ephemeralasnull function reference

This topic provides reference information about the ephemeralasnull function. The ephemeralasnull function accepts an ephemeral value and returns null.

Introduction

You can use the ephemeralasnull function to nullify ephemeral values. For example, if you pass an object with a nested ephemeral value to ephemeralasnull,it nullifies any ephemeral values within that object.

Syntax

Use the ephemeralasnull function with the following syntax:

ephemeralasnull(var.my_ephemeral_value)

In the following example, you can pass the ephemeralasnull function an ephemeral value, and the function returns null:

variable "example" {
  type      = string
  default   = "test"
  ephemeral = true
}

# This output returns null.
output "example_output" {
  value       = ephemeralasnull(var.example)
}

For more information on which Terraform blocks can be ephemeral, refer to ephemeral inputs, outputs, and resources.

Example use case

The following example shows how you can use the ephemeralasnull function to intake a map that contains some ephemeral values, and output the values that are not ephemeral.

variable "session_token" {
  type      = string
  default   = "test"
  ephemeral = true
}

variable "configuration" {
  type = map(string)
  default = {
    "env" = "development"
  }
}

# This is a contrived example, but this pattern works with any object that is a mix of ephemeral and non-ephemeral values. 
locals {
  configuration_with_token = merge(
    var.configuration,
    { "session_token" = var.session_token }
  )
  ephemeral = true
}

output "configuration_settings" {
# Using ephemeralasnull enables you to output the non-ephemeral values.
  value       = ephemeralasnull(local.things_with_token)
  description = "Environment setting."
}

When you apply the above configuration, Terraform returns the ephemeral values in locals.configuration_settings as null. This lets you output the non-ephemeral value env.

Outputs:

configuration_settings = {
  "env" = "development"
  "session_token" = tostring(null)
}