add Dockerfile

Dockerfile

+FROM golang:alpine
+
+COPY cdn-origin.go $GOPATH/src/github.com/whats-this/cdn-origin/
+COPY prometheus/ $GOPATH/src/github.com/whats-this/cdn-origin/prometheus/
+COPY weed/ $GOPATH/src/github.com/whats-this/cdn-origin/weed/
+
+RUN apk add --no-cache --virtual .build-deps git && \
+
+    go-wrapper download github.com/lib/pq && \
+    go-wrapper download github.com/prometheus/client_golang/prometheus && \
+    go-wrapper download github.com/Sirupsen/logrus && \
+    go-wrapper download github.com/spf13/pflag && \
+    go-wrapper download github.com/spf13/viper && \
+    go-wrapper download github.com/valyala/fasthttp && \
+
+    go-wrapper install github.com/whats-this/cdn-origin && \
+    apk del .build-deps
+
+WORKDIR $GOPATH/src/github.com/whats-this/cdn-origin
+ENTRYPOINT ["go-wrapper", "run"]