64

@@ -1,17 +1,22 @@
-FROM amd64/alpine:3.7
+FROM alpine:3.6 as base
 MAINTAINER Shaun Crampton <[email protected]>
 
 # Since our binary isn't designed to run as PID 1, run it via the tini init daemon.
 RUN apk add --update tini
-ENTRYPOINT ["/sbin/tini", "--"]
 
-ADD typha.cfg /etc/calico/typha.cfg
+FROM scratch
+COPY --from=base /sbin/tini /sbin/tini
+COPY --from=base /lib/ld-musl-x86_64.so.1 /lib/ld-musl-x86_64.so.1
+COPY --from=base /lib/libc.musl-x86_64.so.1 /lib/libc.musl-x86_64.so.1
 
-# Put out binary in /code rather than directly in /usr/bin.  This allows the downstream builds
+# Put our binary in /code rather than directly in /usr/bin.  This allows the downstream builds
 # to more easily extract the build artefacts from the container.
-RUN mkdir /code
 ADD bin/calico-typha-amd64 /code/calico-typha
+ADD typha.cfg /etc/calico/typha.cfg
+
 WORKDIR /code
+ENV PATH="$PATH:/code"
 
 # Run Typha by default
+ENTRYPOINT ["/sbin/tini", "--"]
 CMD ["calico-typha"]