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Rust code platform - part 1

Small project idea to have some fun with Rust and try to build something as close as possible to being production-ready. This project also aims to dabble a bit with the language on the web backend side.

Constraints

• Minimal requirements
• Observability

The idea I was thinking about is a simplified coding platform in the neetcode style. The system will be seeded with a set of problems, users can register, admin users can also upload new problems (although authentication and authorization may be out of scope for the time being). Problems can be run inside self-contained environments (think about Docker containers, maybe providing a subset of pre-built images for each programming language offered, C, C++, Python and Go can be a good starting point).

Tech stack

Rust is the chosen language for this project, I’m not really familiar yet with the current trends and best practices, last time I checked actix and sqlx were the backbone of any backend application. After some recognition work, this is what I came up with:

• Actix - REST APIs
• Postgres - Diesel or sqlx
• Prometheus
• Grafana

Axum and Pavex also look interesting, however it’s not the point of the project to explore different frameworks to achieve the same result, it’s the overall practicality of Rust for the web that I’d like to refresh. We’re probably gonna use Docker and docker-compose to run the entire environment locally in dev, it’s a convenient way to emulate a staging/prod environment without the hassle of deploying stuff to an Heroku dyno or any other cloud provider.

Data model

The main entity in the application is represented by the problems. They will include a title, a description and some metadata such as the category, the difficulty and a skeleton based on the language, something like

{
    title: "Two Sum",
    description: "Given an array of integers `nums` and an integer `target`, return the integers `i` and `j`  such that `nums[i] + nums[j] = target`..",
    categories: ["arrays"],
    difficulty: "easy",
    starting_snippets: {
        "c": "int *two_sum(int *nums, size_t len, int target) ..",
        "python": "def two_sum(nums, target)..."
    },
    solved: "false"
}

To start very simple they could be stored in a JSON or YAML static file on a filesystem, I prefer to store them in the DB to allow easier query capabilities and at a later stage, extensibility and upload of new problems. Every problem can have multiple solutions clearly, so that would be another table to be joined as a has_many relationship with the problem.

To cut short, a loosely detailed definition of the schemas we’re going to need:

• User
  • email: string
  • nickname: string
  • has_many(Problem)
• Problem
  • title: string
  • description: string
  • categories: list(string)
  • difficulty: string
  • starting_snippets: map
  • test_cases: list(string)
  • solved: boolean
  • editorial: map
  • has_many(Solution)
• Solution
  • description: string
  • snippet: string

Keeping things simple as a first draft, we can assume that the images repositories with various metadata (e.g. languages versions, OS etc) can be stored locally in a static JSON or YAML file.

APIs

It will be a pure REST application, no frontend at all, but it should provide all the required to be easily integrated in a JS app.

ASSUMPION we can start with a set of problems and editorial pre-seeded in the system, on a later stage we can decide to increment the functionalities and allow users roles, auth, and upload of new problems, contests maybe and notifications to subscribed users.

User management

Creation of a new user and retrieve of the user, probably with some sort of stats and solved problems etc.

• POST /v1/users
• GET /v1/users/:user_id

Problems management

Creation of a new problem, listing of all the problems, probably opt-in filters by category, difficulty and pagination etc; retrieve of a specific problem by ID. Definitely submission of a solution to any given problem and listing.

• GET /v1/problems/:problem_id
• GET /v1/problems
• POST /v1/problems/:problem_id

Authentication & RBAC

TBD