Interview › Infrastructure as Code (Terraform, Ansible)
How do you target a specific resource with terraform apply, and why is it discouraged?
Infrastructure as Code (Terraform, Ansible) · Basic level
Answer
You can target a resource using terraform plan or apply -target=resource.address. It is discouraged as normal practice because it bypasses Terraform's full dependency graph and can leave the configuration partially converged. I reserve it for recovery or troubleshooting and follow it with a normal full plan.
Technical explanation
-target can skip resources that would normally be updated through dependency traversal.
It is acceptable for recovery, bootstrapping a dependency, or narrowing a failing troubleshooting run.
Always run a normal plan afterward to confirm full convergence.
Keep Terraform's ownership boundary clear: one state should own a resource or field, and other tools should consume published outputs instead of modifying it.
Use fmt, validate, linting, policy checks, plan review, and state locking before production applies.
Design for small blast radius by splitting state around lifecycle, permissions, and recovery boundaries.
Hands-on example
1. Practice lifecycle and dependency controls for: How do you target a specific resource with terraform apply, and why is it discouraged?
2. Add lifecycle rules deliberately:
resource "aws_db_instance" "prod" {
identifier = "prod-db"
lifecycle {
prevent_destroy = true
ignore_changes = [allocated_storage]
}
}
3. Force a reviewed replacement with:
terraform plan -replace='aws_instance.web["blue"]' -out=replace.tfplan
terraform apply replace.tfplan
4. Use depends_on only when references do not express the ordering. Then run terraform graph or inspect the plan to explain the dependency path.
5. If you use -target for recovery, immediately follow with a full terraform plan.
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