open-nomad/website/content/docs/job-specification/hcl2/functions/uuid/uuidv5.mdx

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---
layout: docs
page_title: uuidv5 - Functions - Configuration Language
description: |-
The uuidv5 function generates a uuid v5 string representation of the value in
the specified namespace.
---
# `uuidv5` Function
`uuidv5` generates a _name-based_ UUID, as described in [RFC 4122 section
4.3](https://tools.ietf.org/html/rfc4122#section-4.3), also known as a "version
5" UUID.
```hcl
uuidv5(namespace, name)
```
Unlike the pseudo-random UUIDs generated by [`uuidv4`](/docs/job-specification/hcl2/functions/uuid/uuidv4),
name-based UUIDs derive from namespace and an name, producing the same UUID
value every time if the namespace and name are unchanged.
Name-based UUID namespaces are themselves UUIDs, but for readability this
function accepts some keywords as aliases for the namespaces that were assigned
by RFC 4122:
| Keyword | Namespace ID | Name format |
| -------- | -------------------------------------- | ---------------------------------------------------------------------------- |
| `"dns"` | `6ba7b810-9dad-11d1-80b4-00c04fd430c8` | A fully-qualified DNS domain name. |
| `"url"` | `6ba7b811-9dad-11d1-80b4-00c04fd430c8` | Any valid URL as defined in [RFC 3986](https://tools.ietf.org/html/rfc3986). |
| `"oid"` | `6ba7b812-9dad-11d1-80b4-00c04fd430c8` | An [ISO/IEC object identifier](https://oidref.com/) |
| `"x500"` | `6ba7b814-9dad-11d1-80b4-00c04fd430c8` | [X.500 Distinguished Name](https://tools.ietf.org/html/rfc1779) |
To use any other namespace not included in the above table, pass its assigned
namespace ID directly in the first argument in the usual UUID string format.
## Examples
Use the namespace keywords where possible, to make the intent more obvious to
a future reader:
```shell-session
> uuidv5("dns", "nomadproject.io")
d2616d48-e1cb-5b87-8a8c-46355decc76a
> uuidv5("url", "https://nomadproject.io/")
a1572394-3948-5251-b0c7-b4ded43587b4
> uuidv5("oid", "1.3.6.1.4")
af9d40a5-7a36-5c07-b23a-851cd99fbfa5
> uuidv5("x500", "CN=Example,C=GB")
84e09961-4aa4-57f8-95b7-03edb1073253
```
The namespace keywords treated as equivalent to their corresponding namespace
UUIDs, and in some special cases it may be more appropriate to use the
UUID form:
```shell-session
> uuidv5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "nomadproject.io")
d2616d48-e1cb-5b87-8a8c-46355decc76a
```
If you wish to use a namespace defined outside of RFC 4122, using the namespace
UUID is required because no corresponding keyword is available:
```shell-session
> uuidv5("743ac3c0-3bf7-4a5b-9e6c-59360447c757", "LIBS:diskfont.library")
ede1a974-df7e-5f17-84b9-76208818b2c8
```
When using raw UUID namespaces, consider including a comment alongside the
expression that indicates which namespace this represents in a
human-significant manner, such as by reference to the standard that defined it.
## Related Functions
- [`uuidv4`](/docs/job-specification/hcl2/functions/uuid/uuidv4), which generates pseudorandom UUIDs.