Add wrapper script

Dockerfile

@@ -10,5 +10,6 @@ LABEL org.label-schema.license="MIT" \
       org.label-schema.vcs-url="https://gitlab.b-data.ch/docker/docker-buildx-qemu" \
       maintainer="Olivier Benz <olivier.benz@b-data.ch>"
 
+COPY binfmt.sh /usr/bin/binfmt.sh
 COPY --from=binfmt /usr/bin/ /usr/bin/
 COPY --from=binfmt /usr/bin/binfmt /usr/bin/binfmt

binfmt.sh

+#!/bin/sh
+# Copyright (c) 2021 b-data GmbH.
+# Distributed under the terms of the MIT License.
+
+set -e
+
+BINFMT_ARCHS=`find /usr/bin/ -name 'qemu-*' \
+  | sed 's/.$//' | tr '\n' ' ' | sed 's/.$//'`
+
+if [ -z "$BINFMT_MODE" ]; then
+  BINFMT_MODE=install
+fi
+
+case "$BINFMT_MODE" in
+  install) binfmt --install all ;;
+  update) binfmt --uninstall $BINFMT_ARCHS ; binfmt --install all ;;
+  *) binfmt ;;
+esac