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[Home](https://www.msaied.com/public) 2. / 3. [Articles](https://www.msaied.com/public/articles) 4. / 5. Modular Monolith in Laravel: Enforcing Bounded Contexts Without a Microservices Tax Modular Monolith in Laravel: Enforcing Bounded Contexts Without a Microservices Tax ==================================================================================== Learn how to carve a Laravel application into cohesive bounded contexts using modules, internal contracts, and dependency rules — without splitting into microservices or reaching for a DDD framework. ![](https://cdn.msaied.com/01M22N44A70A5MC2S599JP0MPH.webp) [Mohamed Said](https://www.msaied.com/public#person) Published 6 Jul 2026 · Updated 6 Jul 2026 · 3 min read ShareCopy linkCopied ![Modular Monolith in Laravel: Enforcing Bounded Contexts Without a Microservices Tax](https://cdn.msaied.com/380/024b5513124d6a6f3f0588cb3f6554c3.png) On this page +1. [Why a Modular Monolith?](#why-a-modular-monolith) 2. [Module Structure](#module-structure) 3. [Internal Contracts: The Boundary Enforcement Mechanism](#internal-contracts-the-boundary-enforcement-mechanism) 4. [Enforcing the Rules with Deptrac](#enforcing-the-rules-with-deptrac) 5. [Cross-Module Events Instead of Direct Calls](#cross-module-events-instead-of-direct-calls) 6. [Shared Kernel](#shared-kernel) 7. [Key Takeaways](#key-takeaways) Why a Modular Monolith? ----------------------- Microservices solve distribution problems you probably don't have yet. A modular monolith gives you the same conceptual separation — bounded contexts, explicit contracts, isolated domain logic — while keeping a single deployable, a single database transaction scope, and zero network overhead between modules. The goal is not folder organisation for its own sake. It is **preventing accidental coupling** so that the Billing team can refactor invoicing without breaking the Shipping team's code. --- Module Structure ---------------- Each bounded context lives under `app/Modules/{Context}/`. The internal layout mirrors a mini-application: ```php app/Modules/ Billing/ Actions/ Data/ # DTOs, value objects Domain/ # Eloquent models, domain services Http/ # Controllers, requests, resources Infrastructure/ # Repositories, external adapters Providers/ BillingServiceProvider.php routes.php Shipping/ ... ``` Each module registers itself via its own service provider, which is loaded from `bootstrap/providers.php` (Laravel 11+): ```php // bootstrap/providers.php return [ App\Modules\Billing\Providers\BillingServiceProvider::class, App\Modules\Shipping\Providers\ShippingServiceProvider::class, ]; ``` ```php // app/Modules/Billing/Providers/BillingServiceProvider.php class BillingServiceProvider extends ServiceProvider { public function boot(): void { $this->loadRoutesFrom(__DIR__ . '/../routes.php'); $this->loadMigrationsFrom(__DIR__ . '/../Infrastructure/Migrations'); } public function register(): void { $this->app->bind( \App\Modules\Billing\Domain\Contracts\InvoiceRepository::class, \App\Modules\Billing\Infrastructure\EloquentInvoiceRepository::class, ); } } ``` --- Internal Contracts: The Boundary Enforcement Mechanism ------------------------------------------------------ Modules must never import each other's internal classes directly. Instead, each module exposes a **public API interface** in a `Contracts` namespace: ```php // app/Modules/Billing/Contracts/BillingModuleInterface.php namespace App\Modules\Billing\Contracts; use App\Modules\Billing\Data\InvoiceData; interface BillingModuleInterface { public function issueInvoice(int $orderId, int $customerId): InvoiceData; public function getOutstandingBalance(int $customerId): Money; } ``` Shipping resolves this interface through the container — it never touches `Billing\Domain\` directly: ```php // app/Modules/Shipping/Actions/DispatchOrder.php class DispatchOrder { public function __construct( private readonly BillingModuleInterface $billing, ) {} public function handle(Order $order): void { $balance = $this->billing->getOutstandingBalance($order->customer_id); if ($balance->isNegative()) { throw new OutstandingBalanceException(); } // dispatch logic ... } } ``` --- Enforcing the Rules with Deptrac -------------------------------- Folder conventions are worthless without tooling. [Deptrac](https://github.com/qossmic/deptrac) analyses static imports and fails CI when a module reaches across a boundary: ```yaml # deptrac.yaml deptrac: paths: - app/Modules layers: - name: Billing collectors: - type: directory value: app/Modules/Billing/ - name: Shipping collectors: - type: directory value: app/Modules/Shipping/ ruleset: Shipping: - Billing # Shipping may only use Billing's public Contracts Billing: ~ ``` Run `./vendor/bin/deptrac analyse` in CI. Any direct import of `Billing\Domain\` from `Shipping\` becomes a build failure. --- Cross-Module Events Instead of Direct Calls ------------------------------------------- For truly decoupled side-effects, prefer domain events over direct method calls: ```php // Billing fires: event(new InvoicePaid($invoiceId, $customerId, $amount)); // Shipping listens in its own EventServiceProvider: Event::listen(InvoicePaid::class, ReleaseHeldShipments::class); ``` The event class lives in a shared `app/Events/` namespace (or a dedicated `app/Shared/` module) so neither context owns it. --- Shared Kernel ------------- Some primitives — `Money`, `Address`, `UserId` — are used everywhere. Place them in `app/Shared/` and treat that namespace as a read-only dependency for all modules. No module writes back to Shared. --- Key Takeaways ------------- - **One service provider per module** keeps registration isolated and explicit. - **Public contract interfaces** are the only surface other modules may depend on. - **Deptrac in CI** turns architectural rules into hard failures, not guidelines. - **Domain events** decouple side-effects without requiring a message broker. - **Shared kernel** is small and stable; resist the urge to dump utilities there. - [laravel](https://www.msaied.com/public/articles?search=laravel) - [architecture](https://www.msaied.com/public/articles?search=architecture) - [ddd](https://www.msaied.com/public/articles?search=ddd) - [modular-monolith](https://www.msaied.com/public/articles?search=modular-monolith) Frequently asked questions --------------------------- Do I need separate databases per module?No. A modular monolith shares one database. The boundary is in code, not infrastructure. You can extract a module to a microservice later if needed, but separate databases are not a prerequisite. How do I handle shared Eloquent models that multiple modules need?Place truly shared models (e.g. User) in a Shared or Core module. Each consuming module accesses them through that shared namespace, never by reaching into another module's Domain folder. Is Deptrac the only option for enforcing boundaries?PHPArkitect is a PHP-native alternative with a fluent API. Both integrate well with GitHub Actions or any CI pipeline and serve the same purpose: turning architectural conventions into automated checks. ![Mohamed Said](https://cdn.msaied.com/01M22N44A70A5MC2S599JP0MPH.webp)About the author ---------------- [Mohamed Said](https://www.msaied.com/public#person)Senior Backend Engineer specializing in Laravel, scalable SaaS platforms, APIs, and cloud infrastructure. I build secure, high-performance web applications that help businesses grow. [About](https://www.msaied.com/public#about) [GitHub ↗](https://github.com/EG-Mohamed) [LinkedIn ↗](https://www.linkedin.com/in/msaiedm/) [WhatsApp ↗](https://wa.me/201094619204) [Email Address ↗](mailto:hello@msaied.com) [My CV ↗](https://drive.google.com/file/u/0/d/1MF20IPRJyzfy32mhEutjL5EpSls0w2Q8/view) [Previous articleDomain-Driven Design in Laravel: Value Objects, DTOs, and Actions Without Bloat](https://www.msaied.com/public/articles/domain-driven-design-in-laravel-value-objects-dtos-and-actions-without-bloat) [Next articleBuilding a Laravel Package: Service Providers, Auto-Discovery, and Config Merging](https://www.msaied.com/public/articles/building-a-laravel-package-service-providers-auto-discovery-and-config-merging-1) On this page ------------- 1. [Why a Modular Monolith?](#why-a-modular-monolith) 2. [Module Structure](#module-structure) 3. [Internal Contracts: The Boundary Enforcement Mechanism](#internal-contracts-the-boundary-enforcement-mechanism) 4. [Enforcing the Rules with Deptrac](#enforcing-the-rules-with-deptrac) 5. [Cross-Module Events Instead of Direct Calls](#cross-module-events-instead-of-direct-calls) 6. [Shared Kernel](#shared-kernel) 7. [Key Takeaways](#key-takeaways) ### Have a technical challenge? Tell me what you’re building. I reply within two working days. 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