Learn how to leverage the power of Bash environment variables in your Terraform projects for dynamic and flexible configurations.
This guide explains how to utilize environment variables within your Terraform projects. We'll cover setting environment variables, accessing them in your Terraform configurations, and using them within scripts executed by Terraform. Additionally, we'll address handling special characters and important considerations for security and variable scope.
Set environment variables in your shell:
export TF_VAR_my_variable="value"
Replace "value"
with the desired value for your variable.
Access environment variables in Terraform:
resource "example_resource" "example" {
name = var.my_variable
}
Terraform automatically recognizes environment variables prefixed with TF_VAR_
.
Use environment variables in scripts within Terraform:
resource "null_resource" "example" {
provisioner "local-exec" {
command = "echo $TF_VAR_my_variable"
environment = {
CUSTOM_VAR = "another value"
}
}
}
$VAR_NAME
.environment
block within local-exec
lets you set additional environment variables for the script.Handle special characters and spaces:
export TF_VAR_my_variable='value with spaces'
echo "$TF_VAR_my_variable"
Remember:
The code demonstrates using environment variables in Terraform to configure an AWS EC2 instance. It sets environment variables for instance type and region, defines Terraform variables with defaults, and uses these variables in provider and resource configurations. A script within a null resource demonstrates accessing environment variables and a custom variable set within the script's environment. The example emphasizes handling potential spaces in environment variable values and using secure practices for sensitive information.
This example demonstrates how to use environment variables to configure a simple AWS EC2 instance.
1. Set environment variables:
export TF_VAR_instance_type="t2.micro"
export TF_VAR_aws_region="us-west-2"
2. Define your Terraform code:
# Variables with default values (can be overridden by environment variables)
variable "instance_type" {
default = "t3.micro"
}
variable "aws_region" {
default = "us-east-1"
}
# Provider configuration
provider "aws" {
region = var.aws_region
}
# Resource definition
resource "aws_instance" "example" {
ami = "ami-0c55b31ad2299a701" # Replace with your desired AMI
instance_type = var.instance_type
tags = {
Name = "Terraform Example Instance"
}
}
# Output the public IP address of the instance
output "public_ip" {
value = aws_instance.example.public_ip
}
3. Use environment variables in a script:
resource "null_resource" "startup_script" {
provisioner "local-exec" {
command = <<-EOT
#!/bin/bash
echo "Instance type: $TF_VAR_instance_type" > /tmp/instance_info.txt
echo "Region: $TF_VAR_aws_region" >> /tmp/instance_info.txt
echo "Custom variable: ${CUSTOM_VAR}" >> /tmp/instance_info.txt
EOT
environment = {
CUSTOM_VAR = "This is a custom value"
}
}
# Ensure this resource runs after the instance is created
depends_on = [aws_instance.example]
}
Explanation:
instance_type
and aws_region
.local-exec
provisioner demonstrates accessing environment variables within a script."$TF_VAR_instance_type"
and "$TF_VAR_aws_region"
in the script to handle potential spaces in the values.environment
block within local-exec
sets an additional environment variable CUSTOM_VAR
for the script.Running the code:
main.tf
.terraform init
to initialize the working directory.terraform apply
to create the infrastructure.This example shows how to leverage environment variables to customize your Terraform deployments. Remember to handle sensitive information securely and avoid storing it directly in environment variables.
.tfvars
files or the command line to pass variables for better maintainability and version control, especially for non-sensitive values.terraform output
or terraform console
to inspect the values of variables during your Terraform workflow.This document outlines how to leverage environment variables within your Terraform projects.
Key Takeaways:
export TF_VAR_your_variable="your_value"
.TF_VAR_
. Access these values within your Terraform code using var.your_variable
.$VAR_NAME
syntax. The environment
block within the local-exec
provisioner allows defining additional environment variables specifically for that script.This comprehensive guide detailed how to effectively use environment variables within your Terraform projects. From setting and accessing them in configurations and scripts to handling special characters and security considerations, you now have the knowledge to leverage environment variables for dynamic and flexible deployments. Remember to prioritize security by avoiding storing sensitive information directly in environment variables and explore robust secrets management solutions for enhanced protection. By following the best practices outlined, you can streamline your Terraform workflows and enhance the security and maintainability of your infrastructure as code.