This commit adds 3 new HCL2 functions:
* `sum`: computes the sum of a collection of numerical values
* `startswith`: checks if a string has another as prefix
* `endswith`: checks if a string has another as suffix
# Description
The output of the example on [uuidv4 Function](https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/uuid/uuidv4) is not a valid RFC compliant UUIDv4. It indicates the usage of the `uuidv4()` function and outputs `b5ee72a3-54dd-c4b8-551c-4bdc0204cedb` which is not a valid UUIDv4.
I've corrected the example to output a UUIDv4 conforming to the RFC as such `xxxxxxxx-xxxx-4xxx-Nxxx-xxxxxxxxxxxx`, where:
- The 13th character is always `4` (indicating version 4).
- The 17th character must be either `8`, `9`, `a`, or `b` (indicating the first character of the variant).
# Changes
```diff
- b5ee72a3-54dd-c4b8-551c-4bdc0204cedb
+ 9fc99a70-7cd5-482d-bb2b-03af016e4e94
```
Replaces the old UUID output with a valid RFC compliant UUIDv4.
# References
- [RFC 4122](https://datatracker.ietf.org/doc/html/rfc4122)
- [RFC 9562](https://datatracker.ietf.org/doc/html/rfc9562)
# Misc.
To make sure this wasn't an issue with the `uuidv4()` function within Hashicorp's [packer](https://github.com/hashicorp/packer) I tested the function in the following way:
### Command executed:
```ps
> .\packer.exe inspect .\uuid.pkr.hcl
```
### Contents of the _uuid.pkr.hcl_ file:
```hcl
locals {
uuid_0 = uuidv4()
uuid_1 = uuidv4()
uuid_2 = uuidv4()
uuid_3 = uuidv4()
uuid_4 = uuidv4()
uuid_5 = uuidv4()
uuid_6 = uuidv4()
uuid_7 = uuidv4()
uuid_8 = uuidv4()
uuid_9 = uuidv4()
}
```
### Output:
```ps
Packer Inspect: HCL2 mode
> input-variables:
> local-variables:
local.uuid_0: "90877db8-5519-46ea-ae15-7dfb92594064"
local.uuid_1: "fe6a4649-97d9-4686-b981-3295175f941a"
local.uuid_2: "9944d83d-dab2-4cfb-a1db-572d19271e7a"
local.uuid_3: "547cddb7-c979-4b87-90d0-2bd9b68858b5"
local.uuid_4: "c13dc47a-552c-4dfb-a75d-2f63bb248b41"
local.uuid_5: "3db1ce29-bdde-4642-b010-1a41d47c22a3"
local.uuid_6: "4a020460-edd1-471d-b8a2-5956c0c68257"
local.uuid_7: "1845bf87-6908-4fc0-8f11-b5b4f36c60a7"
local.uuid_8: "f5c7e552-b799-45f3-8172-46162eadfd89"
local.uuid_9: "057c2eaf-6769-4a8d-90c8-775aec80496a"
> builds:
```
Adds an example of a string template being used.
The example demonstrates how a template sequence can be used to embed the value of a variable into a string that can be used as script content.
Ref: #12651
Signed-off-by: Ryan Johnson <ryan.johnson@broadcom.com>
Compared to Terraform, Packer was lacking a capability to encode/decode
strings to/from base64-encoded text encoded with another encoding.
This could be problematic in some cases, mainly when working with
Windows, as most of the OS uses UTF-16LE as its standard encoding for
many operations.
Therefore, we take a page from Terraform here, and add those functions
to what Packer supports in an HCL2 context.
The HCL2 docs on built-in functions contains a link to a non-existent
section of the expressions page, so we update it to link to the general
page, and to the string interpolation section, since it is a common use
case.
* clarify local and input variables
* Apply suggestions from code review
Co-authored-by: Rose M Koron <32436232+rkoron007@users.noreply.github.com>
* Apply suggestions from code review
Co-authored-by: Rose M Koron <32436232+rkoron007@users.noreply.github.com>
Co-authored-by: Wilken Rivera <wilken@hashicorp.com>
* Apply suggestions from code review
Co-authored-by: Wilken Rivera <wilken@hashicorp.com>
---------
Co-authored-by: Rose M Koron <32436232+rkoron007@users.noreply.github.com>
Co-authored-by: Wilken Rivera <wilken@hashicorp.com>
