Merge pull request #39 from nginx-proxy/cross-compile

build: switch to go cross compilation

Dockerfile.alpine

@@ -1,5 +1,10 @@
 # Build forego
-FROM golang:1.21.5-alpine as go-builder
+FROM --platform=$BUILDPLATFORM golang:1.21.5-alpine as go-builder
+
+ENV CGO_ENABLED=0
+
+ARG TARGETOS TARGETARCH TARGETVARIANT
+ENV GOOS=$TARGETOS GOARCH=$TARGETARCH VARIANT=$TARGETVARIANT
 
 RUN apk add --no-cache musl-dev
 
@@ -9,10 +14,17 @@ WORKDIR /build
 COPY . .
 RUN go mod download
 
-RUN CGO_ENABLED=0 go build -o forego . \
-   && go clean -cache
-
-FROM alpine:3.19.0
+RUN set -eu; \
+	case "$GOARCH" in \
+		arm) export GOARM="${VARIANT#v}" ;; \
+		amd64) export GOAMD64="$VARIANT" ;; \
+		*) [ -z "$VARIANT" ] ;; \
+	esac; \
+	go env | grep -E 'OS=|ARCH=|ARM=|AMD64='; \
+	go build -o forego .; \
+	go clean -cache
+
+FROM --platform=$TARGETPLATFORM alpine:3.19.0
 
 RUN apk add --no-cache bash
 

Dockerfile.debian

@@ -1,16 +1,28 @@
 # Build forego
-FROM golang:1.21.5 as go-builder
+FROM --platform=$BUILDPLATFORM golang:1.21.5 as go-builder
+
+ENV CGO_ENABLED=0
+
+ARG TARGETOS TARGETARCH TARGETVARIANT
+ENV GOOS=$TARGETOS GOARCH=$TARGETARCH VARIANT=$TARGETVARIANT
 
 WORKDIR /build
 
 # Install the dependencies
 COPY . .
 RUN go mod download
 
-RUN CGO_ENABLED=0 GOOS=linux go build -o forego . \
-   && go clean -cache
+RUN set -eu; \
+	case "$GOARCH" in \
+		arm) export GOARM="${VARIANT#v}" ;; \
+		amd64) export GOAMD64="$VARIANT" ;; \
+		*) [ -z "$VARIANT" ] ;; \
+	esac; \
+	go env | grep -E 'OS=|ARCH=|ARM=|AMD64='; \
+	go build -o forego .; \
+	go clean -cache
 
-FROM debian:12.4-slim
+FROM --platform=$TARGETPLATFORM debian:12.4-slim
 
 # Install Forego
 COPY --from=go-builder /build/forego /usr/local/bin/forego