---
page_title: vault function reference
description: The `vault` function retrieves secrets from HashiCorp Vault KV stores. Learn how to use the `vault` function in Packer templates.
---

# `vault` Function

Retrieves secrets from a HashiCorp Vault KV store. Packer can read secrets from and add them to your template as user variables. The `vault` function is available only within the default value of a user variable, allowing you to default a user variable to a vault secret.

Refer to the [Vault documentation](/vault/docs/commands/kv) for additional information about the Vault KV store.

An example of using a v2 kv engine:

If you store a value in vault using `vault kv put secret/hello foo=world`, you
can access it using the following:

```hcl
locals {
    foo = vault("/secret/data/hello", "foo")
}
```

which will assign `local.foo` with the value "world"

An example of using a v1 kv engine:

If you store a value in vault using:

    vault secrets enable -version=1 -path=secrets kv
    vault kv put secrets/hello foo=world

You can access it using the following:

```hcl
locals {
    foo = vault("secrets/hello", "foo")
}
```

This example accesses the Vault path `secret/foo` and returns the value
stored at the key `foo`, storing it as the local variable `local.foo`.

If the Vault secret contains a highly sensitive value the `local` block, not to be confused with
the `locals` block, can be used to mark the value as sensitive.

```hcl
local "foo" {
    expression = vault("secrets/hello", "foo")
    sensitive  = true
}
```

The `local` block example accesses the Vault path `secrets/foo` and returns the value
stored at the key `foo`, storing it as the local variable `local.foo`. However, the output of
the newly stored local variable will be filtered from the Packer build output, and replaced
with the value `<sensitive>`. See [Local Values](/packer/docs/templates/hcl_templates/locals) for more details.


## Usage

In order for the Vault function to work, you must set the environment variables `VAULT_TOKEN`
and `VAULT_ADDR` to valid values.

-> **NOTE:** HCL functions can be used in local variable definitions or inline
with a provisioner/post-processor. They cannot be used in global variable definitions.

The api tool we use allows for more custom configuration of the Vault client via
environment variables.

The full list of available environment variables is:

```text
"VAULT_ADDR"
"VAULT_AGENT_ADDR"
"VAULT_CACERT"
"VAULT_CAPATH"
"VAULT_CLIENT_CERT"
"VAULT_CLIENT_KEY"
"VAULT_CLIENT_TIMEOUT"
"VAULT_SKIP_VERIFY"
"VAULT_NAMESPACE"
"VAULT_TLS_SERVER_NAME"
"VAULT_WRAP_TTL"
"VAULT_MAX_RETRIES"
"VAULT_TOKEN"
"VAULT_MFA"
"VAULT_RATE_LIMIT"
```

and detailed documentation for usage of each of those variables can be found
[here](/vault/docs/commands#environment-variables).
