It looks like there's a standard approach most Prometheus exporters use when building Dockerfiles, so I'm going to adhere to that. Rather than building the binary inside the container, it's built outside and then copied into the bin dir.

Dockerfile

@@ -1,20 +1,5 @@
-FROM golang:1.8.3-alpine3.6 as builder
+FROM        quay.io/prometheus/busybox:latest
 
-ENV GOOS=linux GOARCH=amd64 GOPATH=/go
+COPY ssl_exporter /bin/ssl_exporter
 
-WORKDIR /go/src/github.com/ribbybibby/ssl_exporter
+ENTRYPOINT ["/bin/ssl_exporter"]
-
-RUN apk --no-cache --quiet add git
-RUN go get "github.com/prometheus/client_golang/prometheus" "gopkg.in/alecthomas/kingpin.v2" "github.com/sirupsen/logrus"
-
-COPY . /go/src/github.com/ribbybibby/ssl_exporter
-
-RUN go build
-
-FROM alpine:3.6
-
-RUN apk add --quiet --no-cache ca-certificates tzdata && rm -rf /var/cache/apk/*
-
-COPY --from=builder /go/src/github.com/ribbybibby/ssl_exporter/ssl_exporter /ssl_exporter
-
-ENTRYPOINT ["/ssl_exporter"]

README.md

@@ -9,6 +9,11 @@ Whatever it is, the SSL exporter gives you visibility over those dimensions at t
 ## Building
     make
     ./ssl_exporter <flags>
+
+### Docker
+    make all docker
+    docker run -p 9219:9219 ssl-exporter:master <flags>
+
 Similarly to the blackbox_exporter, visiting [http://localhost:9219/probe?target=https://example.com](http://localhost:9219/probe?target=https://example.com) will return certificate metrics for example.com. The ```ssl_https_connect_success``` metric indicates if the probe has been successful.
 
 ## Flags