Terraweek Day -1 : Introduction to Terraform and Terraform Basics

What is Terraform and how can it help you manage infrastructure as code?

Terraform is an open-source infrastructure as code (IaC) tool developed by HashiCorp. It helps you manage and provision your cloud resources and infrastructure by defining them in code, which is often referred to as "Infrastructure as Code" (IaC). you can use it to manage resources in various cloud providers, on-premises data centers, and other infrastructure platforms. Operators and Infrastructure teams can use Terraform to manage environments with a configuration language called the HashiCorp Configuration Language (HCL) for human-readable, automated deployments. Here's a simple explanation of how Terraform can help:

1. Declarative Infrastructure: With Terraform, you describe your desired infrastructure in a declarative configuration file. This file outlines what resources you need (e.g., virtual machines, databases, networks), how they should be configured, and their relationships.
  1. Cross-Platform Compatibility: Terraform supports multiple cloud providers (e.g., AWS, Azure, Google Cloud), as well as on-premises infrastructure and various services and resources within them.
  2. Automation: Once you've defined your infrastructure in Terraform code, you can use Terraform commands to automatically create, update, or delete resources. This streamlines the process and reduces human error.
  3. Version Control: Terraform code can be stored in version control systems like Git, enabling collaboration, tracking changes, and rolling back to previous infrastructure states if needed.
  4. Dependency Management: Terraform automatically manages dependencies between resources. It ensures that resources are provisioned in the correct order, reducing the complexity of managing complex infrastructures.
  5. Plan and Preview: Terraform provides a "plan" feature that shows you what changes will be applied to your infrastructure before actually making them. This helps prevent unintended consequences and allows you to review and approve changes.
  6. State Management: Terraform keeps track of the current state of your infrastructure in a state file. This enables it to determine what changes are necessary to bring the actual infrastructure in line with the desired state.
  7. Modularity and Reusability: Terraform encourages the use of modules, which are reusable and shareable pieces of configuration. This promotes modularity and consistency in your infrastructure code.

Why do we need Terraform and how does it simplify infrastructure provisioning?

Terraform simplifies infrastructure provisioning by automating tasks, leveraging code-based configurations, supporting multi-cloud environments, providing consistency, managing infrastructure state, handling dependencies, and offering preview capabilities for change validation. you can overcome the challenges of slow deployment, high costs, limited automation, human errors, and resource wastage in your infrastructure provisioning process, resulting in more efficient and reliable infrastructure management.

Here are the reasons why we need Terraform and how it simplifies infrastructure provisioning:

Infrastructure as Code: Defines and manages infrastructure using code, facilitating versioning and collaboration.
Automation: Enables automated infrastructure provisioning, reducing manual effort.
Multi-Cloud Support: Works with various cloud providers, simplifying management in multi-cloud or hybrid cloud environments.
Infrastructure State Management: Keeps track of the infrastructure state, making it easier to update and modify resources.
Dependency Management: Automatically manages resource dependencies, ensuring the correct order of operations.
Plan and Preview: Generates execution plans for changes, allowing review before applying them.

How can you install Terraform and set up the environment for AWS, Azure, or GCP?

To install Terraform and set up the environment for AWS, follow the below steps:

Install Terraform

You can install Terraform from official Terraform website: terraform.io

Run these commands to install Terraform on your local system. For Ubuntu, we can use these commands or if you are using any other OS then visit this link

     wget -O- https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg
     echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
     sudo apt update && sudo apt install terraform

To verify the installation, run the following command in the terminal.
```
     terraform version
```

Set up AWS Credentials

Navigate to the IAM console, and click on "Users".
Click on the "Add user" button to create a new IAM user.
Enter name and click on next.

we can assign policies to the user. Select the appropriate policies.
- Review the user's configuration details and click on "Create user" to create the IAM user.
- After the user is created click on the security credentials tab of the user.
- Click on create an access key.
  
  Select CLI and click on next.
- Access keys and secrets are generated, copy from here and download as well.
  
  Configure AWS Credentials for Terraform
  - Open a terminal or command prompt.
  - Run the following command to configure the AWS credentials.
```
   aws configure
```
  - Enter the access key and secret access key which generated in the previous step.
  - Specify the default region (e.g., ap-south-1)
    
    Create a Terraform Configuration File
    - Create a new directory for your Terraform project(Here I am using ubuntu linux).
    - Inside the project directory, create a file named main.tf (or any other name with a .tf extension).
    - In the main.tf file, write Terraform configurations.

Initialize and Apply Terraform Configuration

Open a terminal or command prompt in the project directory.
Run the following command to initialize Terraform and download the necessary provider plugins.
```
    terraform init
```

After initialization, run the following command to preview the changes Terraform will make to your infrastructure.

          terraform plan

plan looks good, apply the changes by running the following command.
```
    terraform apply
```
Confirm the changes by typing yes.
Terraform will provision the specified AWS resources based on the configuration.

To destroy the structure use the below commands.
```
    terraform destroy
```

Explain the important terminologies of Terraform with the example of at least (5 crucial terminologies).

These crucial terminologies in Terraform provide the foundation for defining, provisioning, and managing infrastructure as code. Understanding these terms is essential for effectively using Terraform to automate and manage your infrastructure.

Provider: A provider is responsible for managing and interacting with a specific infrastructure platform, such as AWS, Azure, or Google Cloud Platform. It allows Terraform to create, update, and delete resources within that platform.
```
  provider "aws" {
    region = "ap-south-1"
  }
```
Resource: A resource represents a single infrastructure object, such as a EC2, S3 or database, that Terraform manages within a provider. Each resource has a specific type and configuration settings.
```
  resource "aws_instance" "demo-ec2" {
    ami           = "ami-0f5ee92e2d63afc18"
    instance_type = "t2.micro"
  }
```
Module: A module is a reusable set of Terraform configurations that encapsulates a specific piece of infrastructure. It allows you to abstract complex configurations into a single component that can be used across projects or shared with others.
```
  module "vpc" {
    source  = "terraform-aws-modules/vpc/aws"
    version = "3.0.0"

    name = "my-vpc"
    cidr = "10.0.0.0/16"
  }
```

Variable: A variable allows you to parameterize your Terraform configurations, making them flexible and reusable. Variables can be assigned values from various sources and passed into modules or used within configurations.

  variable "instance_count" {
    type    = number
    default = 1
  }

  resource "aws_instance" "example" {
    count          = var.instance_count
    instance_type  = "t2.micro"
    ami            = "ami-0c94855ba95c71c99"
  }

5. State: State is useful to keep a record of why and how infrastructure was created at the first place. It is Used to improve performance, dependency management,Terraform automatically creates and manages the state file for you. The state file keeps track of the current state of your infrastructure, including the resources you've defined and their attributes.