60 lines
1.9 KiB
Plaintext
60 lines
1.9 KiB
Plaintext
---
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page_title: Provisioners Without a Resource
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description: >-
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A null_resource allows you to configure provisioners that are not directly
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associated with a single existing resource.
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---
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# Provisioners Without a Resource
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[null]: https://registry.terraform.io/providers/hashicorp/null/latest/docs/resources/resource
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If you need to run provisioners that aren't directly associated with a specific
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resource, you can associate them with a `null_resource`.
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Instances of [`null_resource`][null] are treated like normal resources, but they
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don't do anything. Like with any other resource, you can configure
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[provisioners](/language/resources/provisioners/syntax) and [connection
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details](/language/resources/provisioners/connection) on a `null_resource`. You can also
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use its `triggers` argument and any meta-arguments to control exactly where in
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the dependency graph its provisioners will run.
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## Example usage
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```hcl
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resource "aws_instance" "cluster" {
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count = 3
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# ...
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}
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resource "null_resource" "cluster" {
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# Changes to any instance of the cluster requires re-provisioning
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triggers = {
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cluster_instance_ids = "${join(",", aws_instance.cluster.*.id)}"
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}
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# Bootstrap script can run on any instance of the cluster
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# So we just choose the first in this case
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connection {
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host = "${element(aws_instance.cluster.*.public_ip, 0)}"
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}
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provisioner "remote-exec" {
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# Bootstrap script called with private_ip of each node in the cluster
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inline = [
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"bootstrap-cluster.sh ${join(" ", aws_instance.cluster.*.private_ip)}",
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]
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}
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}
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```
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## Argument Reference
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In addition to meta-arguments supported by all resources, `null_resource`
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supports the following specific arguments:
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- `triggers` - A map of values which should cause this set of provisioners to
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re-run. Values are meant to be interpolated references to variables or
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attributes of other resources.
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