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In this lesson, you’ll learn how to use resource targeting with OpenTofu’s plan and apply commands to update individual resources without affecting the rest of your infrastructure.

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Example Configuration

Below is a sample HCL configuration that generates a random string and launches an AWS EC2 instance tagged with that string: 
resource "random_string" "server-suffix" {
  length  = 6
  upper   = false
  special = false
}

resource "aws_instance" "web" {
  ami           = "ami-06178cf087598769c"
  instance_type = "m5.large"
  tags = {
    Name = "web-${random_string.server-suffix.id}"
  }
}
The aws_instance.web resource uses the interpolation ${random_string.server-suffix.id} to append the generated suffix to the Name tag.

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Applying Changes Normally

If you change the random string’s length from 6 to 5 and run: 
$ tofu apply
OpenTofu will plan and apply updates for both resources because the EC2 tag depends on the random string: 
Plan: 1 to add, 1 to change, 1 to destroy.

Enter a value: yes
random_string.server-suffix: Destroying... [id=6r923x]
random_string.server-suffix: Creation complete after 0s [id=nglmpo]
aws_instance.web: Modifying... [id=i-67428769e06ae2901]
Apply complete! Resources: 1 added, 1 changed, 1 destroyed.

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Targeting a Single Resource

To update only the random string and leave the EC2 instance untouched, use the -target flag: 
$ tofu apply -target=random_string.server-suffix
OpenTofu will generate a plan for just that resource: 
OpenTofu will perform the following actions:

  # random_string.server-suffix must be replaced
-/+ resource "random_string" "server-suffix" {
    ~ id      = "bl12qd" -> (known after apply)
    ~ length  = 6 -> 5 # forces replacement
}

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

Warning: Resource targeting is in effect

Enter a value: yes
random_string.server-suffix: Destroying... [id=6r923x]
random_string.server-suffix: Creation complete after 0s [id=nglmpo]

Warning: Applied changes may be incomplete
Apply complete! Resources: 1 added, 0 changed, 1 destroyed.
Using resource targeting can leave your state incomplete. Reserve this feature for urgent fixes or small, isolated changes.

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CLI Commands Reference

CommandDescription
tofu planPreview all changes before applying them
tofu applyApply all planned changes
tofu apply -target=<RESOURCE_TYPE>.<NAME>Apply changes only to the specified resource

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