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This page is useful, but it's easier to tell what it's for if we put it next to the page about connections.
62 lines
1.9 KiB
Markdown
62 lines
1.9 KiB
Markdown
---
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layout: "docs"
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page_title: "Provisioners Without a Resource"
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sidebar_current: "docs-provisioners-null-resource"
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description: |-
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The `null_resource` is a resource allows you to configure provisioners that
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are not directly associated with a single existing resource.
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---
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# Provisioners Without a Resource
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[null]: /docs/providers/null/resource.html
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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](/docs/provisioners/index.html) and [connection
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details](/docs/provisioners/connection.html) 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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