Environment variables (TF_VAR_) in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of environment variables prefixed with TF_VAR_ in Terraform?

They allow you to set Terraform input variables outside of configuration files, making it easier to manage sensitive or environment-specific values.

beginner

How does Terraform use an environment variable named TF_VAR_region?

Terraform automatically maps TF_VAR_region to the input variable named region in your Terraform configuration.

intermediate

Why might you prefer using TF_VAR_ environment variables over hardcoding variables in Terraform files?

Using TF_VAR_ environment variables keeps sensitive data out of code, supports different environments easily, and avoids committing secrets to version control.

intermediate

Can you use TF_VAR_ environment variables to set complex types like lists or maps in Terraform?

Yes, but you must provide the value as a JSON string that Terraform can parse into the complex type.

intermediate

What happens if both a Terraform variable file and a TF_VAR_ environment variable set the same variable?

The TF_VAR_ environment variable takes precedence over the variable file value.

What prefix must an environment variable have to be recognized by Terraform as an input variable?

A TERRAFORM_VAR_

B TF_VAR_

C TF_INPUT_

D VAR_

Terraform recognizes environment variables starting with TF_VAR_ as input variables.

How should you format a list variable when setting it via a TF_VAR_ environment variable?

A Comma-separated string without quotes

B Plain string with brackets

C Space-separated string

D JSON string representing the list

Terraform expects complex types like lists to be passed as JSON strings in TF_VAR_ environment variables.

If you set a variable in both a .tfvars file and a TF_VAR_ environment variable, which one does Terraform use?

A TF_VAR_ environment variable value

B .tfvars file value

C The first one declared in the configuration

D Terraform throws an error

TF_VAR_ environment variables override values set in .tfvars files.

Why is using TF_VAR_ environment variables considered a best practice for sensitive data?

A Because they encrypt the data automatically

B Because they are easier to type

C Because they keep sensitive data out of code and version control

D Because Terraform ignores them in logs

Using environment variables avoids storing secrets in code or version control systems.

Which of the following is a valid TF_VAR_ environment variable for a Terraform variable named 'password'?

A TF_VAR_password=MySecret123

B TF_VAR_password='MySecret123'

C TF_VAR_password:MySecret123

D TF_VAR_password MySecret123

The correct syntax is TF_VAR_variableName=value without quotes or special characters.

Explain how Terraform uses environment variables prefixed with TF_VAR_ to set input variables.

Think about how environment variables can replace or override variable files.

Describe best practices and benefits of using TF_VAR_ environment variables in Terraform projects.

Consider security and flexibility advantages.