Azure Forgotten Resource Detective

Overview

The Azure Forgotten Resource Detective is a comprehensive PowerShell script designed to identify and analyze Azure resources that may be forgotten, unused, or misconfigured, potentially leading to unnecessary costs. This tool is part of the"FinOps for Everyone" series and helps organizations optimize their Azure spending by detecting orphaned resources and suspicious patterns.

Features

Resource Detection Capabilities

Cost Analysis

• Estimates monthly costs for identified resources
• Calculates potential savings from cleanup activities
• Provides cost impact assessments (High/Medium/Low)

Reporting

• HTML Report: Rich, interactive report with visual styling and actionable insights
• CSV Export: Structured data export for further analysis
• Console Summary: Real-time progress and summary information

Prerequisites

System Requirements

• PowerShell: Version 5.1 or later
• Azure CLI: Latest version installed and configured
• Azure Authentication: User must be logged in with az login

Required Permissions

• Reader: Access to subscription and resource groups
• Cost Management Reader: For cost analysis (optional but recommended)

Azure CLI Setup

# Install Azure CLI (if not already installed)
# Download from: https://docs.microsoft.com/en-us/cli/azure/install-azure-cli

# Login to Azure
az login

# Verify access to subscription
az account show

Usage

Basic Syntax

.orgotten-resource-detective.ps1 -SubscriptionId"<subscription-id>"

Parameters

Example Usage

Basic Analysis

# Analyze subscription with default settings
.orgotten-resource-detective.ps1 -SubscriptionId"12345678-1234-1234-1234-123456789012"

Custom Configuration

# Custom thresholds and output paths
.orgotten-resource-detective.ps1 \
 -SubscriptionId"12345678-1234-1234-1234-123456789012" \
 -DaysThreshold 60 \
 -OutputPath"C:\Reports\azure-analysis.html" \
 -CsvOutputPath"C:\Reports\azure-analysis.csv"

Enterprise Analysis

# Analyze multiple subscriptions
$subscriptions = @(
"12345678-1234-1234-1234-123456789012",
"87654321-4321-4321-4321-210987654321"
)

foreach ($sub in $subscriptions) {
 .\forgotten-resource-detective.ps1 \
 -SubscriptionId $sub \
 -OutputPath"report-$sub.html" \
 -CsvOutputPath"report-$sub.csv"
}

Detection Patterns

Orphaned Resources

The script identifies truly orphaned resources that incur costs without providing value:

Suspicious Patterns

Smart Exclusions

The script intelligently excludes managed resources to reduce false positives:

• AKS Managed Resources: Resource groups starting with MC_
• Private Endpoint NICs: NICs with private endpoint associations
• Service-Managed NICs: NICs with specific naming patterns or management tags

Cost Estimation

# Cost per GB per month (USD)
Standard_LRS: $0.05/GB
Premium_LRS: $0.135/GB
StandardSSD_LRS: $0.075/GB
Premium_ZRS: $0.169/GB
StandardSSD_ZRS: $0.094/GB

# Monthly costs (USD)
Basic SKU: $2.92/month
Standard SKU: $3.65/month

# Monthly costs (USD)
Basic SKU: $18.25/month
Standard SKU: $18.25/month

Report Output

HTML Report Structure

CSV Export

Structured data export containing all findings for:

• Further analysis in Excel/Power BI
• Integration with other tools
• Historical tracking and trending

Safety and Best Practices

Verification Process

# Always verify resources before deletion
az disk show --name"suspicious-disk" --resource-group"rg-name"
az network nic show --name"suspicious-nic" --resource-group"rg-name"

Stakeholder Consultation

• Contact application owners
• Review with infrastructure teams
• Check deployment documentation
• Verify with business stakeholders

Backup Considerations

# Create snapshots before deleting disks
az snapshot create --name"backup-snapshot" --source"disk-name" --resource-group"rg-name"

Risk Mitigation

False Positive Scenarios

Recommended Workflow

1. Generate Report: Run script to identify candidates
2. Business Review: Validate findings with stakeholders
3. Staged Cleanup: Delete resources in phases
4. Monitor Impact: Watch for any issues post-cleanup
5. Document Changes: Maintain cleanup audit trail

Troubleshooting

Common Issues

Authentication Problems

# Error: Please run 'az login' to setup account
az login --use-device-code # For environments without browser access

Permission Errors

# Error: Insufficient privileges
# Solution: Ensure user has Reader role on subscription
az role assignment list --assignee"user@domain.com" --subscription"sub-id"

Large Subscription Timeouts

# For subscriptions with many resources, consider:
# 1. Running during off-peak hours
# 2. Analyzing specific resource groups
# 3. Increasing PowerShell execution timeout
$ProgressPreference = 'SilentlyContinue' # Speeds up execution

Debug Mode

# Enable verbose output for troubleshooting
$VerbosePreference = 'Continue'
.orgotten-resource-detective.ps1 -SubscriptionId"sub-id" -Verbose

Integration Options

Automation Scenarios

Scheduled Reports

# Windows Task Scheduler or Azure Automation
# Run weekly/monthly for continuous monitoring
schtasks /create /tn"Azure Resource Detective" /tr"powershell.exe -File C:\Scripts\detective.ps1 -SubscriptionId 'sub-id'" /sc weekly

CI/CD Integration

# Azure DevOps Pipeline example
- task: PowerShell@2
 displayName: 'Run Resource Detective'
 inputs:
 filePath: 'scripts/forgotten-resource-detective.ps1'
 arguments: '-SubscriptionId $(subscriptionId)'

Email Notifications

# Add email functionality
$reportPath ="forgotten-resources-report.html"
Send-MailMessage -To"admin@company.com" -Subject"Azure Resource Report" -Body"See attached" -Attachments $reportPath

Data Export Integration

Power BI Integration

# Use CSV output for Power BI dashboards
$csvData = Import-Csv"forgotten-resources-report.csv"
# Process and upload to Power BI dataset

ServiceNow Integration

# Create tickets for resource cleanup
foreach ($resource in $highRiskResources) {
 # API call to ServiceNow to create cleanup ticket
}

Performance Considerations

Script Optimization

• Parallel Processing: Consider using ForEach-Object -Parallel for large subscriptions
• Selective Analysis: Target specific resource groups if full subscription scan is too slow
• Caching: Store intermediate results for repeated analysis

Resource Limits

• API Throttling: Azure CLI may throttle requests for large subscriptions
• Memory Usage: Large datasets may require memory optimization
• Execution Time: Full subscription analysis can take 5-30 minutes depending on size

Version History and Maintenance

Maintenance Tasks

• Monthly: Update cost estimates based on Azure pricing changes
• Quarterly: Review and update suspicious patterns
• Annually: Validate detection logic against new Azure services

Conclusion

The Azure Forgotten Resource Detective is a powerful tool for Azure cost optimization and resource governance. Regular use can help organizations:

• Reduce Costs: Identify and eliminate unnecessary expenses
• Improve Governance: Maintain clean, well-organized Azure environments
• Enhance Visibility: Better understand resource usage patterns
• Support Compliance: Maintain proper resource tagging and documentation