add build-cross for local cross building

Makefile

@@ -3,4 +3,18 @@ build:
 	CGO_ENABLED=1 go build -mod=vendor -o service main.go
 
 build-static:
-	CGO_ENABLED=1 go build -mod=vendor -tags=embed -o service main.go
+	CGO_ENABLED=1 go build -mod=vendor -tags=embed -o service main.go
+
+build-armhf:
+	GOARCH=arm \
+	ARCH=armhf \
+	DEPS="gcc-arm-linux-gnueabihf libc6-dev-armhf-cross" \
+	PREFIX=arm-linux-gnueabihf \
+	./build-cross.sh
+
+build-arm64:
+	GOARCH=arm64 \
+	ARCH=arm64 \
+	DEPS="gcc-aarch64-linux-gnu libc6-dev-arm64-cross" \
+	PREFIX=aarch64-linux-gnu \
+	./build-cross.sh

build-cross.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+GOVERSION=${GOVERSION:-1.20.5}
+CONTAINER=${PREFIX}-${ARCH}
+
+# prepare
+podman build -t ${CONTAINER} -f - <<EOF
+  FROM debian:stable-slim
+
+  RUN dpkg --add-architecture ${ARCH}
+  RUN apt-get update && apt-get install --yes --no-install-recommends make curl ca-certificates libgstreamer1.0-dev:${ARCH} libgstreamer-plugins-base1.0-dev:${ARCH} ${DEPS}
+
+  WORKDIR /go
+  RUN curl -L "https://go.dev/dl/go${GOVERSION}.linux-amd64.tar.gz" | tar xzf - --strip-components 1
+  ENV PATH "$PATH:/go/bin"
+
+  ENV CGO_ENABLED 1
+  ENV GOOS "linux"
+  ENV GOARCH "${GOARCH}"
+  ENV CC "${PREFIX:+$PREFIX-}gcc"
+  ENV PKG_CONFIG_PATH "/usr/lib/${PREFIX}/pkgconfig"
+EOF
+
+podman run \
+  --rm \
+  --volume ./:/data \
+  --workdir /data \
+  ${CONTAINER} \
+  go build -mod=vendor -tags=embed -o service-${GOOS}-${GOARCH} main.go