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Unveiling Terraform Apply Command: Transforming Configurations into Reality

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Saurabh Adhau
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3 min read

Unveiling Terraform Apply Command: Transforming Configurations into Reality

Table of contents

Introduction

In the realm of Terraform, the terraform apply command is the gateway to actualizing your infrastructure configurations. This guide delves into the intricacies of terraform apply, dissecting the processes that unfold when you unleash this command. An illustrative example will guide us through the transformative journey from configuration to reality.

1. Terraform Apply: Turning Configurations into Reality

When you're ready to bring your infrastructure vision to life, the terraform apply command is the instrumental step that executes the changes defined in your Terraform configuration. It orchestrates the creation, modification, or deletion of resources according to your specifications.

2. Example Scenario: AWS EC2 Instance Creation

Let's walk through an example where we utilize terraform apply to create an AWS EC2 instance. The configuration specifies an instance with specific attributes.

2.1. Configuration Breakdown:

# main.tf

provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "example_instance" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
}

2.2. Explanation:

2.2.1. provider "aws" Block:

We define the AWS provider configuration with the desired region for our infrastructure.

provider "aws" {
  region = "us-east-1"
}

2.2.2. resource "aws_instance" Block:

A basic AWS EC2 instance resource is defined to illustrate the Terraform configuration.

resource "aws_instance" "example_instance" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
}

3. Application Process: What Happens?

When you run terraform apply, a series of pivotal processes unfold:

3.1. Plan Generation:

  • Terraform generates an execution plan based on your configuration, highlighting the changes to be applied.

3.2. Resource Creation/Modification/Deletion:

  • Based on the plan, Terraform applies the changes, creating, modifying, or deleting resources as necessary.

3.3. Approval Prompt:

  • You're prompted to review the execution plan before proceeding. Confirm with a "yes" to initiate the changes.

3.4. Execution:

  • Terraform executes the plan, interacting with the cloud provider's API to bring your infrastructure to the desired state.

3.5. State Update:

  • The local state file is updated to reflect the changes. If using a remote backend, the remote state is also updated.

3.6. Success Confirmation:

  • Terraform provides a detailed summary of the changes applied and confirms the successful execution of the configuration.

4. Verification: Checking the Result

After applying the changes, you can verify the status of your resources in the cloud provider's console or by querying Terraform outputs.

5. Applying the Configuration:

To apply the configuration changes, use the following command:

terraform apply

6. Conclusion: From Blueprint to Reality

terraform apply is the culmination of your Terraform orchestration journey. It transforms configurations into tangible infrastructure, shaping your cloud environment according to your specifications.

As you venture further into Terraform, mastery of the apply command empowers you to iterate, refine, and evolve your infrastructure with confidence. May your infrastructure transformations be seamless and your applications of Terraform bring your visions to life! 🚀🏗️

Terraform applyTerraform