25Mb ocaml-graphql-server docker image

Dockerfile

FROM ocaml/opam2:alpine-3.10-ocaml-4.09 as builder
WORKDIR /build

RUN sudo apk update && sudo apk add m4 pkgconfig libressl-dev

RUN opam install \
    bos \
    cohttp \
    crunch \
    astring \
    base64 \
    ocplib-endian \
    digestif \
    cohttp-lwt-unix \
    lwt_ssl \
    graphql-lwt \
    ppx_deriving_yojson \
    graphql-cohttp \
    checkseum \
    ezxmlm \
    ppx_inline_test \
    toml

COPY . .
RUN sudo chown -R opam /build
RUN echo "(lang dune 1.11)" > dune-workspace
RUN echo "(env (_ (flags -cclib -static)))" >> dune-workspace
RUN opam exec -- dune build bin/server.exe
RUN cp ./_build/default/bin/server.exe server.exe

# final image without build cruft
FROM scratch
COPY --from=builder /etc/services /etc/services
COPY --from=builder /etc/ssl/cert.pem /etc/ssl/cert.pem

WORKDIR /app
COPY --from=builder /build/server.exe .
COPY .credentials.toml .
CMD ["./server.exe"]