Run Terraform Linting Locally

This document highlights the steps needed in order to perform linting of the terraform files locally.

All information was taken from this page but I have only included the necessary information.

Install TFLint

MacOS - Homebrew:

brew install tflint

Windows - Chocolatey:

choco install tflint

Open a terminal and cd into the terraform directory. Run the following command

tflint --init

TFLint runs on the root module by default. It does not support recursion (similar to how terraform operates).

Run the following command to run tflint on the main module and other modules we use within the project

tflint --module

tflint --module security

tflint --module networking

tflint --module database

tflint --module storage

tflint --module compute

At the moment there are no errors returned by the TFLint tool which is what we want.

To simualte a TFLint warning to see how tool works.

Open up the file terraform/database/database.tf

Search for the text instance_class = var.dbase_instance_type

Replace it with the text instance_class = "db.t3.micro123"

This test will simualte a tflint warning as the instance type db.t3.micro123 does not exist

Run the command tflint --module database

The returned error should be similar to the following message

Error: "db.t3.micro123" is invalid instance type. (aws_db_instance_invalid_type)

on database/database.tf line 80: 80: instance_class = "db.t3.micro123"

Reference: https://github.com/terraform-linters/tflint-ruleset-aws/blob/v0.5.0/docs/rules/aws_db_instance_invalid_type.md