Running Terraform Plan Locally

Introduction

Terraform, combined with Docker, offers a powerful solution for managing infrastructure as code. Running Terraform locally allows for faster development and testing cycles. In this guide, we’ll explore how to run Terraform locally using Docker, add variables to your Terraform configurations, and handle volume mappings on Windows.

Prerequisites

Before getting started, ensure you have the following:

• Docker installed on your local machine
• Terraform installed on your local machine
• A text editor (e.g., VS Code, Vim)

Setting Up Terraform Locally

1. Install Terraform and Docker

If you haven’t installed Terraform or Docker yet, you can download and install them from the following links:

• Terraform Installation Guide
• Docker Installation Guide

2. Initialize Terraform Configuration

Create a new directory for your Terraform project and navigate into it:

mkdir terraform-local-demo
cd terraform-local-demo

Initialize a new Terraform configuration:

terraform init

3. Create main.tf and Add Configuration

Create a main.tf file in your project directory and add the following configuration:

terraform {
  required_providers {
    docker = {
      source  = "kreuzwerker/docker"
      version = "~> 3.0.1"
    }
  }
}

provider "docker" {}

variable "docker_image_name" {
  description = "Name of the Docker image"
  default     = "nginx:latest"
}

# Docker image resource
resource "docker_image" "nginx" {
  name         = var.docker_image_name
  keep_locally = false
}

# Define a Docker container resource
resource "docker_container" "my_container" {
  image = docker_image.nginx.name
  name  = "my_nginx_container"
  
  # Define volume mapping
  volumes {
    # Path on the Windows host
    host_path      = "/c/Users/username/data"
    # Path in the container
    container_path = "/data"
    # Optional: Set read-only mode
    read_only      = false
  }
  
  # Set port mapping if needed
  ports {
    internal = 80
    external = 8080
  }
}

4. Apply Terraform Configuration

Apply the Terraform configuration to create the Docker container:

terraform apply

Advanced Configurations

Environment Variables

You can also add environment variables to your Docker container using the env block in the docker_container resource.

Network Configuration

To configure Docker networks for your containers, define a docker_network resource and set the network_mode in the docker_container resource.

Best Practices

• Immutable Infrastructure: Create new containers instead of updating existing ones for consistency.

• Use Variables: Utilize Terraform variables for flexible and reusable configurations.

• State Management: Store Terraform state files remotely using backend configurations.

Conclusion

Running Terraform locally with Docker provides a convenient way to manage infrastructure as code on your local machine. By adding variables and configuring volume mappings, you can create flexible and reusable Terraform configurations tailored to your needs. Follow the steps and best practices outlined in this guide to harness the power of Terraform for managing Docker containers locally. Happy coding!