Serving scikit-learn models behind a FastAPI prediction API

import joblib
import pandas as pd
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI(title='Churn Prediction API')
model = joblib.load('artifacts/churn_pipeline.joblib')

class PredictionRequest(BaseModel):
    age: int
    income: float
    country: str
    plan_tier: str
    days_since_last_login: int

@app.get('/health')
def health():
    return {'status': 'ok'}

@app.post('/predict')
def predict(payload: PredictionRequest):
    frame = pd.DataFrame([payload.model_dump()])
    probability = float(model.predict_proba(frame)[:, 1][0])
    return {'churn_probability': probability, 'model_version': '2026-04-07'}