🌟 Introduction of Terraform 🌟

Terraform is an Infrastructure as Code (IaC), open-source, cloud-independent provisioning tool developed by HashiCorp using the Go programming language. It defines, provides, and manages infrastructure resources to comprehend the various components and how they interact in the provision of cloud resources. You can write code that specifies your entire infrastructure, even if your servers are handled by different organizations, such as AWS or Azure. Terraform helps you develop and manage these resources in parallel across providers as a single language and connective tissue to manage your whole IT infrastructure.

🛠️ How Does Terraform Work? 🛠️

Terraform uses version control and configuration files to assist you in defining and managing your entire infrastructure. It uses the Core and Providers, the two primary parts of the Terraform architecture.

💼 How Terraform Core Works 💼

Terraform core requires two input sources to function. First, the user configures the source input into Terraform, specifying which resources need to be created or made available. Second, data feeds into Terraform about the current infrastructure configuration. After receiving these inputs, IaC decides what needs to be done. It compares the current state with the user-specified desired state and configures the architecture to close the differences. In essence, Terraform Core determines what needs to be added, changed, or removed to completely provision your infrastructure.

Furthermore, it is the process of reading and analyzing configuration files based on the dependencies between resources to establish the sequence in which they must be created or altered with suppliers to develop or alter infrastructure resources. State management keeps track of the resources in your infrastructure and their current status. Produces output data (such as IP addresses and DNS names) for use in your workflows. Terraform Core is highly modular and flexible, allowing for extensibility and customizations through plugins and modules.

🚀 The Terraform Workflow 🚀

The Terraform workflow typically consists of the following three steps: Write, Review, and Apply. These steps allow you to define, plan, and execute changes to your infrastructure using Terraform.

📝 Step 1: Write 📝

In the first step of the Terraform workflow, you define your infrastructure resources and configurations using the HashiCorp Configuration Language (HCL). HCL is a domain-specific language that Terraform uses to describe the desired state of your infrastructure. You write Terraform configuration files (typically with a .tf extension) that specify the resources you want to create, configure, or manage. These configurations are stored in your project directory.

🏗️ Resource Definitions: In your configuration files, you define resources such as virtual machines, databases, networks, and any other infrastructure components that your application or system requires. You set attributes and properties for these resources, indicating how they should be provisioned.

🔧 Variables and Modules: You can use variables to parameterize your configurations, making them more reusable and flexible. Additionally, you may organize your configurations into modules, which are reusable, encapsulated building blocks for your infrastructure code.

🌐 Provider Configuration: Specify the cloud provider or service you want to use, and configure the provider with authentication details, region, and any other necessary settings.

🧩 Dependencies: Define relationships between resources to ensure they are created in the correct order. Terraform automatically determines the order of resource creation based on these dependencies.

📊 Step 2: Review 📊

Once you've written your Terraform configuration, it's time to review and plan the changes to your infrastructure. During this phase, Terraform performs several tasks to give you a clear view of the proposed changes:

🏗️ Initialization (terraform init): Before generating a plan, you need to initialize your working directory. This command downloads the necessary plugins and modules, sets up the state backend, and prepares Terraform for execution.

📈 Planning (terraform plan): This process step is essential to the workflow. After analyzing your configurations and comparing them to the infrastructure as it stands right now, It creates a thorough execution plan. The plan describes the adjustments Terraform will make to reach the intended state. It contains details on the addition, editing, and removal of resources.

🌐 Resource Graph: Terraform generates a dependency graph to determine the correct order in which resources should be created, modified, or destroyed. It ensures that dependencies are satisfied to maintain consistency.

🚦 Safety Precautions: Terraform performs a "dry run" during the planning phase. It doesn't actually change your infrastructure; instead, it gives you an idea of what's coming. This helps to identify potential issues and ensures that you are fully aware of the implications of carrying out the plan.

📋 Output Plan: You can review and confirm the suggested changes to display the execution plan in a human-readable format. The resources that will be updated, added, or removed are visible to you.

✅ Step 3: Apply ✅

The final step in the Terraform workflow is to apply the intended changes to your infrastructure. You can proceed to the "Apply" stage after reviewing and approving the execution plan:

🔨 Utilize (terraform apply): Using the terraform apply command, you can instruct Terraform to implement the changes listed in the execution plan. Terraform will start adding, deleting, or changing resources as needed.

🔵 Interactive Approval: Terraform will ask you to confirm through an interactive prompt when you wish to apply the plan. You have one more chance to review the modifications and indicate your explicit approval by typing "yes." Review the changes once more and express your explicit approval by typing "yes."

🔧 Creation and Modification of Resources: Terraform uses its APIs to interact with the corresponding cloud providers and services to provision.

🔌 2. How Terraform Providers Work

Suppliers of specific technologies are the second key component that powers Terraform. Typically, this role is filled by cloud service providers such as AWS or Azure, but any other infrastructure or platform as a service tool can be employed. For instance, Kubernetes would be considered a provider utilized by Terraform. It provides its resources to users through more than a hundred providers for various technologies. For example, if you use AWS, Terraform will have access to EC2 instances and other tech stack resources. Subsequently, you can construct infrastructure at multiple levels, such as by arranging Kubernetes on top of Azure.