Reference library

Observability & SRE

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

6 matches

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…

18 0 Open

Observability & SRE easy

Generate Synthetic CPU Utilization Metrics in Python

Creates realistic time-series CPU utilization samples with timestamps, noise, and output as structured JSON for observability demos and testing.

observability metrics time-series

Python

from datetime import datetime, timedelta
import random
import json


def generate_metric_samples(base_value, noise, count=60, interval_minutes=1):
    """Generate realistic CPU utilization samples for a given time window."""
    timestamps = []
    values = []

    now = datetime.utcnow()
    start_time = now - timede…

14 0 Open

Observability & SRE easy

How to Build a Metrics Counter with Increment and Snapshot in Python

A simple dict-backed MetricsCounter class that increments named counters and returns a snapshot of the current values.

metrics counter observability

Python

class MetricsCounter:
    def __init__(self):
        self._metrics = {}

    def increment(self, key, delta=1):
        self._metrics[key] = self._metrics.get(key, 0) + delta

    def snapshot(self):
        return dict(self._metrics)


if __name__ == "__main__":
    counter = MetricsCounter()
    counter.increment("…

13 0 Open

Observability & SRE easy

How to Parse Log Lines with Regex in Python

Extracts timestamp, log level, service name, and message from a log line using compiled regex named groups.

regex logging parsing

Python

import re

LOG_PATTERN = re.compile(
    r'^(?P<timestamp>\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}) '
    r'\[(?P<level>\w+)\] '
    r'\((?P<service>[^)]+)\) '
    r'(?P<message>.*)$'
)

def parse_log_line(line: str) -> dict:
    match = LOG_PATTERN.match(line)
    if not match:
        return {"error": "invalid log format…

14 0 Open

Observability & SRE easy

Mocking a Metrics Gauge's set_value Method in Python

Demonstrates using unittest.mock.Mock with wraps to intercept a gauge's set_value call while verifying arguments and preserving real behavior.

unittest mocking metrics

Python

from unittest.mock import Mock

class MetricsGauge:
    def __init__(self, name):
        self.name = name
        self.value = 0.0

    def set_value(self, new_value):
        self.value = float(new_value)
        return self.value

# Usage demonstration with a mock
gauge = MetricsGauge("cpu_usage")
gauge_mock = Mock…

13 0 Open

Observability & SRE easy

Rotate Log Files by Size in Python

A mock log rotation script that renames log files exceeding a size threshold, appending numbered backups.

log-rotation pathlib file-management

Python

import os
from pathlib import Path

def rotate_logs(directory: str, max_size: int = 100) -> None:
    """Rotate log files that exceed max_size bytes."""
    log_dir = Path(directory)
    for log_file in sorted(log_dir.glob("*.log"), key=lambda p: str(p)):
        if log_file.stat().st_size > max_size:
            for …

13 0 Open

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