Observability &amp; SRE

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 metrics time-series

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.

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…

logging json observability

How to Do Structured JSON Line Logging in Python

Create a simple JSON-lines logger that writes one JSON object per line to stdout with timestamp, level, message, and custom context fields.

import json
import sys
from datetime import datetime

class JsonLineLogger:
    def __init__(self, stream=sys.stdout):
        self.stream = stream

    def log(self, level, message, **context):
        record = {
            "timestamp": datetime.utcnow().isoformat() + "Z",
            "level": level,
            "me…

15 0 Open

logging json observability

How to Do Structured JSON Logging in Python

Create a custom logging formatter that outputs each log entry as a single JSON line with timestamp, level, logger name, and message.

import json
import logging
from datetime import datetime


class JsonFormatter(logging.Formatter):
    def format(self, record):
        log_entry = {
            "timestamp": datetime.utcnow().isoformat() + "Z",
            "level": record.levelname,
            "logger": record.name,
            "message": record.ge…

observability dataclasses tracing

How to Model Span Events in Python

Define a Span class with timestamped milestone events and a completion marker to track operation lifecycle.

import time
from dataclasses import dataclass, field
from enum import Enum
from typing import List


class SpanStatus(Enum):
    STARTED = "started"
    COMPLETED = "completed"


@dataclass
class SpanEvent:
    name: str
    timestamp: float = field(default_factory=time.time)
    attributes: dict = field(default_facto…

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

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…