Home/Tools/Terraform Plan Explainer

Terraform Plan Explainer

Analyze Terraform plans for security risks, blast radius, and dependencies. Understand infrastructure changes before applying them. Supports text and JSON formats.

Loading tool...

Need Expert Help with Infrastructure as Code?

Our DevOps and cloud engineering team can help you with Terraform best practices, infrastructure security reviews, migration planning, CI/CD integration, and reducing risk in your infrastructure changes.

Get Free Infrastructure ReviewView DevOps Services

Understanding Terraform Plans

A Terraform plan shows you what changes will be made to your infrastructure before you apply them. Understanding the symbols and structure helps you review changes effectively.

Terraform Change Symbols

+
Create: A new resource will be created. Low risk, but review resource type and configuration.
~
Update: An existing resource will be modified in-place. Check which attributes are changing.
-
Delete: A resource will be destroyed. High risk - ensure this is intentional.
-/+
Replace: Resource will be destroyed then recreated. Check for data loss risk and downtime.
<=
Read: Data source will be read during apply. Usually low risk.

Force Replacement

Some attribute changes require resource replacement. Look for comments like:

# forces replacement

Common examples: changing instance types, VPC CIDR blocks, database engines, or encryption settings. Plan for downtime and data migration.

Dependencies

Terraform automatically determines the order of operations based on resource dependencies:

  • Implicit: Resource references in attributes
  • Explicit: Using depends_on meta-argument
  • Create-before-destroy: New resource created before old one deleted

Security Best Practices for Terraform

  1. 1.
    Review security group changes carefully: Opening ports to 0.0.0.0/0 (especially 22, 3389, 3306, 5432) creates serious security risks. Always restrict access to specific IP ranges or use VPN/bastion hosts.
  2. 2.
    Never commit secrets to version control: Use environment variables, secret managers (AWS Secrets Manager, HashiCorp Vault), or encrypted backends. Check plans for accidentally exposed credentials.
  3. 3.
    Enable encryption by default: Ensure databases, storage buckets, and volumes have encryption enabled. Review any changes that disable encryption.
  4. 4.
    Test in non-production first: Always test infrastructure changes in development or staging environments before applying to production.
  5. 5.
    Use remote state with locking: Store state in remote backends (S3, Azure Blob, Terraform Cloud) with state locking to prevent concurrent modifications.
  6. 6.
    Implement least privilege IAM: Grant only the minimum permissions needed. Review any IAM policy changes for privilege escalation.
  7. 7.
    Use terraform plan -out: Save plans to a file to ensure the exact changes you reviewed are applied, preventing time-of-check to time-of-use issues.
  8. 8.
    Monitor for drift: Regularly run terraform plan to detect configuration drift from manual changes or external automation.

Common High-Risk Scenarios

⚠️ Database Changes

Database deletions or replacements can cause data loss and service downtime.

  • ✓ Create snapshots/backups before changes
  • ✓ Test restore procedures
  • ✓ Plan maintenance windows
  • ✓ Coordinate with application teams

⚠️ Network Changes

VPC, subnet, or security group changes can disrupt connectivity.

  • ✓ Document existing connectivity requirements
  • ✓ Test network changes in isolation
  • ✓ Have rollback plan ready
  • ✓ Consider using create-before-destroy

⚠️ IAM & Security

Permission changes can lock you out or create security vulnerabilities.

  • ✓ Review for privilege escalation
  • ✓ Maintain emergency access accounts
  • ✓ Test permission changes with test accounts
  • ✓ Document the reason for permission changes

ℹ️ State Management

State file issues can cause resources to be recreated unnecessarily.

  • ✓ Use remote state with versioning
  • ✓ Enable state locking
  • ✓ Backup state before major changes
  • ✓ Review terraform refresh output

How to Use This Tool

  1. 1.
    Generate your Terraform plan:terraform plan

    Or for JSON format:

    terraform plan -out=tfplan && terraform show -json tfplan > plan.json
  2. 2.
    Paste your plan: Copy the output and paste it into the tool above. The tool will auto-detect whether it's text or JSON format.
  3. 3.
    Review the analysis: The tool will show you a summary dashboard, security concerns, resource changes grouped by risk level, and detailed analysis for each resource.
  4. 4.
    Take action: Address any critical or high-risk issues, review security concerns, and ensure you understand the blast radius before applying changes.
  5. 5.
    Export if needed: Export the analysis to JSON or Markdown format for documentation, team review, or CI/CD integration.

References & Citations

  1. HashiCorp. Terraform Plan Command Reference. Retrieved from https://developer.hashicorp.com/terraform/cli/commands/plan
  2. HashiCorp. JSON Output Format. Retrieved from https://developer.hashicorp.com/terraform/internals/json-format
  3. Spacelift. Terraform Security Best Practices. Retrieved from https://spacelift.io/blog/terraform-security
  4. DiggerHQ. Understanding and Limiting Terraform Blast Radius. Retrieved from https://medium.com/@DiggerHQ/understanding-and-limiting-terraform-blast-radius-da071673df16
  5. Firefly. Terraform Drift Detection Guide. Retrieved from https://www.firefly.ai/academy/terraform-drift-detection-guide

Note: These citations are provided for informational and educational purposes. Always verify information with the original sources and consult with qualified professionals for specific advice related to your situation.

Frequently Asked Questions

Common questions about the Terraform Plan Explainer

Terraform is an Infrastructure as Code (IaC) tool that manages cloud resources declaratively. A plan explainer helps you understand what changes Terraform will make before applying them, reducing the risk of production incidents, security issues, and unexpected infrastructure changes. It provides risk scoring, security analysis, and blast radius assessment.

Explore More Tools

Continue with these related tools

Developer
🌐

HTTP Request Builder

Interactive developer tool for constructing, sending, and analyzing HTTP requests directly from the browser

Try it now
Developer
🔄

CSV to JSON Converter

Convert CSV files to JSON format instantly with browser-based processing

Try it now
Developer
📊

Excel to JSON Converter

Convert Excel spreadsheets to JSON with multi-sheet support and custom formatting options

Try it now
Developer
🧾

YAML to JSON Converter

Convert YAML to JSON or JSON to YAML with full support for comments and anchors

Try it now
Developer
📝

Diff Checker

Compare text, code, or configuration files side by side

Try it now
Developer
🆔

GUID/UUID Generator

Generate unique identifiers for development and testing

Try it now

ℹ️ Disclaimer

This tool is provided for informational and educational purposes only. All processing happens entirely in your browser - no data is sent to or stored on our servers. While we strive for accuracy, we make no warranties about the completeness or reliability of results. Use at your own discretion.