Rollify

Introduction

Rollify is a web applicaiton manage your dice rolls when you play online tabletop role games with your friends.

It exposes a REST API for this. Main features:

• Create Rooms
• Throw dice rolls in the room that will be received by all the connected users.
• Dice roll history for the room (by date, user...)
• No registration required (only a room link needs to be shared).
• Compatible dice: d4, d6, d8, d10, d12, d20.
• Different dice combinations.
• Open source
• Available online in https://rollify.app

App

This is the rollify backend and frontend (A monolith), it has all the logic, it exposes a REST API to integrate with and also a very simple and clean frontend using HTMX and PicoCSS.

API

You can chek the API docs here. You can use the Swagger editor online and import that URL to have readable docs.

Where is running Rollify

Is running on my personal Kubernetes tiny cluster, depending on the usage of the app, I'll find a bigger home for Rollify.

Architecture

Storage

Rollify supports multiple storage types

Memory

By default it will run with memory based storage, this is useful for development, because you don't need to set up a MySQL database (although if you are developing MySQL storage features you will need to use this storage).

If you want to run a cheap rollify for you and your friends with ephemeral dice rolls, you can run this with a single instance and will do the job.

MySQL

You have the schema in schema.

Events

Rollify uses websockets to notify the clients using events, for example when there is a new dice roll.

Memory

By default it will run with a memory based event system, this is useful for development, because you don't need to set up a NATS server.

As with the memory database, this can be used for cheap rollify deployments that only have one instance and don't need to communicate with other rollify instances.

NATS

In order that all the users connected to the different Rollify instances receive the events, the publisher needs to notify all the instances, this is done with a NATS pubsub system.

Scalability

At this moment Rollify scales horizontally, for this you will need:

• MySQL storage for the database.
• NATS message system for the events delivery.

Metrics

It has Prometheus metrics for almost all the internal components on the :8081/metrics endpoint:

• HTTP API.
• Application services (domain logic).
• Storage.
• Dice roller (this important we want evenlly distributed dice rolls).
• Event stream (events, websockets...).

Development

Download the source code and run, this should be enough for most of the cases:

go run ./cmd/rollify/ --development --debug

You can use:

• make test: Runs all the tests.
• make check: Checks the source code.
• make gen: Generates everything required by the app (e.g mocks).