build: perf multi-platform build process

Dockerfile

@@ -1,35 +1,37 @@
 ARG ALPINE="alpine:3.20"
 ARG GOLANG="golang:1.24-alpine3.22"
 
-FROM ${GOLANG} AS xray
+FROM --platform=${BUILDPLATFORM} ${GOLANG} AS xray
 ENV XRAY="25.7.26"
 RUN wget https://github.com/XTLS/Xray-core/archive/v${XRAY}.tar.gz -O- | tar xz
 WORKDIR ./Xray-core-${XRAY}/main/
-RUN go get
-RUN env CGO_ENABLED=0 go build -v -trimpath -ldflags "-s -w"
+RUN go mod download -x
+ARG TARGETARCH
+RUN env GOOS=linux GOARCH=${TARGETARCH} CGO_ENABLED=0 go build -v -trimpath -ldflags "-s -w"
 RUN mv main /xray
 
-FROM ${GOLANG} AS xproxy
+FROM --platform=${BUILDPLATFORM} ${GOLANG} AS xproxy
 RUN apk add git
 COPY ./ /XProxy/
 WORKDIR /XProxy/cmd/
-RUN go get
-RUN env CGO_ENABLED=0 go build -v -trimpath -ldflags "-X main.version=$(git describe --tag) -s -w"
+RUN go mod download -x
+ARG TARGETARCH
+RUN env GOOS=linux GOARCH=${TARGETARCH} CGO_ENABLED=0 go build -v -trimpath -ldflags "-X main.version=$(git describe --tag) -s -w"
 RUN mv cmd /xproxy
 
-FROM ${ALPINE} AS assets
+FROM --platform=${BUILDPLATFORM} ${ALPINE} AS assets
 RUN apk add xz
 RUN wget "https://cdn.dnomd343.top/v2ray-rules-dat/geoip.dat"
 RUN wget "https://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat"
 RUN tar cJf /assets.tar.xz geoip.dat geosite.dat
 
-FROM ${ALPINE} AS release
+FROM --platform=${BUILDPLATFORM} ${ALPINE} AS release
 RUN apk add upx
 WORKDIR /release/run/radvd/
 WORKDIR /release/var/lib/dhcp/
 RUN touch dhcpd.leases dhcpd6.leases
-COPY --from=xproxy /xproxy /release/usr/bin/
 COPY --from=assets /assets.tar.xz /release/
+COPY --from=xproxy /xproxy /release/usr/bin/
 COPY --from=xray /xray /release/usr/bin/
 WORKDIR /release/usr/bin/
 RUN ls | xargs -n1 -P0 upx -9