70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
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---
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layout: "random"
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page_title: "Random: random_id"
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sidebar_current: "docs-random-resource-id"
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description: |-
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Generates a random identifier.
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---
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# random\_id
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The resource `random_id` generates random numbers that are intended to be
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used as unique identifiers for other resources.
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Unlike other resources in the "random" provider, this resource *does* use a
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cryptographic random number generator in order to minimize the chance of
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collisions, making the results of this resource when a 32-byte identifier
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is requested of equivalent uniqueness to a type-4 UUID.
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This resource can be used in conjunction with resources that have,
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the `create_before_destroy` lifecycle flag set, to avoid conflicts with
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unique names during the brief period where both the old and new resources
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exist concurrently.
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## Example Usage
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The following example shows how to generate a unique name for an AWS EC2
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instance that changes each time a new AMI id is selected.
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```
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resource "random_id" "server" {
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keepers = {
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# Generate a new id each time we switch to a new AMI id
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ami_id = "${var.ami_id}"
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}
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byte_length = 8
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}
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resource "aws_instance" "server" {
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tags = {
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Name = "web-server ${random_id.server.hex}"
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}
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# Read the AMI id "through" the random_id resource to ensure that
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# both will change together.
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ami = "${random_id.server.keepers.ami_id}"
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# ... (other aws_instance arguments) ...
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}
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```
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## Argument Reference
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The following arguments are supported:
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* `byte_length` - (Required) The number of random bytes to produce. The
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minimum value is 1, which produces eight bits of randomness.
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* `keepers` - (Optional) Arbitrary map of values that, when changed, will
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trigger a new id to be generated. See
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[the main provider documentation](../index.html) for more information.
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## Attributes Reference
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The following attributes are exported:
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* `b64` - The generated id presented in base64, using the URL-friendly character set: case-sensitive letters, digits and the characters `_` and `-`.
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* `hex` - The generated id presented in padded hexadecimal digits. This result will always be twice as long as the requested byte length.
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* `decimal` - The generated id presented in non-padded decimal digits.
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