Prometheus exporter ci (#84)

* Add CI for prometheus-exporter

build/Dockerfile

@@ -0,0 +1,14 @@
+FROM golang:1.13 as builder
+ARG VERSION
+ARG GIT_COMMIT
+WORKDIR /go/src/github.com/nginxinc/nginx-prometheus-exporter
+COPY *.go ./
+COPY vendor ./vendor
+COPY go.mod go.sum ./
+COPY collector ./collector
+COPY client ./client
+RUN GO111MODULE=on CGO_ENABLED=0 GOOS=linux go build -mod=vendor -a -installsuffix cgo -ldflags "-X main.version=${VERSION} -X main.gitCommit=${GIT_COMMIT}" -o exporter .
+
+FROM alpine:latest
+COPY --from=builder /go/src/github.com/nginxinc/nginx-prometheus-exporter/exporter /usr/bin/
+ENTRYPOINT [ "/usr/bin/exporter" ]

build/ci/Jenkinsfile

@@ -0,0 +1,7 @@
+node {
+  git(
+    url: "${libsLocation}",
+    credentialsId: "${githubCreds}"
+  )
+  load 'nginx-prometheus-exporter/Jenkinsfile'
+}