A Dockerile to build libzkgroup on ARM v7

zkgroup.Dockerfile

############################
# STAGE 1
# Getting around this bug : https://github.com/docker/buildx/issues/395
# Download files into this temporary image, including .cargo/*
FROM --platform=$BUILDPLATFORM rust:1.49-buster AS rust_fix

RUN apt-get update && \
    apt-get install -y git

RUN git clone https://github.com/signalapp/zkgroup.git /usr/src/zkgroup
WORKDIR /usr/src/zkgroup
ENV USER=root
# Don't do `cargo init` or --> error: `cargo init` cannot be run on existing Cargo packages
# RUN cargo init
RUN mkdir -p .cargo \
  && cargo vendor > .cargo/config



############################
# STAGE 2
# Get the prepared files & build (for ARM)
FROM python:3

# Buggy tzdata installation : https://serverfault.com/questions/949991/how-to-install-tzdata-on-a-ubuntu-docker-image
ARG DEBIAN_FRONTEND=noninteractive
ARG TZ=Europe/Paris

RUN apt-get update && \
    apt-get install -y \
      # rustc must be > 1.36 or libzkgroup build will fail
      # jfsutils to create a FS that works as a workaround for bug
      # wget does not recognizes github certificates so curl replaces it well...
      git zip curl tar cargo rustc make && \
    rm -rf /var/lib/apt/lists/* && \
    update-ca-certificates

# Compiles the native libzkgroup depency for ARM
COPY --from=rust_fix /usr/src/zkgroup /usr/src/zkgroup
WORKDIR /usr/src/zkgroup
#RUN make libzkgroup
# Bypassing the Makefile to add --offline
RUN RUSTFLAGS='-C link-arg=-s' cargo build --release --offline