Terraform Tutorial — terraform plan

1 minute read

terraform plan shows you exactly what Terraform will do — create, update, or destroy — before making any changes.

Running plan

$ terraform plan

Terraform will perform the following actions:

  # aws_s3_bucket.main will be created
  + resource "aws_s3_bucket" "main" {
      + arn            = (known after apply)
      + bucket         = "my-app-bucket"
      + id             = (known after apply)
      + region         = "us-east-1"
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Reading the Plan Output

Symbol Meaning Color
+ Create Green
~ Update in place Yellow
-/+ Destroy and recreate Red/Green
- Destroy Red

Example with updates:

  # aws_instance.web will be updated in-place
  ~ resource "aws_instance" "web" {
      ~ instance_type = "t3.micro" -> "t3.small"
        # (other attributes unchanged)
    }

Plan with Variable Files

$ terraform plan -var-file="environments/prod.tfvars"

Saving a Plan

Save the plan to a file and apply it later:

# Save the plan
$ terraform plan -out=tfplan

# Apply the saved plan (no confirmation needed)
$ terraform apply tfplan

This is critical for CI/CD pipelines:

  1. plan stage: terraform plan -out=tfplan
  2. Manual approval step
  3. apply stage: terraform apply tfplan

Plan Exit Codes

Exit Code Meaning Use in CI/CD
0 No changes needed Skip apply
1 Error occurred Fail the pipeline
2 Changes detected Proceed to apply

Use -detailed-exitcode to get exit code 2:

$ terraform plan -detailed-exitcode
$ echo $?  # 0, 1, or 2

Targeting Specific Resources

Plan for a single resource:

$ terraform plan -target=aws_s3_bucket.main

⚠️ Warning: Targeting skips resources that depend on the targeted one. Use only for debugging, not regular workflow.

What’s Next?

You’ve reviewed the plan. Let’s execute it with terraform apply.

← terraform init terraform apply →

You may also enjoy