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PRD Web Scraping

Module: Error Logging & Alerting

Technical Specification specifically for the Scraper Modules

Overview

This module provides real-time observability into the scraping pipeline by identifying, logging, and notifying relevant stakeholders of failures or anomalies. It helps ensure data reliability, facilitates rapid debugging, and reduces downtime by proactively reporting issues like scraper crashes, missing fields, or zero scraped records.

Technical Component

Component

Technology / Tool

Purpose

Log Manager

Python logging module

Centralized logger for scraper events and errors

Retry Handler

Scrapy RetryMiddleware / Custom Logic

Automatically retries failed requests

Alert Dispatcher

SMTP / Slack API

Sends email or Slack alerts based on thresholds

Status Aggregator

Python Scheduled Job

Compiles daily health summary of all scraping jobs

Log Storage

AWS CloudWatch / Azure Logs / S3

Stores structured logs and summaries for audit and debugging

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Input/Output Specification

Type

Format

Description

Input

Scraper events (success, failure, errors)

Logged internally at runtime

Output

Log files (.log or .json), Alert messages

Real-time alerts and daily health reports

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Functional Capabilities

Logging Job Status

The system must log every job execution with metadata:

Job name, start/end time, execution duration

Success/failure outcome

Number of records scraped

Error count, if any

Retry Logic

The system must automatically retry network errors (timeouts, DNS failures) up to 3 attempts.

Retry delay must use exponential backoff to avoid overwhelming target sites.

Data Extraction Failures

The system must log missing or null values for critical fields (e.g., price, make).

Non-critical field failures (e.g., optional specs) must be logged as warnings.

For each failed field extraction:

Log the field name, URL of listing, and error context.

Real-Time Alerts

The system must trigger alerts when:

A scraper fails to complete

Zero listings are retrieved from a run

30% of records have critical missing fields

Alerts must include:

Source site name

Timestamp

Issue summary

Link to detailed logs

Alerts are sent via:

Email (SMTP)

Slack (Webhook integration)

Daily Summary Reports

At the end of each day, the system must generate a summary report per site:

Total runs

Success/failure ratio

Total listings scraped

Most frequent error types

Average runtime

Reports are:

Stored in S3 or Log Aggregator

Sent optionally via email to project team

Sample Log Format

json

CopyEdit

{

"timestamp": "2025-04-07T03:10:00Z",

"scraper": "JustLease",

"status": "success",

"duration_sec": 184,

"records_scraped": 132,

"critical_errors": 0,

"missing_fields": {

"price_per_month": 3,

"mileage_per_year": 6

"log_level": "info"

}

Security & Reliability

Logs must exclude PII and any sensitive system credentials.

All alert messages are rate-limited to prevent spamming.

If the alerting service fails (e.g., Slack down), the system must queue or log alert attempts for retry.

Extensibility Options

Alert Threshold Config: Allow project admin to define alert conditions (e.g., >20% missing fields).

Multiple Channels: Add support for SMS or Opsgenie integration.

Log Visualization: Integrate with tools like Grafana or Kibana to visualize log trends.