Ownership and Project Delivery Questions

from datetime import datetime, timedelta, timezone

def compute_burn_rate(events, slo_window_minutes, error_sli):
    """
    events: list of {'ts': '2025-01-10T12:34:56Z', 'is_error': bool}
    slo_window_minutes: int or float window length in minutes (lookback from now)
    error_sli: allowed error fraction (e.g., 0.01 for 99% success SLO)
    Returns: burn_rate (float). 0 means no burn; float('inf') if budget is zero and there are errors.
    """
    if slo_window_minutes <= 0:
        raise ValueError("slo_window_minutes must be > 0")
    if not (0.0 <= error_sli < 1.0):
        raise ValueError("error_sli must be in [0.0, 1.0)")

    now = datetime.now(timezone.utc)
    window_start = now - timedelta(minutes=slo_window_minutes)

    total = 0
    errors = 0

    for ev in events:
        ts = ev.get('ts')
        if ts is None:
            continue
        # parse ISO timestamps ending with 'Z' (UTC)
        try:
            # e.g., '2025-01-10T12:34:56Z'
            dt = datetime.fromisoformat(ts.replace('Z', '+00:00'))
        except Exception:
            # skip malformed timestamps
            continue

        if not (window_start <= dt <= now):
            continue

        total += 1
        if ev.get('is_error'):
            errors += 1

    if total == 0:
        # No data in window -> treat as no observed errors (conservative: 0 burn).
        return 0.0

    observed_error_rate = errors / total

    remaining_budget_fraction = 1.0 - error_sli
    if remaining_budget_fraction == 0.0:
        # SLO allows zero errors (100% success). If any errors observed, burn is infinite.
        return float('inf') if errors > 0 else 0.0

    burn_rate = observed_error_rate / remaining_budget_fraction
    return burn_rate