Dockerfile with buildkit (experimental support)

Dockerfile

# syntax = docker/dockerfile:experimental
FROM ubuntu:18.04 as build

# This is phase1: the build phase
# where we build our project and output a binary

ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update && apt-get install -y \
    apt-transport-https \
    apt-utils \
    build-essential \
    ca-certificates \
    curl \
    iputils-ping \
    iputils-tracepath \
    jq \
    libgmp-dev \
    lsb-release \
    make \
    netbase \
    software-properties-common \
    unzip \
    xz-utils \
    zlib1g-dev

# Install latest version of Stack
ENV STACK_VERSION=1.9.3
RUN curl -sSL https://github.com/commercialhaskell/stack/releases/download/v$STACK_VERSION/stack-$STACK_VERSION-linux-x86_64.tar.gz | tar xz --wildcards --strip-components=1 -C /usr/local/bin '*/stack'

# Ideally all of the above would go into a "build image" from which we can inherit here
# and just do the stuff below

# Make build directory and copy source
RUN mkdir -p /opt/build
RUN mkdir -p /tmp/out
COPY . /opt/build

# Run the build but make sure to cache .stack and .stack-work
RUN --mount=type=cache,target=/root/.stack \
    --mount=type=cache,target=/opt/build/.stack-work \
    cd /opt/build && \
    stack build --copy-bins --local-bin-path=/tmp/out


FROM fpco/pid1:0.1.2.0

# In this phase we just copy over the prebuilt binary from the above build phase

ENV DEBIAN_FRONTEND=noninteractive

# Some common dependencies we might need with our app
RUN apt-get update && apt-get install -y \
  ca-certificates \
  netbase \
  libgmp-dev

COPY entrypoint.sh /usr/local/bin/entrypoint.sh
RUN chmod +x /usr/local/bin/entrypoint.sh
ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]

RUN mkdir -p /opt/app
COPY --from=build /tmp/out/my-binary /opt/app/

CMD ["/opt/app/my-binary"]

Build using: DOCKER_BUILDKIT=1 docker build -t test .

This requires docker v18.06 (or newer).
See here for more info.