Fix - docker builds for scorecard cron

Fixed the docker build for scorecard cron and as well as updated the
integration to test for the docker builds.

.github/workflows/integration.yml

@@ -84,7 +84,7 @@ jobs:
             ginkgo --focus="E2E TEST:executable|E2E TEST:blob" ./e2e/...
 
       - name: Build docker image
-        run: docker build . --file Dockerfile --tag $IMAGE_NAME
+        run: make dockerbuild
 
       - name: Test docker image
         env:  

Dockerfile.gsutil

@@ -11,12 +11,21 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-FROM golang:1.16 as app
-COPY . /go/src/github.com/ossf/scorecard
-WORKDIR /go/src/github.com/ossf/scorecard
-RUN [ "go", "build", "."]
+
+# syntax = docker/dockerfile:1-experimental
+
+FROM  golang:1.16 as base
+WORKDIR /src
+ENV CGO_ENABLED=0
+COPY go.* ./
+RUN go mod download
+COPY . ./
+
+FROM base AS build
+ARG TARGETOS
+ARG TARGETARCH
+RUN CGO_ENABLED=0 go build -a -tags netgo -ldflags '-w -extldflags "-static"' -o /out/scorecard .
 
 FROM gcr.io/cloud-builders/gsutil
-WORKDIR /go/src/github.com/ossf/scorecard
-COPY --from=app /go/src/github.com/ossf/scorecard /go/src/github.com/ossf/scorecard
-ENTRYPOINT [ "./scorecard" ]
+COPY --from=build /out/scorecard /
+ENTRYPOINT [ "/scorecard" ] 

Makefile

@@ -105,4 +105,5 @@ verify-go-mod: ## Verify the go modules
 dockerbuild: ## Runs docker build
 	$(call ndef, GITHUB_AUTH_TOKEN)
 	docker build . --file Dockerfile --tag $(IMAGE_NAME) 
+	docker build . --file Dockerfile.gsutil --tag $(IMAGE_NAME)-gsutil