Update deployment Dockerfile

- This build will change how the website is run on the server
- The goal is to make deployment identical to local development (even if
you don't run in a Docker container)

.dockerignore

@@ -3,4 +3,3 @@
 _site
 README.md
 Dockerfile
-docker-build.sh

Dockerfile

@@ -1,10 +1,20 @@
-FROM jekyll/jekyll:3.0.2
+FROM ruby:2.5.1-alpine
 MAINTAINER Scott Numamoto <scott.numamoto@pioneers.berkeley.edu>
 
+# Add the enclosing dir to the image at /srv/jekyll
 ADD . /srv/jekyll
-VOLUME /srv/jekyll
 
+# Use this folder as dir we will work from
+WORKDIR /srv/jekyll
+
+# Install dependencies
+CMD bundle install
+
+# Build the website
+CMD bundle exec jekyll build
+
+# Expose port 4000, the port Jekyll exposes by default
 EXPOSE 4000
 
-ENTRYPOINT ["jekyll"]
-CMD ["serve"]
+# Serve the website when we run the image
+ENTRYPOINT ["bundle exec jekyll serve"]