Flask API

Overview

Flask is a lightweight Python WSGI web framework (Werkzeug + Jinja2) widely used for REST APIs, ML model-serving microservices, internal tools, and webhook receivers. This section covers Flask end-to-end: architectural overview, benefits and when to reach for it, building REST APIs with validation and auth, runnable sample code for CRUD and ML serving, and production deployment with gunicorn, nginx, Docker, and Kubernetes.

Pages

• Flask — Overview — Micro-framework design, WSGI fundamentals, request/response lifecycle, core components, Flask vs FastAPI vs Django, ecosystem, limitations.
• Flask — Benefits & Utilization — Why Flask still matters: flexibility, extension ecosystem, production utilization patterns, honest “when not to use” guidance, performance characteristics.
• Flask — Building REST APIs — Routing, blueprints, validation (Marshmallow/Pydantic), error handling, HTTP status codes, JWT auth, CORS, rate limiting, pagination, OpenAPI with Flask-Smorest, testing.
• Flask — Sample Code — Runnable examples: CRUD with SQLAlchemy, JWT auth with refresh rotation, file upload, scikit-learn and PyTorch model serving, Celery async, Flask-SocketIO, cursor pagination, K8s probes, full app factory.
• Flask — Production Deployment — Gunicorn, nginx, multi-stage Docker, Kubernetes Deployment/HPA, 12-factor config, structured logging, Prometheus metrics, OpenTelemetry, security hardening, Alembic migrations, zero-downtime deploys.

Related

• FastAPI for REST APIs — Asynchronous counterpart to Flask; compare when you need native async and OpenAPI-by-default.
• Understanding and Implementing APIs — REST, SOAP, GraphQL, gRPC fundamentals.