Dockerfile.build

# explicitly use Debian for maximum cross-architecture compatibility
FROM debian:trixie-slim

RUN set -eux; \
	dpkgArch="$(dpkg --print-architecture)"; \
	apt-get install --update -y --no-install-recommends \
		ca-certificates \
		sq \
		wget \
		\
		gcc \
		libc6-dev \
		make \
		\
# these are all "arch:all" so we can just install all of them
		libc6-dev-amd64-cross \
		libc6-dev-arm64-cross \
		libc6-dev-armel-cross \
		libc6-dev-armhf-cross \
		libc6-dev-i386-cross \
		libc6-dev-ppc64el-cross \
		libc6-dev-riscv64-cross \
		libc6-dev-s390x-cross \
		\
# the cross-compilers are particular about which architectures they build for, so for now we'll only support a host architecture of amd64 or arm64
		$([ "$dpkgArch" = 'amd64' ] || echo 'gcc-x86-64-linux-gnu') \
		$([ "$dpkgArch" = 'arm64' ] || echo 'gcc-aarch64-linux-gnu') \
		gcc-arm-linux-gnueabi \
		gcc-arm-linux-gnueabihf \
		gcc-i686-linux-gnu \
		gcc-powerpc64le-linux-gnu \
		gcc-riscv64-linux-gnu \
		gcc-s390x-linux-gnu \
		\
		arch-test \
		file \
		patch \
	; \
	apt-get dist-clean

# https://musl.libc.org/releases.html
ENV MUSL_VERSION 1.2.6
RUN set -eux; \
# > Since 1.1.7, releases are signed with the project GPG key. Its fingerprint is 8364 8929 0BB6 B70F 99FF DA05 56BC DB59 3020 450F.
	muslKey='8364 8929 0BB6 B70F 99FF DA05 56BC DB59 3020 450F'; \
#
# Error: No binding signature at time 2025-08-12T23:23:25Z
# because: Policy rejected non-revocation signature (PositiveCertification) requiring second pre-image resistance
# because: SHA1 is not considered secure since 2023-02-01T00:00:00Z
#
# and then:
#
# Error: Policy rejected non-revocation signature (Binary) requiring collision resistance
# because: SHA1 is not considered secure since 2013-02-01T00:00:00Z
# 0 authenticated signatures, 1 bad signature.
#
	sq='sq --policy-as-of 2013-01-01T00:00:00Z'; \
	$sq network search "$muslKey"; \
	$sq pki link add --cert "$muslKey" --userid 'musl libc <musl@libc.org>'; \
	$sq download \
		--output 'musl.tgz' \
		--url "https://musl.libc.org/releases/musl-$MUSL_VERSION.tar.gz" \
		--signature-url "https://musl.libc.org/releases/musl-$MUSL_VERSION.tar.gz.asc" \
		--signer "$muslKey" \
	; \
	\
	mkdir /usr/local/src/musl; \
	tar --extract --file musl.tgz --directory /usr/local/src/musl --strip-components 1; \
	rm musl.tgz

WORKDIR /usr/src/hello
COPY . .

# the following steps are grouped into "architecture families" and roughly ordered in a descending compatibility way such that we end up with the most accurate ".host-arch" symlink we can reasonably get

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='amd64' \
		CROSS_COMPILE='x86_64-linux-gnu-' \
		ARCH_TEST='amd64'
RUN set -ex; \
	make clean all test \
		TARGET_ARCH='i386' \
		CROSS_COMPILE='i686-linux-gnu-' \
		ARCH_TEST='i386'

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='arm64v8' \
		CROSS_COMPILE='aarch64-linux-gnu-' \
		ARCH_TEST='arm64'

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='arm32v7' \
		CROSS_COMPILE='arm-linux-gnueabihf-' \
#		EXTRA_CFLAGS='-march=armv7-a+fp' \
		ARCH_TEST='armhf'
RUN set -ex; \
	make clean all test \
		TARGET_ARCH='arm32v6' \
		CROSS_COMPILE='arm-linux-gnueabi-' \
		EXTRA_CFLAGS='-march=armv6+fp' \
		ARCH_TEST='armhf'
RUN set -ex; \
	make clean all test \
		TARGET_ARCH='arm32v5' \
		CROSS_COMPILE='arm-linux-gnueabi-' \
#		EXTRA_CFLAGS='-march=armv5te' \
		ARCH_TEST='armel'

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='ppc64le' \
		CROSS_COMPILE='powerpc64le-linux-gnu-' \
		EXTRA_CFLAGS='-mlong-double-64' \
		ARCH_TEST='ppc64el'

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='riscv64' \
		CROSS_COMPILE='riscv64-linux-gnu-' \
		ARCH_TEST='riscv64'

RUN set -ex; \
	make clean all test \
		TARGET_ARCH='s390x' \
		CROSS_COMPILE='s390x-linux-gnu-' \
		ARCH_TEST='s390x'

RUN find \( -name 'hello' -or -name 'hello.txt' -or -name '.host-arch' \) -exec file '{}' + -exec ls -lh '{}' +

CMD [".host-arch/hello"]