Day 5 — Terraform Variables

1. Variables Based on Purpose (Most Important)

1️⃣ Input Variables

Used to pass values into Terraform.

• Avoid hardcoding

• Make configs reusable

• Can be mandatory or optional (via default)

Common sources:

• terraform.tfvars

• *.auto.tfvars

• -var / -var-file

• TF_VAR_<name>

• default value

2️⃣ Local Variables

Used for derived values and reuse inside a module.

• Reduce duplication

• Improve readability

• Cannot be overridden

Best for naming conventions and expressions.

3️⃣ Output Variables

Expose values after terraform apply.

• Share values across modules

• Show important info (IP, IDs)

• Can be marked sensitive

2. Variables Based on Values (High Level)

• Primitive: string, number, bool

• Complex: list, set, map, object, tuple

• Special: null (absence of value)

Variable Precedence (High → Low)

1. -var / -var-file

2. *.auto.tfvars

3. terraform.tfvars

4. TF_VAR_<name>

5. default value

Last applied value wins.

Must Remember

• Always define type

• Use locals to avoid repetition

• Never hardcode secrets

• Mark sensitive outputs

• Keep variables organized (variables.tf, outputs.tf)

For more detail check Github Code:- https://github.com/sidharthhhh/terraform/tree/main/day5
Check this vedio for more clearity:- https://youtu.be/V-2yC39BONc?si=KAjKH7EFhK0BsV3P