A Node JS Express application that reads the user input (number) and checks to see if its a non-negative integer or not. A docker image for this is available here - https://hub.docker.com/r/zeemarsh/non-negative-integer
Because of how light weight this application is - this tech stack feels like the ideal approach for running a lightweight container.
npm install will install all the required node_modules
node index.js will run the application on port 80