Download qemu in container

Dockerfile

@@ -2,8 +2,16 @@ ARG REPO=library
 FROM ${REPO}/python:3-alpine
 
 ARG ARCH=x86_64
-COPY ./build/qemu-${ARCH}-static /usr/bin/
+ARG HOST_ARCH=x86_64
 
+ARG QEMU_VERSION=v2.9.1-1
+
+RUN [ $ARCH == $HOST_ARCH ] || { \
+             wget https://github.com/multiarch/qemu-user-static/releases/download/${QEMU_VERSION}/${HOST_ARCH}_qemu-${ARCH}-static.tar.gz && \
+             tar -xvf ${HOST_ARCH}_qemu-${ARCH}-static.tar.gz && \
+             rm ${HOST_ARCH}_qemu-${ARCH}-static.tar.gz && \
+             mv qemu-${ARCH}-static /usr/bin/ ; \
+             }
 
 RUN echo "OK" > /foo
 

Makefile

@@ -8,7 +8,7 @@ test:
 	@echo ok
 
 .PHONY: build
-build: build/qemu-x86_64-static
+build:
 	docker build . -t ${DOCKER_TAG}
 
 build/qemu-arm-static:
@@ -21,7 +21,7 @@ build/qemu-aarch64-static:
 	./get_qemu.sh
 
 .PHONY: cross-build-arm
-cross-build-arm: build/qemu-arm-static
+cross-build-arm:
 	docker build --build-arg REPO=arm32v6 --build-arg ARCH=arm . -t ${DOCKER_TAG}-arm32v6
 
 .PHONY: run

get_qemu2.sh

@@ -0,0 +1,14 @@
+#! /bin/bash
+
+HOST_ARCH=x86_64
+VERSION=v2.9.1-1
+
+mkdir -p build
+cd build
+
+for target_arch in $*; do
+  wget -N https://github.com/multiarch/qemu-user-static/releases/download/$VERSION/${HOST_ARCH}_qemu-${target_arch}-static.tar.gz
+  tar -xvf ${HOST_ARCH}_qemu-${target_arch}-static.tar.gz
+  rm ${HOST_ARCH}_qemu-${target_arch}-static.tar.gz
+  mv qemu-${target_arch}-static /usr/bin/
+done