Terraform CLI

Terraform CLI

Infrastructure as code tool. Define cloud resources in HCL, plan changes, and apply them safely.

• Official repo: https://github.com/hashicorp/terraform
• Docs: https://developer.hashicorp.com/terraform/cli

Core Workflow

terraform init        # Initialize working directory, download providers
terraform plan        # Preview changes
terraform apply       # Apply changes (with confirmation)
terraform apply -auto-approve  # Apply without confirmation
terraform destroy     # Destroy all managed resources

Common Commands

State Management

terraform state list                      # List all resources in state
terraform state show aws_instance.my_vm   # Show resource details
terraform state mv old_name new_name      # Rename resource
terraform state rm resource_name          # Remove from state (not destroyed)
terraform state pull                      # Download remote state

Planning

terraform plan -out=plan.tfplan           # Save plan to file
terraform apply plan.tfplan               # Apply saved plan
terraform plan -target=aws_instance.my_vm # Plan specific resource
terraform plan -var="region=us-west-2"    # Pass variable
terraform plan -var-file=prod.tfvars      # Use variable file

Workspace Management

terraform workspace list
terraform workspace new staging
terraform workspace select production
terraform workspace show

Output and Formatting

terraform output                          # Show all outputs
terraform output -json                    # JSON format
terraform output db_endpoint              # Specific output
terraform fmt                             # Format HCL files
terraform validate                        # Validate configuration

Import

terraform import aws_instance.my_vm i-1234567890abcdef0

Agent Best Practices

• Always run terraform plan before terraform apply to preview changes
• Use -out=plan.tfplan to save plans and apply them exactly
• Use -target flag sparingly - only for debugging specific resources
• Use terraform output -json for machine-readable output
• Run terraform fmt before committing to keep consistent formatting
• Use terraform validate to check syntax without accessing providers
• Never store state files in git - use remote backends (S3, GCS, Terraform Cloud)
• Use -auto-approve only in automated pipelines, not for manual runs

Example Workflows

Initialize and deploy

terraform init
terraform plan -out=deploy.tfplan
terraform apply deploy.tfplan

Check current infrastructure

terraform state list
terraform output -json | jq