Prevent_destroy lifecycle rule in Terraform - Step-by-Step Execution

Process Flow - Prevent_destroy lifecycle rule

Define resource with prevent_destroy

↓

Terraform plan detects destroy

↓

Check lifecycle.prevent_destroy

↓

Block destroy

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Error message

Terraform checks if a resource marked with prevent_destroy is about to be destroyed. If yes, it blocks the action and shows an error.

Execution Sample

Terraform

resource "aws_s3_bucket" "example" {
  bucket = "my-bucket"
  lifecycle {
    prevent_destroy = true
  }
}

Defines an S3 bucket resource that Terraform will not allow to be destroyed.

Process Table

Step	Action	Resource State	Lifecycle Rule Check	Result
1	Terraform plan detects resource destroy	Resource exists	Check prevent_destroy	Proceed to check rule
2	Check lifecycle.prevent_destroy	Resource exists	prevent_destroy = true	Destroy blocked
3	Terraform blocks destroy	Resource exists	prevent_destroy enforced	Error: Destroy prevented
4	User cancels destroy	Resource remains	No destroy	No change
5	If prevent_destroy was false	Resource exists	prevent_destroy = false	Destroy allowed

💡 Destroy blocked because prevent_destroy is true on the resource

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
resource_exists	true	true	true	true	true
prevent_destroy	true	true	true	true	true
destroy_allowed	false	false	false	false	false

Key Moments - 2 Insights

Why does Terraform show an error instead of destroying the resource?

Because the lifecycle.prevent_destroy rule is set to true, Terraform blocks any destroy action as shown in execution_table step 3.

What happens if prevent_destroy is set to false or omitted?

Terraform allows the resource to be destroyed normally, as shown in execution_table step 5.

Visual Quiz - 3 Questions

Look at the execution table, at which step does Terraform block the destroy action?

A Step 4

B Step 2

C Step 3

D Step 5

💡 Hint

Check the 'Result' column for the step where 'Destroy blocked' and 'Error' appear.

According to the variable tracker, what is the value of 'destroy_allowed' after step 3?

A false

B true

C undefined

D null

💡 Hint

Look at the 'destroy_allowed' row under 'After Step 3' in variable_tracker.

If prevent_destroy was false, what would Terraform do according to the execution table?

A Block destroy and show error

B Allow destroy

C Ignore the resource

D Retry destroy multiple times

💡 Hint

See step 5 in execution_table under 'Result' column.

Concept Snapshot

Terraform lifecycle prevent_destroy rule:
- Add lifecycle { prevent_destroy = true } inside resource block
- Blocks any destroy action on that resource
- Terraform plan errors if destroy attempted
- Useful to protect critical resources from accidental deletion

Full Transcript

This visual execution trace shows how Terraform handles the prevent_destroy lifecycle rule. When a resource is marked with prevent_destroy true, Terraform detects any destroy action during plan and blocks it, showing an error. The resource remains intact. If prevent_destroy is false or omitted, Terraform allows the destroy normally. Variables track resource existence and destroy permission. Key moments clarify why errors occur and what changes if the rule is off. The quiz tests understanding of when and how Terraform blocks destruction.