Added Docker for development

Dockerfile

@@ -0,0 +1,20 @@
+FROM ruby:2.3-alpine
+
+RUN apk add --update \
+  build-base \
+  libxml2-dev \
+  libxslt-dev \
+  nodejs
+
+# throw errors if Gemfile has been modified since Gemfile.lock
+RUN bundle config --global frozen 1
+
+WORKDIR /usr/src/app
+
+COPY Gemfile Gemfile.lock ./
+RUN bundle install
+
+COPY . .
+
+EXPOSE 4567
+CMD ["bundle", "exec", "middleman"]

README.md

@@ -19,6 +19,13 @@ This repository generates https://keepachangelog.com/.
 - `bundle install`
 - `bundle exec middleman` starts the local development server at http://localhost:4567
 
+### Docker
+
+- `git clone https://github.com/olivierlacan/keep-a-changelog.git`
+- `cd keep-a-changelog`
+- `docker build -t keep-a-changelog`
+- `docker run -p 4567:4567 keep-a-changelog` starts the docker development server and binds it at http://localhost:4567
+
 ### Deployment
 - `bundle exec rake publish` builds and pushes to the `gh-pages` branch