Add multi-build Docker file for GCR CI

Dockerfile.ci

@@ -0,0 +1,32 @@
+FROM golang:1.9 as builder
+
+RUN mkdir -p /go/src/github.com/stefanprodan/k8s-podinfo/
+
+WORKDIR /go/src/github.com/stefanprodan/k8s-podinfo
+
+COPY . .
+
+RUN go test $(go list ./... | grep -v integration | grep -v /vendor/ | grep -v /template/) -cover
+
+RUN gofmt -l -d $(find . -type f -name '*.go' -not -path "./vendor/*") && \
+  GIT_COMMIT=$(git rev-list -1 HEAD) && \
+  CGO_ENABLED=0 GOOS=linux go build -ldflags "-s -w \
+  -X github.com/stefanprodan/k8s-podinfo/pkg/version.GITCOMMIT=${GIT_COMMIT}" \
+  -a -installsuffix cgo -o podinfo ./cmd/podinfo
+
+FROM alpine:3.7
+
+RUN addgroup -S app \
+    && adduser -S -g app app \
+    && apk --no-cache add \
+    curl openssl netcat-openbsd
+
+WORKDIR /home/app
+
+COPY --from=builder /go/src/github.com/stefanprodan/k8s-podinfo/podinfo .
+
+RUN chown -R app:app ./
+
+USER app
+
+CMD ["./podinfo"]