Como migrei um ETL legado para AWS Lambda gastando R$ 3/mês

import json
import os
import logging
from datetime import datetime, timedelta

import firebirdsql
import boto3
import urllib.request

logger = logging.getLogger()
logger.setLevel(logging.INFO)

sns = boto3.client("sns")
sm = boto3.client("secretsmanager")

SNS_TOPIC_ARN = os.environ["SNS_TOPIC_ARN"]
SECRET_NAME = os.environ["SECRET_NAME"]
FB_DATABASE = os.environ["FB_DATABASE"]

BCB_URL = (
    "https://olinda.bcb.gov.br/olinda/servico/PTAX/versao/v1/"
    "odata/CotacaoDolarPeriodo(dataInicial=@di,dataFinalCotacao=@df)"
    "?@di='{start}'&@df='{end}'"
    "&$format=json&$orderby=dataHoraCotacao%20asc"
)


def lambda_handler(event, context):
    """Pipeline PTAX: 7 passos sequenciais."""

    # 1. Buscar credenciais no Secrets Manager
    secret = json.loads(
        sm.get_secret_value(SecretId=SECRET_NAME)["SecretString"]
    )
    logger.info("Credenciais obtidas do Secrets Manager")

    # 2. Conectar no Firebird
    conn = firebirdsql.connect(
        host=secret["host"],
        port=int(secret["port"]),
        database=FB_DATABASE,
        user=secret["user"],
        password=secret["password"],
        charset="UTF8",
    )
    cur = conn.cursor()
    logger.info("Conectado ao Firebird")

    # 3. Obter estado atual (ultima data + proximo ID)
    cur.execute("SELECT MAX(DATA) FROM COTACAO_DOLAR")
    last_date = cur.fetchone()[0]

    cur.execute("SELECT MAX(ID) FROM COTACAO_DOLAR")
    max_id = cur.fetchone()[0] or 0

    start = (last_date + timedelta(days=1)).strftime("%m-%d-%Y") if last_date else "01-01-2024"
    end = datetime.now().strftime("%m-%d-%Y")
    logger.info(f"Janela dinamica: {start} ate {end}")

    # 4. Consultar API PTAX do BCB
    url = BCB_URL.format(start=start, end=end)
    with urllib.request.urlopen(url, timeout=15) as resp:
        data = json.loads(resp.read().decode())

    rows = data.get("value", [])
    logger.info(f"API retornou {len(rows)} cotacoes")

    # 5. Inserir novas cotacoes
    inserted = 0
    for row in rows:
        max_id += 1
        dt = datetime.strptime(
            row["dataHoraCotacao"][:10], "%Y-%m-%d"
        ).date()
        cur.execute(
            "INSERT INTO COTACAO_DOLAR (ID, DATA, COMPRA, VENDA) VALUES (?, ?, ?, ?)",
            (max_id, dt, row["cotacaoCompra"], row["cotacaoVenda"]),
        )
        inserted += 1

    conn.commit()
    cur.close()
    conn.close()
    logger.info(f"{inserted} cotacoes inseridas")

    # 6. Notificar via SNS
    msg = f"PTAX pipeline OK: {inserted} cotacoes inseridas ({start} a {end})"
    sns.publish(TopicArn=SNS_TOPIC_ARN, Subject="PTAX Pipeline", Message=msg)

    # 7. Retornar resultado
    return {
        "statusCode": 200,
        "body": json.dumps({
            "inserted": inserted,
            "window": {"start": start, "end": end},
        }),
    }

# ── Lambda Function ──────────────────────────────────────
resource "aws_lambda_function" "ptax" {
  function_name = "bcb-ptax-ingestion"
  runtime       = "python3.12"
  handler       = "lambda_handler.lambda_handler"
  architectures = ["arm64"]   # Graviton — 20% mais barato
  timeout       = 60
  memory_size   = 128

  filename         = data.archive_file.lambda_zip.output_path
  source_code_hash = data.archive_file.lambda_zip.output_base64sha256
  role             = aws_iam_role.lambda_role.arn

  vpc_config {
    subnet_ids         = var.private_subnet_ids
    security_group_ids = [data.aws_security_group.firebird.id]
  }

  environment {
    variables = {
      SECRET_NAME   = aws_secretsmanager_secret.firebird_creds.name
      FB_DATABASE   = var.firebird_database_path
      SNS_TOPIC_ARN = aws_sns_topic.ptax_alerts.arn
    }
  }

  layers = [aws_lambda_layer_version.deps.arn]

  depends_on = [aws_cloudwatch_log_group.ptax]
}

# ── EventBridge Scheduler ────────────────────────────────
resource "aws_scheduler_schedule" "ptax_daily" {
  name                = "ptax-daily-ingestion"
  schedule_expression = "cron(5 18 ? * MON-FRI *)"  # 18:05 BRT

  schedule_expression_timezone = "America/Sao_Paulo"

  flexible_time_window {
    mode = "OFF"
  }

  target {
    arn      = aws_lambda_function.ptax.arn
    role_arn = aws_iam_role.scheduler_role.arn

    retry_policy {
      maximum_retry_attempts = 2
    }
  }
}

{
  "statusCode": 200,
  "body": "{\"inserted\": 0, \"window\": {\"start\": \"03-31-2026\", \"end\": \"03-31-2026\"}}"
}