Change Dockerfile to be a multistage build

The existing Dockerfile produced a broken binary (static
compile caused the binary to segfault).

This patch changes the Dockerfile to

- Build a non-static binary
- Use a multi-stage build: separate stages are used for build and
  deploy; the build stage contains the tools needed for building
  the binary, after which the build artefacts are copied to the
  final stage. which produces the actual image.
  Using this approach, the build-tools can be kept in the Docker
  build-cache, which improves performance of repeated builds and
  does not require cleanup steps in the Dockerfile itself, which
  can simplify the steps.
- The official Python image is used for the build stage, so that
  there is no need to install python manually. The version of python
  is set to the same version as the version used in CI, but can be
  overridden using at build-time using a build-arg:

    docker build --build-arg PYTHON_VERSION=x ..

- Both build- and deploy stages use the debian "stretch" variants,
  which matches what's used in the current version of the Dockerfile,
  but could be updated to the current stable ("buster") variant if
  there is a need.
- The final stage uses the "slim" variant to reduce the size. For
  comparison, below are sizes of the final image when using the
  regular, or "slim" version of the image:

    REPOSITORY  TAG                 IMAGE ID            CREATED             SIZE
    jq          stretch-slim        4b7f380970f0        About a minute ago  70.3MB
    jq          stretch             c5fa8b766cd4        7 minutes ago       119MB

A .dockerignore file is also added to prevent "busting" the Docker
build-cache if not needed, and steps in the Dockerfile are optimized
for BuildKit, but remain compatible with the legacy builder. To build,
and verify the image:

    DOCKER_BUILDKIT=1 docker build -t jq .

And, test the image, us it (for example) to pretty-print its own
"docker image inspect" output:

    docker image inspect jq | docker run -i --rm jq .
    [
      {
        "Id": "sha256:4b7f380970f0d06d4ca9137fbbb3fa3f6554da996147d1d956cda6f44be25650",
        "RepoTags": [
          "jq:latest",
          "jq:stretch-slim"
        ],

Signed-off-by: Sebastiaan van Stijn <[email protected]>

.dockerignore

@@ -0,0 +1,61 @@
+*.o
+*.a
+*.lo
+*.la
+*.lai
+*.so
+*.so.*
+*.gcda
+*.gcno
+*.gcov
+*~
+.*.sw[a-p]
+tags
+
+jq
+!tests/modules/lib/jq/
+jq.1
+
+# Generated source
+src/builtin.inc
+*.pc
+
+# Autotools junk
+.libs
+.deps
+.dirstamp
+libtool
+*.log
+stamp-h1
+config.log
+config.status
+autom4te.cache
+INSTALL
+Makefile
+jq-*.tar.gz
+configure
+aclocal.m4
+Makefile.in
+version.h
+.remake-version-h
+config.cache
+*.rpm
+m4/libtool.m4
+m4/ltoptions.m4
+m4/ltsugar.m4
+m4/ltversion.m4
+m4/lt~obsolete.m4
+tests/*.trs
+
+cscope.in.out
+cscope.out
+cscope.po.out
+jq.dSYM
+
+# Don't bust the build-cache on Dockerfile/.dockerignore only changes
+.dockerignore
+.github
+.travis.yml
+appveyor.yml
+build/*
+docs

Dockerfile

@@ -1,54 +1,54 @@
-FROM debian:9
 
-ENV DEBIAN_FRONTEND=noninteractive \
-    DEBCONF_NONINTERACTIVE_SEEN=true \
-    LC_ALL=C.UTF-8 \
-    LANG=C.UTF-8
+ARG PYTHON_VERSION=3.6.7
 
-COPY . /app
-
-# get dependencies, build, and remove anything we don't need for running jq.
-# valgrind seems to have trouble with pthreads TLS so it's off.
-
-RUN apt-get update && \
-    apt-get install -y \
-        build-essential \
+FROM python:${PYTHON_VERSION}-stretch AS build
+CMD ["bash"]
+ENV LC_ALL=C.UTF-8
+ARG DEBIAN_FRONTEND=noninteractive
+ARG DEBCONF_NONINTERACTIVE_SEEN=true
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends \
         autoconf \
-        libtool \
-        git \
         bison \
-        flex \
-        python3 \
-        python3-pip \
-        wget && \
-    pip3 install pipenv && \
-    (cd /app/docs && pipenv sync) && \
-    (cd /app && \
-        git submodule init && \
-        git submodule update && \
-        autoreconf -i && \
-        ./configure --disable-valgrind --enable-all-static --prefix=/usr/local && \
-        make -j8 && \
-        make check && \
-        make install ) && \
-    (cd /app/modules/oniguruma && \
-        make uninstall ) && \
-    (cd /app && \
-        make distclean ) && \
-    apt-get purge -y \
         build-essential \
-        autoconf \
-        libtool \
-        bison \
-        git \
         flex \
-        python3 \
-        python3-pip && \
-    apt-get autoremove -y && \
-    rm -rf /app/modules/oniguruma/* && \
-    rm -rf /app/modules/oniguruma/.git && \
-    rm -rf /app/modules/oniguruma/.gitignore && \
-    rm -rf /var/lib/apt/lists/* /var/lib/gems
+        git \
+        libtool \
+ && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# Install docs dependencies; we're only copying the Pipfile here,
+# so that this is only run again if dependencies change
+RUN  pip3 install pipenv
+COPY docs/Pipfile docs/Pipfile.lock ./docs/
+RUN  cd docs && pipenv sync
+
+COPY .gitmodules .
+COPY .git        ./.git/
+RUN git submodule init
+RUN git submodule update
+RUN sed -i.bak '/^AM_INIT_AUTOMAKE(\[-Wno-portability 1\.14\])$/s/14/11/' modules/oniguruma/configure.ac
+
+COPY . .
+RUN autoreconf -if
+RUN ./configure --disable-valgrind --with-oniguruma=builtin YACC=/usr/bin/bison --prefix=/build/
+RUN make BISON_PKGDATADIR=/usr/bin/bison src/parser.c || make src/parser.c
+RUN make -j8
+RUN make check -j8
+RUN make install
+RUN /build/bin/jq -V
+
+# Collect the files for the final image
+FROM debian:stretch-slim AS deploy
+ENV LC_ALL=C.UTF-8
+ARG DEBIAN_FRONTEND=noninteractive
+ARG DEBCONF_NONINTERACTIVE_SEEN=true
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends man \
+ && rm -rf /var/lib/apt/lists/*
 
+COPY --from=build /build/.  /usr/local/
+RUN jq -V
 ENTRYPOINT ["/usr/local/bin/jq"]
-CMD []
+CMD ["--help"]