stage3.Dockerfile

# syntax=docker/dockerfile:1

# FIRST LINE IS VERY IMPORTANT. DO NOT MODIFY

# This Dockerfile creates a gentoo stage3 container image. By default it
# creates a stage3-amd64 image. It utilizes a multi-stage build and requires
# docker-17.05.0 or later. It fetches a daily snapshot from the official
# sources and verifies its checksum as well as its gpg signature.

ARG BOOTSTRAP
FROM --platform=$BUILDPLATFORM ${BOOTSTRAP:-alpine:3.19} as builder

WORKDIR /gentoo

ARG ARCH=amd64
ARG MICROARCH=amd64
ARG SUFFIX
ARG DIST="https://ftp-osl.osuosl.org/pub/gentoo/releases/${ARCH}/autobuilds"
ARG SIGNING_KEY="0xBB572E0E2D182910"

RUN <<-EOF
    set -e

    echo "Building Gentoo Container image for ${ARCH} ${SUFFIX} fetching from ${DIST}"

    apk --no-cache add ca-certificates gnupg tar wget xz

    # setup GPG
    gpg --list-keys
    # make sure to have <tab> in following heredoc
    # https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07_04
     cat <<-GPG >> ~/.gnupg/dirmngr.conf
	honor-http-proxy
	disable-ipv6
	GPG
    gpg --keyserver hkps://keys.gentoo.org --recv-keys ${SIGNING_KEY} || \
    	gpg --auto-key-locate=clear,nodefault,wkd --locate-key releng@gentoo.org

    # obtain and extract stage3
    wget -q "${DIST}/latest-stage3-${MICROARCH}${SUFFIX}.txt"
    gpg --verify "latest-stage3-${MICROARCH}${SUFFIX}.txt"
    STAGE3PATH="$(sed -n '6p' "latest-stage3-${MICROARCH}${SUFFIX}.txt" | cut -f 1 -d ' ')"
    echo "STAGE3PATH:" ${STAGE3PATH}
    STAGE3="$(basename ${STAGE3PATH})"
    wget -q "${DIST}/${STAGE3PATH}" "${DIST}/${STAGE3PATH}.CONTENTS.gz" "${DIST}/${STAGE3PATH}.asc"
    gpg --verify "${STAGE3}.asc"
    tar xpf "${STAGE3}" --xattrs-include='*.*' --numeric-owner

    # modify stage3
    ( sed -i -e 's/#rc_sys=""/rc_sys="docker"/g' etc/rc.conf 2>/dev/null || true )
    echo 'UTC' > etc/timezone

    # cleanup
    rm ${STAGE3}.asc ${STAGE3}.CONTENTS.gz ${STAGE3}
EOF

FROM scratch

WORKDIR /
COPY --from=builder /gentoo/ /
CMD ["/bin/bash"]