Using Docker for Rouge development

Docker can be used to avoid having to install Ruby and all the dependencies locally.

Clone the project first, and navigate into your clone:

$ git clone https://github.com/jneen/rouge.git
$ cd rouge

Install the dependencies

$ docker run -t -v $PWD:/app -v /tmp/vendor:/vendor -w /app -e BUNDLE_PATH=/vendor ruby bundle

Let's unpack this:

docker run -it: Run an command in a new container. -t is not strictly necessary but allows nice colors in the output
-v $PWD:app: That maps the current folder into the /app path within the container. Used in conjunction with -w (see below), that allows the container to run as if it were inside this directory
-v /tmp/vendor:/vendor: That maps an arbitrary vendor folder into the /vendor path within the container. This is to persist the installed dependencies across Docker commands, otherwise you would have to re-install them every time as containers are ephemeral by nature
-e BUNDLE_PATH=/vendor: That sets an environment variable inside the container that tells Bundler to lookup the dependencies from the /vendor path (that we've mapped to our host machine with the previous line)
ruby: Tells it which image to use for the container. Ruby is part of the official library of "base" Docker images
bundle is the command to run within the container

Just replace the bundle command with rake:

$ docker run -t -v $PWD:/app -v /tmp/vendor:/vendor -w /app -e BUNDLE_PATH=/vendor ruby rake

$ docker run -t -v $PWD:/app -v /tmp/vendor:/vendor -w /app -e BUNDLE_PATH=/vendor -p 9292:9292 ruby bundle exec rackup --host 0.0.0.0

The additional command line flags are:

-p 9292:9292: Expose the port 9292 of the container to the host, on the same port
bundle exec rackup --host 0.0.0.0: Run Rack, and ask it to listen on all addresses. Without this it will only listen on the localhost of the container that won't be available from the host machine

You should be able to visit http://localhost:9292/ at this point.