Deep Instruction · Phase 04
NestJS + Fastify — Request Lifecycle and Backend Architecture
Trace an HTTP request through Fastify and NestJS, then build modules/controllers/services with clear ownership.
01code-first02code-first03code-first04code-first05code-first06code-first07code-first08code-first
Bootstrap NestJS with Fastify
Understand the adapter boundary and what main.ts actually configures.
Modules as Composition Boundaries
Use modules to assemble related capabilities, not as arbitrary folders.
Controllers Own HTTP Translation
Keep request/response concerns here while pushing business rules deeper.
Services Own Application Behavior
Place orchestration and business rules behind a testable service boundary.
Pipes and Input Transformation
Validate/transform route inputs before application logic receives them.
Guards vs Interceptors vs Filters
Choose extension points by responsibility rather than because they all wrap requests.
Configuration and Graceful Shutdown
Treat runtime configuration and process lifecycle as production concerns.
Capstone: Tasks Module Through Fastify
Build a complete vertical slice from route to service with validation and error translation.