Add a couple of questions on containers

Also, fixed some minor styling issues in random_question.py script.

exercises/devops/solutions/containerize_app.md

@@ -0,0 +1,54 @@
+## Containerize an Application
+
+1. Clone an open source project you would like to containerize. A couple of suggestions:
+
+```
+https://github.com/bregman-arie/node-hello-world
+https://github.com/bregman-arie/flask-hello-world
+```
+
+`git clone https://github.com/bregman-arie/node-hello-world`
+
+2. Write a Dockerfile you'll use for building an image of the application (you can use any base image you would like)
+
+```
+FROM alpine
+LABEL maintainer="your name/email"
+RUN apk add --update nodejs npm
+COPY . /src
+WORKDIR /src
+RUN npm install
+EXPOSE 3000
+ENTRYPOINT ["node", "./app.js"]
+```
+
+3. Build an image using the Dockerfile you've just wrote
+
+`docker image build -t web_app:latest .`
+
+4. Verify the image exists
+
+`docker image ls`
+
+5. [Optional] Push the image you've just built to a registry
+
+```
+docker login
+docker image tag web_app:latest <your username>/web_app:latest
+# Verify with "docker image ls"
+docker image push <your username>/web_app:latest
+```
+
+6. Run the application
+
+```
+docker container run -d -p 80:3000 web_app:latest
+```
+
+7. Verify the app is running
+
+```
+docker container ls
+docker logs <container ID/name>
+# In the browser, go to 127.0.0.1:80
+```