Fix automatic build and update base image

* Revert to amd64 Dockerfile to fix automatic Docker Hub building and add multiarch image separately instead
* Change base image for the building stage to alpine and update the golang version to latest
* Change the entrypoint path for consistency with base image
* Make use of COPY instead of cloning the git repo in the building stage
* Add missing default lua-metrics-file argument as it is required

Dockerfile

@@ -1,23 +1,14 @@
-FROM --platform=$BUILDPLATFORM golang:1.15 AS build
+FROM golang:alpine as build
 
-ARG TARGETOS
-ARG TARGETARCH
-ARG TARGETVARIANT
-
-RUN git clone https://github.com/chr-fritz/fritzbox_exporter.git /go/src/github.com/chr-fritz/fritzbox_exporter
-WORKDIR /go/src/github.com/chr-fritz/fritzbox_exporter
+COPY . /usr/src/fritzbox_exporter
+WORKDIR /usr/src/fritzbox_exporter
 
 RUN go mod download; \
-	case "$TARGETVARIANT" in \
-		v5) export GOARM=5 ;; \
-		v6) export GOARM=6 ;; \
-		v7) export GOARM=7 ;; \
-	esac; \
-	CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH go build -a -ldflags '-w -extldflags "-static"' -o fritzbox-exporter .
- 
-FROM --platform=$TARGETPLATFORM alpine:latest
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -ldflags '-w -extldflags "-static"' -o fritzbox-exporter .
+
+FROM alpine:latest
 RUN apk --no-cache add ca-certificates
-COPY --from=build /go/src/github.com/chr-fritz/fritzbox_exporter/fritzbox-exporter /fritzbox-exporter/
-COPY --from=build /go/src/github.com/chr-fritz/fritzbox_exporter/*.json /etc/fritzbox-exporter/
-ENTRYPOINT ["/fritzbox-exporter/fritzbox-exporter"]
-CMD ["--metrics-file","/etc/fritzbox-exporter/metrics.json","--listen-address","0.0.0.0:8080"]
+COPY --from=build /usr/src/fritzbox_exporter/fritzbox-exporter /bin/
+COPY --from=build /usr/src/fritzbox_exporter/*.json /etc/fritzbox-exporter/
+ENTRYPOINT ["/bin/fritzbox-exporter"]
+CMD ["--metrics-file","/etc/fritzbox-exporter/metrics.json","--lua-metrics-file","/etc/fritzbox-exporter/metrics-lua.json","--listen-address","0.0.0.0:8080"]

Dockerfile.multiarch

@@ -0,0 +1,23 @@
+FROM --platform=$BUILDPLATFORM golang:alpine as build
+
+ARG TARGETOS
+ARG TARGETARCH
+ARG TARGETVARIANT
+
+COPY . /usr/src/fritzbox_exporter
+WORKDIR /usr/src/fritzbox_exporter
+
+RUN go mod download; \
+	case "$TARGETVARIANT" in \
+		v5) export GOARM=5 ;; \
+		v6) export GOARM=6 ;; \
+		v7) export GOARM=7 ;; \
+	esac; \
+	CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH go build -a -ldflags '-w -extldflags "-static"' -o fritzbox-exporter .
+
+FROM --platform=$TARGETPLATFORM alpine:latest
+RUN apk --no-cache add ca-certificates
+COPY --from=build /usr/src/fritzbox_exporter/fritzbox-exporter /bin/
+COPY --from=build /usr/src/fritzbox_exporter/*.json /etc/fritzbox-exporter/
+ENTRYPOINT ["/bin/fritzbox-exporter"]
+CMD ["--metrics-file","/etc/fritzbox-exporter/metrics.json","--lua-metrics-file","/etc/fritzbox-exporter/metrics-lua.json","--listen-address","0.0.0.0:8080"]