WEBVTT

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In this lecture, we will take a look
at the Terraform taint and untaint command.

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There would be cases
when a resource creation fails

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when we run Terraform apply.

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Let's take the same example as before

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where we use a local provisioner
to store the public IP address

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of the EC2 instance in a file.

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However, when we try to apply the changes,

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the resource creation failed

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because the part specified in the command
of the local exit provisioner is invalid.

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When this happens and a resource creation
fails for any reason,

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Terraform marks the resource as tainted.

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This can be seen when we run
the Terraform plan command again.

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The resource called web server is tainted,

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and as a result, Terraform will attempt
to recreate it during the subsequent apply.

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In this example,

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the step that failed was the command
executed by the local exit provisioner.

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The EC2 instance itself was
successfully provisioned.

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In spite of this, Terraform will attempt
to recreate the entire resource

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because it was marked tainted.

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Now there would be cases when we want to
force a particular resource to be recreated.

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For example, consider a case where manual
changes were made to an AWS instance

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which is managed by Terraform,

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such as changing the version of nginx
running on it by manual methods.

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To reword this, we can either
destroy the resource

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using the command Terraform destroy,
and then run apply again,

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or the better way would be
to taint the resource

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using the Terraform taint command like this.

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When we run Terraform plan next,

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we will see that the resource
is set to be recreated.

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To undo a taint that was applied
for a specific resource,

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use the Terraform untaint command like this.

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This resource will not be recreated now
during a subsequent Terraform apply.