In this section, you're going to deploy the Todo API to Heroku so anybody with the URL can access these routes, adding and fetching Todo items. Now, before we can push it to Heroku, there are quite a few things we need to change, small tweaks to get it ready for the Heroku servers. One of the bigger tweaks is going to be to set up a real MongoDB database because currently we use a localhost database and this is not going to be available once we get our app on Heroku.
To kick things off we're going to move into the server file and set up the app variable to use the environment port variable that Heroku is going to set, which we did in the previous section when we deployed to Heroku. If you remember, what we did was we created a variable called port and we set that equal to process.env.PORT. This is the variable that may or may not be set...
