Use scratch to support building for more archs (#167)

Support mips64le and 386

.github/workflows/ci.yml

@@ -70,7 +70,7 @@ jobs:
           file: build/Dockerfile
           context: '.'
           target: local
-          platforms: linux/arm,linux/arm64,linux/amd64,linux/ppc64le,linux/s390x
+          platforms: linux/arm,linux/arm64,linux/amd64,linux/ppc64le,linux/s390x,linux/mips64le,linux/386
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache
           tags: nginx/nginx-prometheus-exporter:${{ github.sha }}
@@ -119,7 +119,7 @@ jobs:
           file: build/Dockerfile
           context: '.'
           target: local
-          platforms: linux/arm,linux/arm64,linux/amd64,linux/ppc64le,linux/s390x
+          platforms: linux/arm,linux/arm64,linux/amd64,linux/ppc64le,linux/s390x,linux/mips64le,linux/386
           tags: |
             nginx/nginx-prometheus-exporter:latest
             nginx/nginx-prometheus-exporter:${{ steps.get_version.outputs.GIT_TAG }}

build/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.16-alpine as builder
+FROM golang:1.16 as base
 ARG VERSION
 ARG GIT_COMMIT
 ARG TARGETARCH
@@ -9,20 +9,23 @@ COPY vendor ./vendor
 COPY go.mod go.sum ./
 COPY collector ./collector
 COPY client ./client
+
+FROM base as builder
 RUN GO111MODULE=on CGO_ENABLED=0 GOOS=linux GOARCH=$TARGETARCH go build -mod=vendor -a -ldflags "-s -w -X main.version=${VERSION} -X main.commit=${GIT_COMMIT}" -o nginx-prometheus-exporter .
 
 
-FROM gcr.io/distroless/static-debian10:nonroot as base
+FROM scratch as intermediate
+COPY --from=base /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
 USER 1001:1001
 ENTRYPOINT [ "/usr/bin/nginx-prometheus-exporter" ]
 
 
-FROM base as container
+FROM intermediate as container
 COPY --from=builder /go/src/github.com/nginxinc/nginx-prometheus-exporter/nginx-prometheus-exporter /usr/bin/
 
 
-FROM base as local
+FROM intermediate as local
 ARG TARGETARCH
 ARG TARGETVARIANT
 
-COPY dist/nginx-prometheus-exporter_linux_$TARGETARCH${TARGETVARIANT:+_7}/nginx-prometheus-exporter /usr/bin
+COPY dist/nginx-prometheus-exporter_linux_$TARGETARCH${TARGETVARIANT:+_7}*/nginx-prometheus-exporter /usr/bin/