Add support for building eBook with Docker

This change adds support for building the eBook with Docker. Supporting Docker means
that users who want to build the eBook do not have to install Ruby/Bundler/Calibre in their
environments.

I'm a Docker n00b, so if there's a better way to handle file permissions on the output, I'm all
ears.

Build tested on Linux. Outputs were fine.

There is also a change to the pandoc outputs. It seems the `+smart` extension is not supported for epub/html[0]
in their latest versions.

[0] - https://pandoc.org/MANUAL.html#extension-smart

Dockerfile

@@ -0,0 +1,16 @@
+FROM ubuntu:17.10
+
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    calibre \
+    pandoc \
+    ruby \
+    ruby-dev \
+    wget \
+    zlib1g-dev
+
+RUN gem install bundler --no-ri --no-rdoc
+
+COPY . /
+
+RUN bundle install

README.md

@@ -6,6 +6,10 @@ Generates a EPUB/MOBI for the Google SRE Book.
 
 Original sources are downloaded from https://landing.google.com/sre/
 
+# Build
+
+## macOS
+
 Review and run the `bootstrap.sh` script to generate the EPUB and MOBI files
 
 Requirements:
@@ -17,6 +21,16 @@ Requirements:
 - brew cask install calibre
 - brew install wget
 
+## Docker
+
+Requirements:
+
+- Docker
+
+```
+$ ./build_docker.sh
+```
+
 # Known Issues
 
 - Inline references are not handled in the best possible way

bootstrap.sh

@@ -13,6 +13,6 @@ bundle install
 ruby generate.rb
 
 pushd html/chapters
-pandoc -f html+smart -t epub+smart -o ../../google-sre.epub --epub-metadata=../../metadata.xml --epub-cover-image=../../cover.jpg sre.html
+pandoc -f html -t epub -o ../../google-sre.epub --epub-metadata=../../metadata.xml --epub-cover-image=../../cover.jpg sre.html
 popd
 ebook-convert google-sre.epub google-sre.mobi

build_docker.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+docker build -t google-sre-ebook .
+docker run -i --rm -v "$(pwd):/output" google-sre-ebook sh -s <<EOF
+./bootstrap.sh
+chown -v $(id -u):$(id -g) /google-sre.*
+mv -f /google-sre.* /output
+EOF