Widget Marketplace

A barebones marketplace for widgets.

Getting started

Clone the repo, and install dependencies.

Dependencies

The following should be install prior to running the project:

• elixir 1.11.2
• erlang 23.1.2
• Postgres 13 (11+ is probably fine)

There is a .tool-versions file for convineince in installing elixir and OTP via asdf.

asdf install

Postgres can be installed from the Postgres website

Run the following mix commands to bootstrap the project.

mix deps.get
mix ecto.create
mix ecto.migrate

Install NPM dependencies:

npm install --prefix assets/

Run the server with the following, the user interface is fully functional @ http://localhost:4000/

mix phx.server

Run the tests with the following:

mix test

Technology choices

• Elixir: My go to language for backend services.
• Postgres: I always ask "Why not postgres", and I think that answer should be compelling. Super mature, open source.
• Phoenix: Even for APIs, I find Phoenix to offer many of the features I would like to have.

Design decisions

• Utilized the repository pattern. I believe in most cases, we can use generalized functions for access to the datbase. Additionally, if their comes a time when the database needs to be swapped, or multiple adapters need to be utilized, the repository provides a seam that makes this much simpler.
• Tests are exclusively on the WidgetMarkeplace portion of the application. This is purely due to time. I wanted to test well where I needed to, and I just don't think that I had the time to test all actions on the front end. As it was, I spent ~8 hours on the entire project.
• Utilized the below dependencies for the reasons stated below.
• The WidgetMarkeplace has more documentation around the business logic.
• I chose to use integer for currency. The goal was to use the Money library, which is a bit similar to Authentication, generally suggested not to roll your own, and I didn't have the time to go down the "How do we store currency" rabbit hole. Would be next on the to-do.

Hex dependencies

argon2_elixir

This dependecy is need to ensure the hashing used is strong engouh to last in production for a few years.

ecto_sql

This dependecy is needed in order to use Ecto with the postgres database.

guardian

This dependecy is used for session tokens, and authorization.

jason

This dependecy is use to serialize/deserialize JSON.

phoenix

This is the base web framework.

phoenix_ecto

This is the plugin integrates phoenix and ecot

phoenix_html

This plugin provids many methods for creating html markup dynamically using helpers.

phoenix_live_dashboard

This plugin now ships with phoenix. Link is removed, but can still be visited at http://localhost:4000/dashboard

phoenix_live_reload

This dependecy is used for development, hot reloads code changes while the dev server is running.

postgrex

This dependecy is used by Ecto for the database adapter.

telemetry_metrics

This is the telemetry_metrics plugin, provides convineince methods for gathering metrics.

telemetry_poller

Allows to periodically collect measurements and dispatch them as Telemetry events. Ships with phoenix.

plug_cowboy

Plug adapter for the Erlang Cowboy web server.

credo

Configurable static code analyzer, used in development and CI.

mix_test_watch

Test watcher to smooth development.

dialyxir

Descrpancy analyzer for elixir. Used to check type signature if typespecs are provided, dead/unreachable code, unneeded test, etc. Used in CI.