FastAPI com Docker na VPS

# Dockerfile
FROM python:3.12-slim

WORKDIR /app

# Instalar dependências do sistema (mínimo necessário)
RUN apt-get update && apt-get install -y --no-install-recommends \
    gcc \
    libpq-dev \
    && rm -rf /var/lib/apt/lists/*

# Copiar e instalar requirements antes do código (melhor cache)
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copiar código da aplicação
COPY . .

# Usuário não-root
RUN useradd -m appuser && chown -R appuser:appuser /app
USER appuser

EXPOSE 8000

# Gunicorn com workers Uvicorn (produção)
CMD ["gunicorn", "main:app", \
     "--worker-class", "uvicorn.workers.UvicornWorker", \
     "--workers", "4", \
     "--bind", "0.0.0.0:8000", \
     "--access-logfile", "-", \
     "--error-logfile", "-"]

# requirements.txt
fastapi==0.115.0
uvicorn[standard]==0.32.0
gunicorn==23.0.0
sqlalchemy==2.0.36
asyncpg==0.30.0       # driver async para PostgreSQL
alembic==1.14.0       # migrações de banco
python-dotenv==1.0.1
pydantic-settings==2.6.0

# main.py
from fastapi import FastAPI
from contextlib import asynccontextmanager
from app.database import engine
from app.routers import users, items

@asynccontextmanager
async def lifespan(app: FastAPI):
    # Startup
    print("Aplicação iniciando...")
    yield
    # Shutdown
    await engine.dispose()
    print("Aplicação encerrando...")

app = FastAPI(
    title="Minha API",
    version="1.0.0",
    lifespan=lifespan,
    # Desabilitar docs em produção (opcional)
    docs_url=None if os.getenv("ENV") == "production" else "/docs",
)

app.include_router(users.router, prefix="/users", tags=["users"])
app.include_router(items.router, prefix="/items", tags=["items"])

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

services:
  api:
    build: .
    restart: always
    env_file: .env
    environment:
      DATABASE_URL: postgresql+asyncpg://${DB_USER}:${DB_PASS}@postgres:5432/${DB_NAME}
    depends_on:
      postgres:
        condition: service_healthy
    healthcheck:
      test: ["CMD", "python", "-c",
             "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')"]
      interval: 30s
      timeout: 10s
      retries: 3
    networks:
      - app_net

  postgres:
    image: postgres:16-alpine
    restart: always
    environment:
      POSTGRES_USER: ${DB_USER}
      POSTGRES_PASSWORD: ${DB_PASS}
      POSTGRES_DB: ${DB_NAME}
    volumes:
      - pg_data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${DB_USER}"]
      interval: 10s
      retries: 5
    networks:
      - app_net

  nginx:
    image: nginx:alpine
    restart: always
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro
      - certbot_conf:/etc/letsencrypt
      - certbot_www:/var/www/certbot
    depends_on:
      - api
    networks:
      - app_net

volumes:
  pg_data:
  certbot_conf:
  certbot_www:

networks:
  app_net:

# Inicializar Alembic (uma vez)
alembic init migrations

# alembic.ini — definir URL do banco
# sqlalchemy.url = %(DATABASE_URL)s

# migrations/env.py — importar models para detectar mudanças
from app.models import Base
target_metadata = Base.metadata

# Gerar migração a partir dos models
alembic revision --autogenerate -m "create users table"

# Aplicar migrações pendentes
alembic upgrade head

# No deploy (via docker-compose exec):
docker compose exec api alembic upgrade head

# Ver histórico de migrações
docker compose exec api alembic history

# Rollback de uma migração
docker compose exec api alembic downgrade -1

# app/config.py
from pydantic_settings import BaseSettings

class Settings(BaseSettings):
    database_url: str
    secret_key: str
    debug: bool = False
    allowed_origins: list[str] = ["https://seudominio.com.br"]
    max_connections: int = 10

    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"

settings = Settings()

# .env (não commitado no git)
DATABASE_URL=postgresql+asyncpg://user:pass@postgres:5432/db
SECRET_KEY=sua_chave_secreta_longa
DEBUG=false
ALLOWED_ORIGINS=["https://api.seudominio.com.br"]