The Terraform import workflow allows you to bring existing infrastructure resources under Terraform management. This is essential when you have manually created resources or resources from other tools that you want to manage consistently through Infrastructure as Code.
**Import Workflow Steps:**
…The Terraform import workflow allows you to bring existing infrastructure resources under Terraform management. This is essential when you have manually created resources or resources from other tools that you want to manage consistently through Infrastructure as Code.
**Import Workflow Steps:**
1. **Write Configuration First**: Before importing, create a Terraform configuration block that matches the existing resource. Define the resource type and a logical name in your .tf files.
2. **Run Import Command**: Execute `terraform import <resource_address> <resource_id>` to associate the existing resource with your configuration. The resource_id format varies by provider and resource type.
3. **Verify State**: After importing, Terraform adds the resource to your state file. Run `terraform plan` to identify any configuration drift between your written config and the actual resource.
4. **Refine Configuration**: Adjust your configuration until `terraform plan` shows no changes, ensuring your code accurately represents the imported resource.
**Best Practices:**
- **Backup State Files**: Always backup your terraform.tfstate before importing to prevent data loss.
- **Import One Resource at a Time**: This approach helps isolate issues and makes troubleshooting easier.
- **Use Import Blocks (Terraform 1.5+)**: The newer `import` block syntax allows declarative imports within configuration files, enabling plan-based imports and better collaboration.
- **Document Resource IDs**: Keep records of resource identifiers used during import for audit purposes.
- **Review Provider Documentation**: Each resource type has specific import syntax requirements documented in provider docs.
- **Test in Non-Production First**: Practice import workflows in development environments before applying to production infrastructure.
- **Use Version Control**: Commit configuration changes after successful imports to track infrastructure history.
- **Consider Using terraform state show**: After import, this command helps verify what attributes Terraform captured, ensuring complete configuration alignment.
Import Workflow and Best Practices in Terraform
Why Import Workflow Matters
In real-world infrastructure management, you often encounter resources that were created manually through cloud provider consoles or by other tools before Terraform was adopted. The import workflow allows you to bring these existing resources under Terraform management, enabling you to benefit from infrastructure as code practices for your entire environment.
What is Terraform Import?
Terraform import is a command that allows you to take existing infrastructure resources and bring them into your Terraform state file. This creates a mapping between the real-world resource and your Terraform configuration, allowing Terraform to manage that resource going forward.
The basic syntax is: terraform import [options] ADDRESS ID
Where ADDRESS is the resource address in your configuration (e.g., aws_instance.example) and ID is the provider-specific resource identifier.
How the Import Workflow Works
Step 1: Write the Configuration First Before importing, you must write a resource block in your Terraform configuration that matches the resource you want to import. Terraform import does NOT generate configuration automatically (though terraform plan -generate-config-out can help with this in newer versions).
Step 2: Run the Import Command Execute the terraform import command with the resource address and the cloud provider's resource ID.
Step 3: Verify with Plan Run terraform plan to check if your configuration matches the imported resource. Any differences will show as planned changes.
Step 4: Refine Configuration Adjust your configuration until terraform plan shows no changes, ensuring your code accurately represents the existing resource.
Best Practices for Importing Resources
1. Always Backup State First Before any import operation, backup your current state file. Import modifies state, and mistakes can be difficult to reverse.
2. Import to a Separate State Initially Consider importing into a temporary workspace or separate state file first to verify the import works correctly.
3. Use Data Sources When Possible If you only need to reference existing resources rather than manage them, consider using data sources instead of importing.
4. Document the Import Process Keep records of what was imported, when, and any configuration adjustments needed.
5. Verify No Unintended Changes Always run terraform plan after importing to ensure no unexpected modifications will occur.
6. Handle Dependencies Carefully When importing multiple related resources, import them in the correct dependency order.
Import Block (Terraform 1.5+)
Newer versions of Terraform support an import block in configuration: import { to = aws_instance.example id = "i-1234567890abcdef0"}
This declarative approach allows imports to be planned and reviewed before applying.
Limitations of Import
- Import only updates state, not configuration - Not all resources support import - Some resource attributes may not be importable - Complex resources may require manual configuration refinement
Exam Tips: Answering Questions on Import Workflow and Best Practices
Key Points to Remember:
1. Configuration is Required First - The exam frequently tests whether you know that you must write the resource configuration before importing. Terraform import does NOT auto-generate configuration files.
2. State Modification Only - Understand that terraform import modifies the state file to include the resource mapping. It does not create or modify .tf configuration files.
3. Syntax Recognition - Be familiar with the command syntax: terraform import RESOURCE_ADDRESS RESOURCE_ID. Know what constitutes valid addresses and IDs.
4. Post-Import Verification - Questions may ask what to do after importing. The correct answer involves running terraform plan to verify configuration matches the imported resource.
5. Use Cases - Recognize scenarios where import is appropriate: bringing legacy resources under Terraform management, adopting IaC for existing infrastructure, or recovering from state file issues.
6. Import Block Knowledge - For recent exam versions, understand the import block syntax and how it differs from the CLI command approach.
7. Distinguish from Data Sources - Know when to use import versus data sources. Import is for managing resources; data sources are for reading existing resource information.
Common Exam Question Patterns: - What happens to configuration files when you run terraform import? (Answer: Nothing - they are not modified) - What must exist before running terraform import? (Answer: A corresponding resource block in configuration) - What should you do after importing a resource? (Answer: Run terraform plan to verify configuration accuracy)