Score App

A Phoenix API app, with a single endpoint that returns at max 2 users with more points than a random value.

Elixir 1.12.2	Erlang 24.0	Postgres 13.3

• Here you can track the Issues's list from this Repo.
• To understand my development process you can read the past Pull Requests or the Technical Decisions's file.
• Here you can access this Project Demo(Temporarily unavailable) deployed with Gigalixir

If you have any question or suggestion feel free to reach me out by E-mail or Twitter, let's learn together :)

Getting Started

Business Logic Explained

The business logic has been explained in details and breaks down into the Issues's list, but here is a summary of it:

• mix ecto.setup will create a Users table with 3 columns: id, points (any number between 0..100) and timestamp. This should generate 1_000_000 user seeds, each with 0 points.
• When the app starts, a GenServer should be launched which will:
  • Have 2 elements as state: random (0..100) max_number and a timestamp (defaults to nil).
  • Run every minute and when it runs:
    • Should update every user's points in the database (using a random number generator [0-100] for each) and refresh max_number with a new random number.
  • Should accept a handle_call that:
    • Queries the database for all users with more points than max_number but only retrieve a max of 2 users, updates timestamp with the current timestamp and returns the users just retrieved, as well as the timestamp of the previous handle_call.
• The app should also have a single endpoint, root /:

• This can be handled by an action which will call the previously mentioned GenServer and return the result, example:
  • GET localhost:4000/

     {
       'users': [{id: 15, points: 42}, {id: 42, points: 45}],
       'timestamp': `2021-08-08 12:30:15`
     }

Environment setup

Score App have the following dependencies:

Erlang, Elixir, Postgres and Docker (optional)

To prepare your environment, I made this Installation Guide:

• How to install dependencies

Running

After the environment setup (if you haven't cloned Repo yet), clone the Repo and access the project folder created:

git clone git@github.com:JulianaHelena5/score.git
cd score

• Database Setup

  Check the config/dev.exs and config/test.exs files and make sure that the settings match your local Postgres environment variables, example:

   # Configure your database - config/dev.exs
   config :score, Score.Repo,
     username: System.get_env("PGUSER", "postgres"),
     password: System.get_env("PGPASSWORD", "postgres"),
     database: System.get_env("PGDATABASE", "score_dev"),
     hostname: System.get_env("PGHOST", "localhost")

Now, we have two ways to run it:

• Running with Docker

  Run docker-compose commands:

docker-compose build
docker-compose run --rm phx mix ecto.setup
docker-compose up -d

• Running without Docker

  Run the following commands:

mix deps.get
mix ecto.setup
mix phx.server

In both ways, access the app through: http://localhost:4000/

Testing

To run the Tests you should only execute:

mix test

If you face any error please check the configuration of the config/test.exsfile explained at the Database Setup step.

Test Coverage

Run this line to check the Test coverage report:

mix coveralls #Show coverage
mix coveralls.detail #Show coverage with details by file

CI/CD

This project is using Github Actions and is being deployed to Gigalixir. (Temporarily unavailable)

You can check the Elixir CI and Gigalixir - Deploy files to understand the flow and also check the history of runs from all workflows.

Project Standards

In this step you'll find some choices I made to try to improve the Project Quality:

• To format the code I'm using mix format:

  mix format

• As a static code analysis tool I'm using Credo:

  mix credo

"It can show you refactoring opportunities in your code, complex code fragments, warn you about common mistakes, show inconsistencies in your naming scheme and - if needed - help you enforce a desired coding style" (Credo's Readme).

• Configured GitHub hooks to prevent unformatted code or failing Tests from being pushed. You can check the pre-push and pre-commit files here.

• To help with the quality of code changes description I added this Pull Request Template.

Future: to infinity and beyond

Keep moving forward :)

• Fix Gigalixir database access.
• Improve GenServer tests.
• Increase test coverage.
• Study a better way to schedule the GenServer call if needed.
• Metrics and monitoring.

Do you have any suggestion? Send me, please!

Learn more

• Official website: https://www.phoenixframework.org/
• Guides: https://hexdocs.pm/phoenix/overview.html
• Docs: https://hexdocs.pm/phoenix
• Forum: https://elixirforum.com/c/phoenix-forum
• Source: https://github.com/phoenixframework/phoenix