Initial delivery of metrics code (#81)

* Initial delivery of metrics code

* Fix build issues

* Fix build issue with go vet

vendor/github.com/prometheus/client_golang/examples/random/Dockerfile

@@ -0,0 +1,20 @@
+# This Dockerfile builds an image for a client_golang example.
+#
+# Use as (from the root for the client_golang repository):
+#    docker build -f examples/$name/Dockerfile -t prometheus/golang-example-$name .
+
+# Builder image, where we build the example.
+FROM golang:1.9.0 AS builder
+WORKDIR /go/src/github.com/prometheus/client_golang
+COPY . .
+WORKDIR /go/src/github.com/prometheus/client_golang/prometheus
+RUN go get -d
+WORKDIR /go/src/github.com/prometheus/client_golang/examples/random
+RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
+
+# Final image.
+FROM scratch
+LABEL maintainer "The Prometheus Authors <prometheus-developers@googlegroups.com>"
+COPY --from=builder /go/src/github.com/prometheus/client_golang/examples/random .
+EXPOSE 8080
+ENTRYPOINT ["/random"]