1--- 2layout: "language" 3page_title: "uuidv5 - Functions - Configuration Language" 4sidebar_current: "docs-funcs-crypto-uuidv5" 5description: |- 6 The uuidv5 function generates a uuid v5 string representation of the value in the specified namespace. 7--- 8 9# `uuidv5` Function 10 11`uuidv5` generates a _name-based_ UUID, as described in 12[RFC 4122 section 4.3](https://tools.ietf.org/html/rfc4122#section-4.3), 13also known as a "version 5" UUID. 14 15``` 16uuidv5(namespace, name) 17``` 18 19Unlike the pseudo-random UUIDs generated by 20[`uuid`](./uuid.html), name-based UUIDs derive from namespace and an name, 21producing the same UUID value every time if the namespace and name are 22unchanged. 23 24Name-based UUID namespaces are themselves UUIDs, but for readability this 25function accepts some keywords as aliases for the namespaces that were 26assigned by RFC 4122: 27 28| Keyword | Namespace ID | Name format | 29| ------- | ------------ | ----------- | 30| `"dns"` | `6ba7b810-9dad-11d1-80b4-00c04fd430c8` | A fully-qualified DNS domain name. | 31| `"url"` | `6ba7b811-9dad-11d1-80b4-00c04fd430c8` | Any valid URL as defined in [RFC 3986](https://tools.ietf.org/html/rfc3986). | 32| `"oid"` | `6ba7b812-9dad-11d1-80b4-00c04fd430c8` | An [ISO/IEC object identifier](https://oidref.com/) | 33| `"x500"` | `6ba7b814-9dad-11d1-80b4-00c04fd430c8` | [X.500 Distinguished Name](https://tools.ietf.org/html/rfc1779) | 34 35To use any other namespace not included in the above table, pass its assigned 36namespace ID directly in the first argument in the usual UUID string format. 37 38## Examples 39 40Use the namespace keywords where possible, to make the intent more obvious to 41a future reader: 42 43``` 44> uuidv5("dns", "www.terraform.io") 45a5008fae-b28c-5ba5-96cd-82b4c53552d6 46 47> uuidv5("url", "https://www.terraform.io/") 489db6f67c-dd95-5ea0-aa5b-e70e5c5f7cf5 49 50> uuidv5("oid", "1.3.6.1.4") 51af9d40a5-7a36-5c07-b23a-851cd99fbfa5 52 53> uuidv5("x500", "CN=Example,C=GB") 5484e09961-4aa4-57f8-95b7-03edb1073253 55``` 56 57The namespace keywords treated as equivalent to their corresponding namespace 58UUIDs, and in some special cases it may be more appropriate to use the 59UUID form: 60 61``` 62> uuidv5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.terraform.io") 63a5008fae-b28c-5ba5-96cd-82b4c53552d6 64``` 65 66If you wish to use a namespace defined outside of RFC 4122, using the namespace 67UUID is required because no corresponding keyword is available: 68 69``` 70> uuidv5("743ac3c0-3bf7-4a5b-9e6c-59360447c757", "LIBS:diskfont.library") 71ede1a974-df7e-5f17-84b9-76208818b2c8 72``` 73 74When using raw UUID namespaces, consider including a comment alongside the 75expression that indicates which namespace this represents in a 76human-significant manner, such as by reference to the standard that 77defined it. 78 79## Related Functions 80 81* [`uuid`](./uuid.html), which generates pseudorandom UUIDs. 82