We have some customer records in a text file (customers.txt) -- one customer per line, JSON lines formatted. We want to invite any customer within 100km of our Dublin office for some food and drinks on us. Write a program that will read the full list of customers and output the names and user ids of matching customers (within 100km), sorted by User ID (ascending).

• You can use the first formula from this Wikipedia article to calculate distance. Don't forget, you'll need to convert degrees to radians.
• The GPS coordinates for our Dublin office are 53.339428, -6.257664.
• You can find the Customer list here.

• Docker

$ git clone 'https://github.com/renington/invite_customers.git'
$ cd invite_customers
$ docker-compose up --build

docker-compose run --rm app ruby app.rb

docker-compose run --rm app rspec

• Docker - Development environment
• Ruby - The language
• Bundler - Dependency Management
• RSPEC - The Test tool