---
page_title: keys function reference
description: The `keys` function returns a list of keys in a given map. Learn how to use the `key` function in Packer templates.
---

⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️
> [!IMPORTANT]  
> **Documentation Update:** Product documentation previously located in `/website` has moved to the [`hashicorp/web-unified-docs`](https://github.com/hashicorp/web-unified-docs) repository, where all product documentation is now centralized. Please make contributions directly to `web-unified-docs`, since changes to `/website` in this repository will not appear on developer.hashicorp.com.
⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️

# `keys` Function

`keys` takes a map and returns a list containing the keys from that map.

The keys are returned in lexicographical order, ensuring that the result will
be identical as long as the keys in the map don't change.

## Examples

```shell-session
> keys({a=1, c=2, d=3})
[
  "a",
  "c",
  "d",
]
```

## Related Functions

- [`values`](/packer/docs/templates/hcl_templates/functions/collection/values) returns a list of the _values_ from a map.
