Day 62 - Automating Docker Containers with Terraform!

What You’ll Learn

1. Understanding Terraform Blocks and Resources.

2. Using Terraform to pull an Nginx Docker image and deploy a Docker container.

3. Running the setup step-by-step with appropriate commands.

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Step-by-Step Tasks

Task 01: Set Up Terraform with the Docker Provider

Terraform needs to know which provider to use. This is specified using the required_providers block in your main.tf file.

1. Create a main.tf File
   Start by creating a Terraform configuration file:

    mkdir terraform-docker-setup
    cd terraform-docker-setup
    touch main.tf
   

2. Add the Terraform Block
   This block tells Terraform to use the Docker provider plugin:

    terraform {
      required_providers {
        docker = {
          source  = "kreuzwerker/docker"  # Specify provider source
          version = "~> 2.21.0"          # Compatible provider version
        }
      }
    }
   

   Note:

   • kreuzwerker/docker refers to the plugin location on Terraform’s registry.

   • The version ~> 2.21.0 ensures compatibility with the latest versions of the Docker provider plugin.

3. Add the Provider Block
   The provider block configures the Docker provider:

    provider "docker" {}
   

4. Run Terraform Init
   Initialize the Terraform working directory to download the required provider:

    terraform init
   

   Expected Output:

   • Terraform will download the Docker provider plugin.

You can use this script to run nginx: Summarized

terraform {
  required_providers {
    docker = {
      source  = "kreuzwerker/docker"  # Specify provider source
      version = "~> 2.21.0"          # Compatible provider version
    }
  }
}

provider "docker" {}

resource "docker_image" "nginx" {
  name         = "nginx:latest"  # Specify the image name
  keep_locally = false           # Do not keep the image locally if not in use
}

resource "docker_container" "nginx" {
  image = docker_image.nginx.image_id  # Use the correct attribute for the image ID
  name  = "tutorial"

  ports {
    internal = 80
    external = 80
  }
}

This script will make you run nginx in your localhost:80 web browser

Commands used for execution: terraform init
terraform plan
terraform apply

Task 02: Create Resource Blocks for Nginx

Now you will define two resource blocks:

1. One for pulling the Nginx Docker image.

2. Another for running the Nginx container.

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Step 1: Pull the Nginx Docker Image

Add the following resource block to your main.tf file:

resource "docker_image" "nginx" {
  name         = "nginx:latest"  # Specify the image name
  keep_locally = false           # Do not keep the image locally if not in use
}

Explanation:

• docker_image is the resource type for Docker images.

• nginx is the logical name you give to this resource.

• name specifies the image to pull from Docker Hub.

• keep_locally = false ensures that unused images are removed.

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Step 2: Create a Docker Container for Nginx

Now add this block to create an Nginx container:

resource "docker_container" "nginx" {
  image = docker_image.nginx.latest  # Use the pulled Nginx image
  name  = "tutorial"                 # Container name

  ports {
    internal = 80  # Port exposed inside the container
    external = 80  # Port mapped to your host machine
  }
}

Explanation:

• docker_container is the resource type for containers.

• nginx is the logical name of the resource.

• image references the latest Nginx image you just pulled.

• ports maps port 80 from the container to port 80 on your local machine.

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Task 03: Apply Terraform Configuration

1. Run Terraform Plan
   Verify the configuration and preview the changes:

    terraform plan
   

2. Apply the Configuration
   Deploy the Nginx container using Terraform:

    terraform apply
   

   Expected Behavior:

   • Terraform will pull the Nginx image.

   • Terraform will run a container named tutorial exposing port 80.

3. Verify the Container
   Check if the container is running:

    sudo docker ps
   

   Expected Output:
   You should see the container with the name tutorial running and mapped to port 80.

4. Test the Nginx Setup
   Open a browser and visit http://localhost:80. You should see the default Nginx welcome page. 🎉

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Optional: Docker Installation Commands

If Docker is not installed on your machine, run the following: this is for linux ubuntu, for windows you can follow different steps.

sudo apt-get update
sudo apt-get install docker.io
sudo systemctl start docker
sudo systemctl enable docker
sudo chown $USER /var/run/docker.sock  # Grant Docker permissions to your user

Verify the installation: You can verify in your VS-code terminal also.

docker --version
docker ps