New staged build system based on DESIGN.md (#4)

Author: cmeister2

.travis.yml

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+language: minimal
+
+script:
+  # Run all stages in one stage at the moment. Docker images are not shared
+  # between stages.
+  - ./stage1.sh
+  - ./stage2.sh

Dockerfile

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+# Specify the base image to build from as a --build-arg.
+ARG BASE_IMAGE
+FROM $BASE_IMAGE
+
+# The docker build process is noninteractive
+ARG DEBIAN_FRONTEND=noninteractive
+
+# Run the install process using the provided script (chosen using --build-arg)
+ARG DOCKER_SCRIPT
+COPY docker_scripts/ /scripts/
+RUN /scripts/${DOCKER_SCRIPT}

VERSION

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+0.1.0

common.sh

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+#!/usr/bin/env bash
+
+# Get the version from the version file.
+export VERSION=$(cat VERSION)
+
+# Use this repository
+export DOCKER_REPO=curlbuildimages
+
+
+# Simple function which uses docker to build images.
+build_image()
+{
+  TAG=$1
+  BASE_IMAGE=$2
+  DOCKER_SCRIPT=$3
+
+  echo "Building ${TAG}:${VERSION} from ${BASE_IMAGE}"
+
+  docker build --build-arg BASE_IMAGE=${BASE_IMAGE} \
+               --build-arg DOCKER_SCRIPT=${DOCKER_SCRIPT} \
+               -t ${DOCKER_REPO}/${TAG}:${VERSION}  \
+               .
+}
+
+# Simple wrapper function which adds the REPOSITORY and VERSION to the given
+# BASE_IMAGE, then builds.
+build_image_versioned()
+{
+  TAG=$1
+  BASE_IMAGE=$2
+  DOCKER_SCRIPT=$3
+
+  build_image ${TAG} ${DOCKER_REPO}/${BASE_IMAGE}:${VERSION} ${DOCKER_SCRIPT}
+}

docker_scripts/install_base_tools.sh

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+#!/usr/bin/env bash
+
+# Print out debug info and fail if a sub-step fails
+set -exuo pipefail
+
+# Install the tool needed for `add-apt-repository`.
+apt-get -y update
+apt-get -y install software-properties-common

docker_scripts/install_clang7.sh

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+#!/usr/bin/env bash
+
+# Print out debug info and fail if a sub-step fails
+set -exuo pipefail
+
+# Install the necessary repositories for clang:
+# - llvm-toolchain-xenial-7
+
+# Use wget to download the key as we're building curl...
+apt-get install -y wget
+wget http://apt.llvm.org/llvm-snapshot.gpg.key
+apt-key add llvm-snapshot.gpg.key
+add-apt-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-7 main"
+
+# Install clang7
+apt-get -y update
+apt-get -y install clang-7
+
+# Install clang-7 as the standard cc and clang++-7 as the standard c++
+update-alternatives --install /usr/bin/clang clang /usr/bin/clang-7 10
+update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-7 10
+update-alternatives --install /usr/bin/cc cc /usr/bin/clang 30
+update-alternatives --set cc /usr/bin/clang
+update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++ 30
+update-alternatives --set c++ /usr/bin/clang++

docker_scripts/install_gcc8.sh

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+#!/usr/bin/env bash
+
+# Print out debug info and fail if a sub-step fails
+set -exuo pipefail
+
+# Install the necessary repositories for newer gccs:
+# - ubuntu-toolchain-r-test
+add-apt-repository ppa:ubuntu-toolchain-r/test
+
+# Install gcc-8
+apt-get -y update
+apt-get -y install gcc-8 g++-8
+
+# Install gcc-8 as the standard cc and g++-8 as the standard c++
+update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 10
+update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-8 10
+update-alternatives --install /usr/bin/cc cc /usr/bin/gcc 30
+update-alternatives --set cc /usr/bin/gcc
+update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++ 30
+update-alternatives --set c++ /usr/bin/g++

stage1.sh

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+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+. common.sh
+
+# Build stage 1. Stage 1 consists of the root base image with some common tools installed.
+echo "Building stage 1 (version ${VERSION})"
+
+# Build the root base image from Xenial
+build_image base_image ubuntu:xenial-20190515 install_base_tools.sh

stage2.sh

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+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+. common.sh
+
+# Build stage 2. Stage 2 produces images with gcc-8 and clang-7 installed.
+echo "Building stage 2 (version ${VERSION})"
+
+# Build gcc-8. Depends on `base_image` from stage1
+build_image_versioned base_gcc8 base_image install_gcc8.sh
+
+# Build clang-7. Depends on `base_image` from stage1
+build_image_versioned base_clang7 base_image install_clang7.sh