How to Use TFLint for Terraform Linting

Use tflint to analyze your Terraform files for errors and style issues by running tflint in your Terraform project directory. It scans your code and reports problems to help you write better, error-free Terraform configurations.

Syntax

The basic command to run TFLint is tflint. You run it inside your Terraform project folder where your .tf files are located. You can also use options like --init to set up plugins or --config to specify a custom config file.

• tflint: Runs linting on Terraform files in the current directory.
• tflint --init: Downloads and installs necessary plugins.
• tflint --config path/to/.tflint.hcl: Uses a custom configuration file.

bash

tflint [options]

# Common options:
# --init       Initialize plugins
# --config     Specify config file
# --help       Show help information

Example

This example shows how to run tflint on a simple Terraform project. It checks your Terraform files and prints any issues found.

bash

# Navigate to your Terraform project folder
cd my-terraform-project

# Initialize TFLint plugins (only needed once)
tflint --init

# Run TFLint to check your Terraform files
tflint

Output

Warning: aws_instance.example: attribute deprecated
Error: aws_s3_bucket.example: missing required argument 'acl'

Common Pitfalls

Common mistakes when using TFLint include:

• Running tflint outside the Terraform project folder, so no files are found.
• Not running tflint --init first, causing plugin errors.
• Ignoring warnings and errors reported by TFLint, which can lead to broken Terraform deployments.
• Using outdated TFLint versions missing latest rules.

Always run tflint --init before linting and fix reported issues promptly.

bash

## Wrong: Running tflint outside project folder
cd ~
tflint

## Right: Run inside project and initialize plugins
cd my-terraform-project
tflint --init
tflint

Quick Reference

Command	Description
tflint	Run linting on Terraform files in current directory
tflint --init	Download and install required plugins
tflint --config	Use a custom configuration file
tflint --help	Show help and usage information

Key Takeaways

Run tflint inside your Terraform project folder to check your code.

Use tflint --init once to install necessary plugins before linting.

Fix all warnings and errors reported by tflint to improve code quality.

Use a custom config file with --config to customize linting rules.

Keep tflint updated to get the latest linting checks and features.