# 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:3.11} 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 echo "Building Gentoo Container image for ${ARCH} ${SUFFIX} fetching from ${DIST}" \
 && apk --no-cache add ca-certificates gnupg tar wget xz \
 && STAGE3PATH="$(wget -O- "${DIST}/latest-stage3-${MICROARCH}${SUFFIX}.txt" | tail -n 1 | cut -f 1 -d ' ')" \
 && echo "STAGE3PATH:" $STAGE3PATH \
 && STAGE3="$(basename ${STAGE3PATH})" \
 && wget -q "${DIST}/${STAGE3PATH}" "${DIST}/${STAGE3PATH}.CONTENTS.gz" "${DIST}/${STAGE3PATH}.asc" \
 && gpg --list-keys \
 && echo "honor-http-proxy" >> ~/.gnupg/dirmngr.conf \
 && echo "disable-ipv6" >> ~/.gnupg/dirmngr.conf \
 && gpg --keyserver hkps://keys.gentoo.org --recv-keys ${SIGNING_KEY} \
 && gpg --verify "${STAGE3}.asc" \
 && tar xpf "${STAGE3}" --xattrs-include='*.*' --numeric-owner \
 && ( sed -i -e 's/#rc_sys=""/rc_sys="docker"/g' etc/rc.conf 2>/dev/null || true ) \
 && echo 'UTC' > etc/timezone \
 && rm ${STAGE3}.asc ${STAGE3}.CONTENTS.gz ${STAGE3}

FROM scratch

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