Terraform

Terraform is an IaC software tool that provides a consistent command line interface (CLI) workflow to manage hundreds of cloud services. Terraform codifies cloud APIs into declarative configuration files.

Terraform is an open-source Infrastructure as Code (IaC) tool developed by HashiCorp. It allows users to define and provision infrastructure using a high-level configuration language known as HashiCorp Configuration Language (HCL) or JSON. Terraform supports a wide range of cloud providers, including AWS, Azure, Google Cloud Platform, and many on-premises solutions.

• Infrastructure as a code (IAC) codifies and manages underlying IT infrastructure as software
• Traditionally managing IT infrastructure was a manual and difficult process, person had to physically install and configure servers. It was expensive, slow and inconsistent.
• IaC enable the dev’s or operation team to automatically install, configure and manage infra.

Infrastructure as Code (IaC) offers several key advantages for organizations managing cloud and on-premises environments. Here are some of its primary benefits:

1. Consistency and Standardization: IaC ensures that infrastructure setups are consistent across different environments (development, testing, production) by using the same configuration files, reducing "environment drift."
2. Speed and Efficiency: Automated scripts for infrastructure setup replace manual processes, significantly speeding up deployment times. IaC allows teams to provision infrastructure in minutes instead of hours or days.
3. Version Control: Since IaC files are code, they can be stored in version control systems like Git, enabling tracking of infrastructure changes, rollback capabilities, and collaboration on infrastructure as if it were software code.
4. Reduced Costs: Automating infrastructure provisioning minimizes manual labor, reduces human error, and enables teams to use only what they need by automating infrastructure teardown. This reduces both time and costs.
5. Improved Security: IaC enables consistent implementation of security policies across environments. Configuration files can enforce compliance standards, helping to prevent misconfigurations and vulnerabilities.
6. Disaster Recovery: IaC makes infrastructure rebuilds and disaster recovery faster and more reliable, as it ensures that environments can be recreated automatically with minimal human intervention.
7. Scalability and Flexibility: IaC allows for easy scaling by defining infrastructure templates that can be adjusted to accommodate growing workloads, making it easier to scale resources up or down.
8. Enhanced Collaboration: IaC promotes DevOps practices by encouraging collaboration between development and operations teams, helping them to work together on shared infrastructure code and drive efficiencies.

Terraform and Declarative Language

Terraform is a declarative IaC tool that uses HCL (HashiCorp Configuration Language) to manage infrastructure. In Terraform:

• You define what resources you want (e.g., an EC2 instance in AWS, a network, a storage bucket) and specify their desired configurations.
• Terraform calculates the steps to take to reach that desired state, determining actions based on the current infrastructure and the state defined in the code.

This allows Terraform to handle changes efficiently. For example, if a change is made to an EC2 instance's size, Terraform only modifies that aspect without recreating the entire resource unless required.

Example Comparison

Suppose you want to create an EC2 instance.

Imperative Approach (e.g., using AWS CLI or scripts): You would manually run commands like these:

Declarative Approach (using Terraform): You’d define your desired state in a configuration file:

When you run terraform apply, Terraform will create or update the instance as needed, automatically managing dependencies and ensuring your infrastructure matches the desired state.

Imperative: How to do it, step-by-step instructions.

Declarative: What the final state should be, leaving the steps to the tool (like Terraform).

Uses of Terraform

Managing exiting infrastructure:

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Terraform is widely used for provisioning and managing new infrastructure, but it’s also powerful for managing existing infrastructure.

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• Terraform can import resources that were created manually or by other tools, bringing them under Terraform management. This lets you manage, modify, and track those resources without recreating them.

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• You can use the terraform import command to bring an existing resource (e.g., an EC2 instance) into Terraforms state file, which then allows it to be managed through Terraform configurations.

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After importing, you can define the resource in Terraform configuration files to align its state and manage it within Terraform.

Creating new infrastructure:

Terraform is widely used to create new infrastructure in an efficient, repeatable, and automated way. Here are keyways Terraform can be leveraged when provisioning new infrastructure:

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• Terraform allows you to define infrastructure as code in configuration files. These configurations specify the details of resources to create, such as virtual machines, networks, databases, and storage.
• Running terraforms apply automatically provisions resources based on the configuration, enabling a consistent and automated setup of complex environments.

Example

Terraform Architecture

Terraform is an open-source Infrastructure as Code (IaC) tool that allows you to define, provision, and manage infrastructure across multiple cloud providers and services. Its architecture is based on a modular, declarative approach, where the desired infrastructure state is defined in configuration files, which Terraform uses to orchestrate the deployment and lifecycle of resources. Here's an overview of Terraform's architecture:

1. Core Components of Terraform Architecture

• Configuration Files: Written in HashiCorp Configuration Language (HCL) or JSON, configuration files define the desired infrastructure state. These files describe resources such as virtual machines, networks, storage, and databases, as well as their relationships.
• Terraform Core: The core is responsible for managing the Terraform run workflow, including parsing configuration files, planning the infrastructure changes, and applying those changes. It performs two main functions:

Reading configuration files to build a resource dependency graph.

Executing a plan to compare the desired state (defined in configuration files) with the current state, and determining the necessary actions.

• Providers: Providers are plugins that Terraform uses to interact with APIs from cloud providers (like AWS, Azure, GCP) or other services (like GitHub, Kubernetes, or Datadog). Each provider is responsible for translating the HCL configuration into specific API calls. Providers are developed and maintained either by HashiCorp or the community.
• State Management: Terraform maintains a state file (terraform.tfstate) that keeps track of the real-time state of resources managed by Terraform. This state file is used by Terraform to understand what resources it manages and to determine changes to apply. It can be stored locally or remotely (e.g., in an S3 bucket, HashiCorp Consul, or Terraform Cloud) for collaboration and data security.
• Provisioners: Provisioners allow running scripts or commands on a resource after it's created. For example, you can use provisioners to configure resources or perform post-deployment tasks. While provisioners should be used sparingly in production (they introduce procedural steps into a declarative workflow), they can be useful for bootstrapping configurations.

2. Terraform Workflow

The Terraform workflow generally follows these steps:

• Write: Create or update configuration files that define the infrastructure in a declarative manner.
• Plan: Terraform evaluates the current state and compares it with the configuration to display the changes it will make. This plan provides visibility into what will change before any modifications are applied.
• Apply: After reviewing the plan, you apply the changes to deploy or modify the infrastructure.
• Destroy: Terraform can also remove resources it has created if they are no longer needed. This is often used for tearing down environments.

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3. State Management & Backend Configuration

Terraform uses a state file to keep track of the resources it manages. This state file can be configured to use various backends, including:

• Local Backend: Stores the state file locally, suitable for single-user scenarios.
• Remote Backends: Stores the state in a shared location like AWS S3, Terraform Cloud, HashiCorp Consul, or a remote database. This setup enables collaboration and locks the state file during changes to prevent conflicts.

4. Modules

Modules are reusable configurations that encapsulate a group of resources defined together. They allow you to abstract, reuse, and share common configurations across different projects or teams.

5. Terraform Cloud & Enterprise

Terraform Cloud and Enterprise versions add advanced features such as remote execution, private module registries, team collaboration, role-based access control, and integration with version control systems (VCS) for Continuous Integration/Continuous Deployment (CI/CD) workflows.

6. Execution Flow

1. Init: Initializes the working directory, downloads providers, and sets up the backend.
2. Plan: Creates an execution plan based on the configuration and current state.
3. Apply: Executes the planned actions to reach the desired state.
4. Destroy: Removes all resources created by the configuration.

Download and install Terraform for Windows

1. Download the terraform ZIP file from Terraform site. Install | Terraform | HashiCorp Developer
2. Extract the .exe from the ZIP file to a folder eg C:\Apps\Terraform copy this path location like C:\Apps\terraform\
3. Add the folder location to your PATH variable, eg:?Control Panel -> System -> System settings -> Environment Variables
4. In?System Variables, select?Path?>?edit?>?new?> Enter the location of the Terraform.exe, eg?C:\Apps\Terraform?then click?OK

Open a new CMD/PowerShell and the Terraform command should work