Interview › Infrastructure as Code (Terraform, Ansible)
What is a tainted resource, and what replaced the taint command?
Infrastructure as Code (Terraform, Ansible) · Basic level
Answer
A tainted resource is a resource marked for replacement on the next plan. The older terraform taint command is deprecated. The recommended replacement is terraform apply -replace='resource.address' because replacement appears in the plan and can be reviewed before execution.
Technical explanation
-replace is explicit for one plan/apply operation instead of leaving a hidden taint in shared state.
It works well for degraded instances, corrupted volumes, or resources that need recreation after manual repair.
Review the replacement plan for dependencies and downtime.
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: What is a tainted resource, and what replaced the taint command?
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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