UpdatedAug 5, 2026

Laravel Service Container

Question Variations

"When do you create a service provider binding?"
"How do you inject an interface implementation?"
"When is a singleton unsafe in a long-running worker?"

Why This Is Asked

The service container reveals whether a candidate can design decoupled Laravel components and control object lifecycles.

Key Concepts

The container resolves constructor dependencies automatically.
Service providers register bindings during application bootstrap.
Interfaces can bind to concrete implementations.
Singleton bindings need safe lifecycle and state assumptions.

Question Variations

“When do you create a service provider binding?”
“How do you inject an interface implementation?”
“When is a singleton unsafe in a long-running worker?”

Answers by Technology

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Expected Answer (Laravel 13 / PHP 8.3+)

Laravel’s service container resolves constructor dependencies and lets applications bind interfaces to implementations. Register application-level bindings in a service provider; use a singleton only when the object is safe to share for the relevant worker lifecycle. Constructor injection keeps dependencies explicit and easily replaceable in tests.

Why It Matters

Container bindings decouple business logic from infrastructure and keep tests focused.

Code Example

final class BillingServiceProvider extends ServiceProvider
{
    public function register(): void
    {
        $this->app->bind(TaxCalculator::class, StandardTaxCalculator::class);
    }
}

Common Mistakes

Using global facades for every dependency: Hidden dependencies make tests and design harder.
Making mutable services singletons: State can leak across long-lived worker requests.

Follow-up Questions

When use a singleton binding? (Answer: For safe shared objects such as stateless clients.)
Where register bindings? (Answer: In a service provider.)