UrlShortener

Simple Url shortener in Elixir

Installation / Setup

• For dev environments, it is recommended to use docker-compose, that references to a Postgres image, without requiring to install or use any existing database, leaving to docker to resolve this: docker-compose up sets up the environment with application on port 4000 and db on 5432 docker-compose down kills containers and cleans generated data (does not delete images).

• For production environments, please point to a real database and change prod.exs config, then build and run the docker image.

• To run tests, you need to set MIX_ENV environment variable to test, and then run mix test. If using docker-compose the command should be run inside the url_shortener container. Example already setting the env var for this execution:

MIX_ENV=test mix test

Business rules implemented

• RESTful endpoint to generate a short hash representing a URL in the same API
• Unique shortened url for each long URL
• Shortened url expiration in 1 month without interaction
• Dynamic parameters for existing and new parameters
• All requests are tracked and all request headers are stored related to a single link, in a queryable fashion for analytics purpose.

Architecture

• One POST endpoint to create the URL and reply with a JSON containing the short key hash: /api/generate_short_url
• One generic GET endpoint to access the long url through the hash created on POST endpoint /SHORT_HASH
• Each POST of a new long url generates a new line in urls table, with a new short hash and validity to one month later. If the hash already exists it only updates the validity and returns the already created hash.
• Each GET of an existing short hash will generate a new registry in url_metadata table, associated by the urls_id, so in order to query by a long url, for example, it is necessary to JOIN the two.
• The metadata (request headers) was saved as a json map (jsonb structure in postgres, map in elixir), this is to allow flexibility in the request headers, as they may change a lot depending on the client.
• Example query for the URL http://google.com/ see all the metadata generated: select metadata from url_metadata where full_url = 'http://google.com/'
• Example query to select all requests hitting localhost, querying the JSON inside the table: select * from url_metadata WHERE metadata @> '{"host": "localhost:4000"}'