Reference library

Observability & SRE

Structured logging, metrics, tracing, health checks, and SLO-friendly instrumentation.

4 matches

Calculate Error Rate from Log Stream in Python

Parses a mock log stream to count errors and compute the error percentage using a rolling window of recent entries.

import re
from collections import deque

def error_rate_from_log_stream(message):
    log_pattern = r'^\[(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})\] (ERROR|INFO|DEBUG): (.*)$'
    recent_entries = deque(maxlen=100)
    error_count = 0
    total_count = 0

    for line in message.strip().split('\n'):
        match = re.mat…

15 0 Open

Observability & SRE easy

Check if a Timestamp Falls in a Daily Maintenance Window in Python

A small Python function that returns True when a datetime falls inside a daily maintenance window, and a demo printing yes/no for sample timestamps.

maintenance datetime scheduling

Python

from datetime import datetime, timedelta
from zoneinfo import ZoneInfo


def in_maintenance_window(now: datetime, start_hour: int = 2, duration_hours: int = 4) -> bool:
    """Return True if 'now' falls inside the daily maintenance window."""
    day_start = now.replace(hour=start_hour, minute=0, second=0, microsecond…

15 0 Open

Observability & SRE easy

How to Compute SRE Metrics Like Error Rate and Availability in Python

Tracks log events in a sliding time window and calculates error rate per second and availability percentage using an easy-to-follow class.

observability sre metrics

Python

from collections import deque
from datetime import datetime, timedelta
from typing import Dict, Deque


class LogMetrics:
    """Simple observability helper to track log events and calculate SRE metrics."""

    def __init__(self, window_seconds: int = 60):
        self.window_seconds = window_seconds
        self.eve…

14 0 Open

Observability & SRE easy

How to mock Prometheus alert rule thresholds in Python

Simulate a Prometheus alert rule with a configurable threshold and duration window, firing only when the metric exceeds the threshold long enough.

prometheus alerting sre

Python

import time
import random


class MetricsStore:
    def __init__(self):
        self.metrics = {}

    def set_metric(self, name, value, labels=None):
        key = (name, tuple(sorted((labels or {}).items())))
        self.metrics[key] = value

    def get_metric(self, name, labels=None):
        key = (name, tuple(s…

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