The purpose of a link shortener is to reduce url length by converting a full url to smaller footprint. This smaller footprint is easier to share in social media and can also include third-party analytics.

There are two common ways to shorten links:

1. Hashing or encoding the full url using a algorithm like base64 or MD5
2. Create a random, unique link id and saving the link id for use during link resolution

In both cases, a route will need to handle the translation from shortened link to full link.

I chose to create a link id for a few reasons:

• The request had specific length and character requirements for the shortened url and I did not want to create a special hashing function
• Hashing has a small chance of two urls colliding (very unlikely but possible with shorter lengths)
• Creating a link id allows for very small urls -- the algorithm I chose can be modified to shrink links further than the requested 6 characters
• Storing the link information in a database allows us to extend the shortener to other useful features
  • Expiring old links
  • Tracking analytics data on link creation
  • Allowing short links with specific words or characters

The easiest form of link resolution is to return a HTTP 302 response. An alternative would be using an HTML redirect for browsers that accept HTML and only use a 302 response for non-HTML browsers but there are few reasons to do so.

To run the project you will need access to a DynamoDB table and the appropriate AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY. You can add them as envrionment variables or to a Docker compose override file. Tests run against DynamoDB Local but still require AWS key/secret due to how the AWS SDK works.

To start the api:

• docker-compose build api
• docker-compose up api

To run tests:

• docker-compose build test
• docker-compose up test