82 lines
3.0 KiB
Plaintext
82 lines
3.0 KiB
Plaintext
---
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layout: docs
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page_title: uuidv5 - Functions - Configuration Language
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sidebar_title: 'uuidv5'
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sidebar_current: configuration-functions-uuid-uuidv5
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description: |-
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The uuidv5 function generates a uuid v5 string representation of the value in
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the specified namespace.
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---
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# `uuidv5` Function
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`uuidv5` generates a _name-based_ UUID, as described in [RFC 4122 section
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4.3](https://tools.ietf.org/html/rfc4122#section-4.3), also known as a "version
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5" UUID.
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```
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uuidv5(namespace, name)
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```
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Unlike the pseudo-random UUIDs generated by [`uuidv4`](./uuidv4.html),
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name-based UUIDs derive from namespace and an name, producing the same UUID
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value every time if the namespace and name are unchanged.
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Name-based UUID namespaces are themselves UUIDs, but for readability this
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function accepts some keywords as aliases for the namespaces that were assigned
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by RFC 4122:
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| Keyword | Namespace ID | Name format |
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| -------- | -------------------------------------- | ---------------------------------------------------------------------------- |
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| `"dns"` | `6ba7b810-9dad-11d1-80b4-00c04fd430c8` | A fully-qualified DNS domain name. |
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| `"url"` | `6ba7b811-9dad-11d1-80b4-00c04fd430c8` | Any valid URL as defined in [RFC 3986](https://tools.ietf.org/html/rfc3986). |
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| `"oid"` | `6ba7b812-9dad-11d1-80b4-00c04fd430c8` | An [ISO/IEC object identifier](https://oidref.com/) |
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| `"x500"` | `6ba7b814-9dad-11d1-80b4-00c04fd430c8` | [X.500 Distinguished Name](https://tools.ietf.org/html/rfc1779) |
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To use any other namespace not included in the above table, pass its assigned
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namespace ID directly in the first argument in the usual UUID string format.
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## Examples
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Use the namespace keywords where possible, to make the intent more obvious to
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a future reader:
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```shell
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> uuidv5("dns", "www.packer.io")
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a5008fae-b28c-5ba5-96cd-82b4c53552d6
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> uuidv5("url", "https://www.packer.io/")
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9db6f67c-dd95-5ea0-aa5b-e70e5c5f7cf5
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> uuidv5("oid", "1.3.6.1.4")
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af9d40a5-7a36-5c07-b23a-851cd99fbfa5
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> uuidv5("x500", "CN=Example,C=GB")
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84e09961-4aa4-57f8-95b7-03edb1073253
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```
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The namespace keywords treated as equivalent to their corresponding namespace
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UUIDs, and in some special cases it may be more appropriate to use the
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UUID form:
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```shell
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> uuidv5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.packer.io")
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a5008fae-b28c-5ba5-96cd-82b4c53552d6
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```
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If you wish to use a namespace defined outside of RFC 4122, using the namespace
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UUID is required because no corresponding keyword is available:
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```shell
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> uuidv5("743ac3c0-3bf7-4a5b-9e6c-59360447c757", "LIBS:diskfont.library")
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ede1a974-df7e-5f17-84b9-76208818b2c8
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```
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When using raw UUID namespaces, consider including a comment alongside the
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expression that indicates which namespace this represents in a
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human-significant manner, such as by reference to the standard that defined it.
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## Related Functions
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- [`uuidv4`](./uuid.html), which generates pseudorandom UUIDs.
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