CloudFormation Deep Management Skill

Deep management of CloudFormation stacks, change sets, drift detection, stack sets, and rollbacks.

MANDATORY: Discovery-First Pattern

Always inspect stack status and recent events before operations.

Phase 1: Discovery

#!/bin/bash
echo "=== Active Stacks ==="
aws cloudformation list-stacks --stack-status-filter CREATE_COMPLETE UPDATE_COMPLETE UPDATE_ROLLBACK_COMPLETE ROLLBACK_COMPLETE --query 'StackSummaries[*].{Name:StackName,Status:StackStatus,Updated:LastUpdatedTime}' --output table 2>/dev/null | head -20

echo ""
echo "=== Failed Stacks ==="
aws cloudformation list-stacks --stack-status-filter CREATE_FAILED UPDATE_FAILED DELETE_FAILED --query 'StackSummaries[*].{Name:StackName,Status:StackStatus,Reason:StackStatusReason}' --output table 2>/dev/null | head -10

echo ""
echo "=== Stack Sets ==="
aws cloudformation list-stack-sets --status ACTIVE --query 'Summaries[*].{Name:StackSetName,Status:Status,DriftStatus:DriftStatus}' --output table 2>/dev/null | head -10

echo ""
echo "=== Exports ==="
aws cloudformation list-exports --query 'Exports[*].{Name:Name,Value:Value,Stack:ExportingStackId}' --output table 2>/dev/null | head -10

Phase 2: Analysis

#!/bin/bash
STACK="${1:?Stack name required}"

echo "=== Stack Detail ==="
aws cloudformation describe-stacks --stack-name "$STACK" --query 'Stacks[0].{Status:StackStatus,Created:CreationTime,Updated:LastUpdatedTime,DriftStatus:DriftInformation.StackDriftStatus}' --output table 2>/dev/null

echo ""
echo "=== Resources ==="
aws cloudformation list-stack-resources --stack-name "$STACK" --query 'StackResourceSummaries[*].{Logical:LogicalResourceId,Type:ResourceType,Status:ResourceStatus}' --output table 2>/dev/null | head -20

echo ""
echo "=== Recent Events ==="
aws cloudformation describe-stack-events --stack-name "$STACK" --query 'StackEvents[:10].[Timestamp,LogicalResourceId,ResourceStatus,ResourceStatusReason]' --output table 2>/dev/null | head -15

echo ""
echo "=== Drift Detection ==="
DRIFT_ID=$(aws cloudformation detect-stack-drift --stack-name "$STACK" --query 'StackDriftDetectionId' --output text 2>/dev/null)
echo "Drift detection started: $DRIFT_ID"
aws cloudformation describe-stack-drift-detection-status --stack-drift-detection-id "$DRIFT_ID" 2>/dev/null | jq '{Status: .DetectionStatus, DriftStatus: .StackDriftStatus, DriftedResources: .DriftedStackResourceCount}' 2>/dev/null

echo ""
echo "=== Outputs ==="
aws cloudformation describe-stacks --stack-name "$STACK" --query 'Stacks[0].Outputs[*].{Key:OutputKey,Value:OutputValue}' --output table 2>/dev/null | head -10

Output Rules

• TOKEN EFFICIENCY: Target <=50 lines per output
• Show resource status summaries, not full template dumps
• Highlight failed events and drift status
• Summarize nested stack hierarchy concisely

Safety Rules

• NEVER delete stacks without explicit confirmation
• Always create change sets before updating stacks
• Review change set resources before execution
• Enable termination protection on critical stacks
• Check cross-stack dependencies (exports/imports) before deletion
• Use --retain-resources for resources that cannot be deleted

Output Format

Present results as a structured report:

Managing Cloudformation Deep Report
═══════════════════════════════════
Resources discovered: [count]

Resource       Status    Key Metric    Issues
──────────────────────────────────────────────
[name]         [ok/warn] [value]       [findings]

Summary: [total] resources | [ok] healthy | [warn] warnings | [crit] critical
Action Items: [list of prioritized findings]

Target ≤50 lines of output. Use tables for multi-resource comparisons.

Anti-Hallucination Rules

1. NEVER assume resource names — always discover via CLI/API in Phase 1 before referencing in Phase 2.
2. NEVER fabricate metric names or dimensions — verify against the service documentation or --help output.
3. NEVER mix CLI commands between service versions — confirm which version/API you are targeting.
4. ALWAYS use the discovery → verify → analyze chain — every resource referenced must have been discovered first.
5. ALWAYS handle empty results gracefully — an empty response is valid data, not an error to retry.

Counter-Rationalizations

Shortcut	Counter	Why
"I'll skip discovery and check known resources"	Always run Phase 1 discovery first	Resource names change, new resources appear — assumed names cause errors
"The user only asked for a quick check"	Follow the full discovery → analysis flow	Quick checks miss critical issues; structured analysis catches silent failures
"Default configuration is probably fine"	Audit configuration explicitly	Defaults often leave logging, security, and optimization features disabled
"Metrics aren't needed for this"	Always check relevant metrics when available	API/CLI responses show current state; metrics reveal trends and intermittent issues
"I don't have access to that"	Try the command and report the actual error	Assumed permission failures prevent useful investigation; actual errors are informative