Dockerfile

ARG BASE="alpine:latest"
FROM alpine:3 as extractor

ARG TARGETARCH
ARG TARGETVARIANT
ARG S6_RELEASE

RUN apk add --no-cache curl jq && \
    if [ -z ${S6_RELEASE} ]; then \
      S6_RELEASE=$(curl -s https://api.github.com/repos/just-containers/s6-overlay/releases/latest | jq -r '.tag_name' | cut -c2-) ;\
    fi && \
    S6_PLATFORM=$(case "${TARGETARCH}/${TARGETVARIANT}" in \
            "arm/v7")   echo "armhf";; \
            "arm64/")   echo "aarch64";; \
	        *)	echo "x86_64";; \
          esac) && \
    echo "Using s6 release ${S6_RELEASE} platform ${S6_PLATFORM}" && \
    curl -sSL "https://github.com/just-containers/s6-overlay/releases/download/v${S6_RELEASE}/s6-overlay-noarch.tar.xz" -o "/tmp/s6-noarch.tar.xz" && \
    curl -sSL "https://github.com/just-containers/s6-overlay/releases/download/v${S6_RELEASE}/s6-overlay-${S6_PLATFORM}.tar.xz" -o "/tmp/s6-arch.tar.xz" && \
    mkdir -p /s6/root && \
    tar -C /s6/root -Jxpf /tmp/s6-noarch.tar.xz && \
    tar -C /s6/root -Jxpf /tmp/s6-arch.tar.xz

FROM $BASE
LABEL maintainer="Julio Gutierrez julio.guti+s6@pm.me"

COPY --from=extractor /s6/root /

ENTRYPOINT [ "/init" ]