terraform/website/docs/provisioners/index.html.markdown

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---
layout: "docs"
page_title: "Provisioners"
sidebar_current: "docs-provisioners"
description: |-
Provisioners are used to execute scripts on a local or remote machine as part of resource creation or destruction.
---
# Provisioners
Provisioners are used to execute scripts on a local or remote machine
as part of resource creation or destruction. Provisioners can be used to
bootstrap a resource, cleanup before destroy, run configuration management, etc.
Provisioners are added directly to any resource:
```hcl
resource "aws_instance" "web" {
# ...
provisioner "local-exec" {
command = "echo ${self.private_ip} > file.txt"
}
}
```
For provisioners other than local execution, you must specify
[connection settings](/docs/provisioners/connection.html) so Terraform knows
how to communicate with the resource.
## Creation-Time Provisioners
Provisioners by default run when the resource they are defined within is
created. Creation-time provisioners are only run during _creation_, not
during updating or any other lifecycle. They are meant as a means to perform
bootstrapping of a system.
If a creation-time provisioner fails, the resource is marked as **tainted**.
A tainted resource will be planned for destruction and recreation upon the
next `terraform apply`. Terraform does this because a failed provisioner
can leave a resource in a semi-configured state. Because Terraform cannot
reason about what the provisioner does, the only way to ensure proper creation
of a resource is to recreate it. This is tainting.
You can change this behavior by setting the `on_failure` attribute,
which is covered in detail below.
## Destroy-Time Provisioners
If `when = "destroy"` is specified, the provisioner will run when the
resource it is defined within is _destroyed_.
Destroy provisioners are run before the resource is destroyed. If they
fail, Terraform will error and rerun the provisioners again on the next
`terraform apply`. Due to this behavior, care should be taken for destroy
provisioners to be safe to run multiple times.
Destroy-time provisioners can only run if they remain in the configuration
at the time a resource is destroyed. If a resource block with a destroy-time
provisioner is removed entirely from the configuration, its provisioner
configurations are removed along with it and thus the destroy provisioner
won't run. To work around this, a multi-step process can be used to safely
remove a resource with a destroy-time provisioner:
* Update the resource configuration to include `count = 0`.
* Apply the configuration to destroy any existing instances of the resource, including running the destroy provisioner.
* Remove the resource block entirely from configuration, along with its `provisioner` blocks.
* Apply again, at which point no further action should be taken since the resources were already destroyed.
This limitation may be addressed in future versions of Terraform. For now,
destroy-time provisioners must be used sparingly and with care.
## Multiple Provisioners
Multiple provisioners can be specified within a resource. Multiple provisioners
are executed in the order they're defined in the configuration file.
You may also mix and match creation and destruction provisioners. Only
the provisioners that are valid for a given operation will be run. Those
valid provisioners will be run in the order they're defined in the configuration
file.
Example of multiple provisioners:
```hcl
resource "aws_instance" "web" {
# ...
provisioner "local-exec" {
command = "echo first"
}
provisioner "local-exec" {
command = "echo second"
}
}
```
## Failure Behavior
By default, provisioners that fail will also cause the Terraform apply
itself to error. The `on_failure` setting can be used to change this. The
allowed values are:
- `"continue"` - Ignore the error and continue with creation or destruction.
- `"fail"` - Error (the default behavior). If this is a creation provisioner,
taint the resource.
Example:
```hcl
resource "aws_instance" "web" {
# ...
provisioner "local-exec" {
command = "echo ${self.private_ip} > file.txt"
on_failure = "continue"
}
}
```