Add the ruby implementation as a showcase

[refs #911e345621a9]

Author: jfahrer

developing/webapp/Dockerfile

@@ -0,0 +1,9 @@
+FROM ruby:2.4.3-alpine
+
+WORKDIR /app
+
+RUN gem install sinatra
+
+COPY app.rb .
+
+CMD ["ruby", "app.rb"]

developing/webapp/app.rb

@@ -0,0 +1,8 @@
+require 'sinatra'
+
+set :bind, '0.0.0.0'
+set :port, 9494
+
+get '/' do
+  'Hello world!'
+end

developing/webapp/docker-compose.yml

@@ -0,0 +1,11 @@
+version: '3.3'
+
+services:
+  app:
+    image: jfahrer/webapp-ruby:latest
+    build:
+      context: .
+    volumes:
+      - .:/app
+    ports:
+      - 9494:9494