Gerenciamento de Orçamento de Erro

from datetime import datetime, timedelta

def calculate_error_budget(slo_target: float, window_days: int, total_requests: int, failed_requests: int):
    """Calculate remaining error budget."""
    budget_fraction = 1 - slo_target  # e.g., 0.001 for 99.9%
    total_allowed_failures = total_requests * budget_fraction
    remaining_failures = total_allowed_failures - failed_requests
    budget_remaining_pct = (remaining_failures / total_allowed_failures) * 100

    return {
        "slo_target": f"{slo_target * 100}%",
        "allowed_failures": int(total_allowed_failures),
        "actual_failures": failed_requests,
        "remaining_failures": int(remaining_failures),
        "budget_remaining": f"{budget_remaining_pct:.1f}%",
        "budget_exhausted": budget_remaining_pct <= 0,
    }

# Example: 99.9% SLO, 30-day window
result = calculate_error_budget(
    slo_target=0.999,
    window_days=30,
    total_requests=4_320_000,
    failed_requests=2_800
)
print(result)
# {'slo_target': '99.9%', 'allowed_failures': 4320,
#  'actual_failures': 2800, 'remaining_failures': 1520,
#  'budget_remaining': '35.2%', 'budget_exhausted': False}

error_budget_policy:
  service: payment-api
  slo_target: "99.9%"
  window: 30d

  thresholds:
    healthy:
      budget_remaining: ">50%"
      actions:
        - Normal deployment cadence
        - Feature work proceeds as planned
        - Risky experiments allowed with rollback plan

    warning:
      budget_remaining: "20-50%"
      actions:
        - Reduce deployment frequency
        - Require extra review on risky changes
        - Start investigating top error sources
        - No experimental features

    critical:
      budget_remaining: "<20%"
      actions:
        - Feature freeze -- reliability work only
        - All hands on fixing error sources
        - Post-incident reviews for budget-burning events
        - Escalate to engineering leadership

    exhausted:
      budget_remaining: "0%"
      actions:
        - Full deployment freeze
        - Mandatory blameless postmortem
        - Reliability improvements before any new features
        - Weekly check-ins until budget recovers