What is Terraform Plan and Apply?

Question

Accepted Answer

**Plan** — preview changes before applying. **Apply** — execute infrastructure changes.

```bash
# Initialize
terraform init
terraform init -upgrade
terraform init -migrate-state

# Plan
terraform plan
terraform plan -out=tfplan
terraform plan -target=aws_instance.web
terraform plan -destroy
terraform plan -var="environment=staging"

# Apply
terraform apply
terraform apply tfplan
terraform apply -auto-approve
terraform apply -target=aws_instance.web
terraform apply -parallelism=10

# Destroy
terraform destroy
terraform destroy -target=aws_instance.web

# Format and validate
terraform fmt -recursive
terraform validate
terraform console

# Workspace management
terraform workspace list
terraform workspace new staging
terraform workspace select production
```

**Plan output:**
- resource_to_add: resources to create.
- resource_to_change: resources to update.
- resource_to_destroy: resources to delete.

**Best Practices:**
- Always plan before apply.
- Save plan output for audit.
- Use -target for surgical changes.

DevOps: What is Terraform Plan and Apply?