RealWorld Backend - .NET Modular Monolith

This is an implementation of the RealWorld API. It's written in .NET 6 and is a "modular monolith".

Building / Running

Everything is done via Batect. Just use ./batect --list-tasks to see everything you can do. You can build the app, run the app, run the unit tests, run the postman tests, and perform various linting and database operations.

All of these exact same batect tasks are run in GitHub Actions in order to implement the CI/CD pipeline.

Tech Stack

• Backend
  • .NET 6
  • MediatR
  • Dapper
  • Sqlite
  • Serilog
  • ArchUnit.NET
  • FluentMigrator
  • FluentValidation
  • xUnit
• DevOps
  • Docker
  • Batect
  • GitHub Actions
  • Renovate

Learning Goals

• Have a go at writing a modular monolith!
• Have a go at Clean / Hexagonal architecture
• Implement a full Continuous Deployment pipeline
• Learn ArchUnit.NET
• Learn GitHub Actions
• Learn Batect
• Learn Renovate
• Learn .NET Templating

Architecture

The logic is split into 3 separate domains:

• Users Domain
• Content Domain
• Feed Domain

Each domain has 3 projects associated with it:

• App.${ModuleName}.Domain
• App.${ModuleName}.Domain.Contracts
• App.${ModuleName}.Domain.Tests

Each App.${ModuleName}.Domain project contains a Setup/Module/${ModuleName}Module.cs which subclasses AbstractModule which implements IHostingStartup and provides a framework for loading all MediatR use cases in the module as well as setting up an IDbConnection to that modules database. Each module has it's own database which only it can access. Domain operations are split into commands, and queries and implemented via MediatR. Everything inside the domain project itself is marked as internal so that nothing else can access its logic or database directly. The API project contains a direct project reference to each module and is loaded by including the assembly name in the comma seperated list in HostingStartupAssembliesKey.

Each App.${ModuleName}.Domain.Contracts project contains all of the contracts of the domain operations. Everything in the contracts project is marked as public. This represents the strict boundary through which other modules can interact with the domain.

Each App.${ModuleName}.Domain.Tests project contains one test class per domain operation. All testing is done at the contracts boundary via MediatR.

ArchUnit.NET is used to enforce that each module conform to the conventions a module is expected to follow in terms of folder structures, namespaces, access modifiers, and naming conventions.

Domain modules can listen for events that happen in other domain modules and perform any processing accordingly. Each ${OperationName}CommandResult implements INotification which a MediatR pipeline behavior uses to publish these events. Domain modules interested in a particular operation simply implement an INotificationHandler<${OperationName}CommandResult> under Infrastructure/EventListeners/${OperationName}CommandResultListener.cs

A set of .NET templates are provided for quickly creating both new domain modules (AppTemplates/Module/generate_module.sh) and new domain operations (AppTemplates/Operation/generate_operation_command.sh / AppTemplates/Operation/generate_operation_query.sh).