Terraform Introduction

What is Terraform

Terraform is an open-source infrastructure as code software tool created by HashiCorp. It enables users to define and provision a datacenter infrastructure using a high-level configuration language known as Hashicorp Configuration Language (HCL), or optionally JSON.

Why Terraform

Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently. Terraform can manage existing and popular service providers as well as custom in-house solutions.

Configuration files describe to Terraform the components needed to run a single application or your entire datacenter. Terraform generates an execution plan describing what it will do to reach the desired state, and then executes it to build the described infrastructure. As the configuration changes, Terraform is able to determine what changed and create incremental execution plans which can be applied.

Provider Superpowers

Terraform's providers are like magical gateways to cloud and infrastructure platforms. With providers for AWS, Azure, Google Cloud, and more, you can seamlessly interact with your chosen realm. Configuration is your key to these gateways.

Resource

Resources in Terraform are your building blocks. Whether it's virtual machines, databases, networks, or storage, Terraform can sculpt them all. Each resource is a canvas for your creativity, defined in code.

Module Magic

Think of modules as spells in your Terraform spellbook. They encapsulate configurations, making them reusable across your mystical infrastructure. Modules can be your creations or borrowed from the Terraform Registry, a treasure trove of community-contributed wonders.

Configuration

Terraform thrives on configuration files, often donning the .tf cape. These files define your desired infrastructure state, housing providers, resources, variables, and more. The main.tf file, your trusty sidekick, takes the lead, but you can have an ensemble of supporting files.

Variable Versatility

Variables in Terraform are the chameleons of your code. They adapt to different environments, allowing you to define values outside your code and infuse them when you weave Terraform's magic.

Output Illumination

Outputs shine as the results of your Terraform sorcery. They reveal information and can pass values to other parts of your enchanting infrastructure.

State Management

Terraform's state file is your spellbook, containing the current state of your infrastructure. It's essential for Terraform to decipher what's been conjured and what changes await in its mystical updates.

Plan

Before Terraform takes action, it offers a glimpse of the future with a plan. The terraform plan command foretells the changes Terraform will enact during the apply step.

Apply

Terraform's apply command brings your code to life. It creates, updates, or banishes resources according to your configuration's spells.

Workspace Realms

Workspaces in Terraform are like parallel universes, each housing its own configuration and state. They're perfect for managing distinct environments like development, staging, and production, keeping your magic organized and separate.

Remote Enchantment

Remote backends, such as Amazon S3 or Terraform Cloud, are like secret vaults for your state files, enhancing security and collaboration by keeping your magical records safe beyond your local realm.

Installation Process

To install Terraform on your machine. The installation process is simple and straightforward. Here are the steps:

1. Visit the official Terraform website (https://www.terraform.io/).

2. Download the Terraform binary for your operating system.

3. Extract the downloaded archive to a directory in your system's PATH.

4. Verify the installation by running terraform version in your terminal. If it responds with the version number, you're ready to cast your first spell.

Terraform Commands

Terraform is a command-line tool, so you'll be using your terminal or command prompt to interact with it. The commands are simple and easy to learn. Here are the most common ones:

• terraform init initializes a working directory containing Terraform configuration files.

• terraform plan creates an execution plan.

• terraform apply executes the actions proposed in a Terraform plan.

• terraform destroy destroys all resources created by Terraform.

• terraform validate validates the configuration files in a directory, referring only to the configuration and not accessing any remote services such as remote state, provider APIs, etc.

• terraform fmt formats the configuration files in a directory to the Terraform coding style.

• terraform get downloads and installs modules needed for the configuration in a directory.

• terraform graph creates a visual representation of the configuration or execution plan.

• terraform output displays the outputs of a Terraform configuration.

• terraform show inspects the current state or a saved plan.

• terraform taint manually marks a Terraform-managed resource as tainted, forcing it to be destroyed and recreated on the next apply.

• terraform untaint manually unmarks a Terraform-managed resource as tainted.

• terraform workspace manages workspaces (e.g. terraform workspace list).

Terraform Configuration Files

Terraform configuration files are your spells. They're written in HashiCorp Configuration Language (HCL), a declarative language that describes your desired infrastructure state. The files are usually named main.tf, variables.tf, and outputs.tf, but you can have as many as you want.

main.tf

The main.tf file is the main configuration file. It's where you define your resources, variables, and other settings. It's the only required file in a Terraform configuration.

variables.tf

The variables.tf file is where you define your variables. Variables are like placeholders for your values. They're useful for reusing values across your configuration and keeping sensitive data out of your code.

outputs.tf

The outputs.tf file is where you define your outputs. Outputs are like the return values of your configuration. They're useful for passing information to other parts of your infrastructure.

Terraform Resources

Resources are the building blocks of your infrastructure. They're the most important element in your Terraform configuration. They're defined in the main.tf file using the following syntax:

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

The above code creates an AWS EC2 instance. The first line defines the resource type, aws_instance, and the resource name, example. The second line defines the resource arguments, ami and instance_type. The arguments are used to configure the resource.

Terraform Providers

Providers are the gateways to your infrastructure. They're the second most important element in your Terraform configuration. They're defined in the main.tf file using the following syntax:

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

The above code configures the AWS provider to use the us-east-1 region. The provider name is aws. The provider arguments are region. The arguments are used to configure the provider.

Terraform Variables

Variables are like the chameleons of your code. They adapt to different environments, allowing you to define values outside your code and infuse them when you weave Terraform's magic. They're defined in the variables.tf file using the following syntax:

variable "region" {
  type    = string
  default = "us-east-1"
}

The above code defines a variable named region. The variable type is string. The variable default value is us-east-1. The variable is used to configure the provider.

Terraform Outputs

Outputs are like the return values of your configuration. They're useful for passing information to other parts of your infrastructure. They're defined in the outputs.tf file using the following syntax:

output "region" {
  value = aws_instance.example.region
}

The above code defines an output named region. The output value is aws_instance.example.region. The output is used to display the region of the aws_instance resource.

Terraform State

Terraform's state file is your spellbook, containing the current state of your infrastructure. It's essential for Terraform to decipher what's been conjured and what changes await in its mystical updates. The state file is named terraform.tfstate. It's created automatically when you run terraform apply. It's usually stored locally, but it can be stored remotely in a backend like Terraform Cloud.

Terraform Modules

Modules are like spells in your Terraform spellbook. They encapsulate configurations, making them reusable across your mystical infrastructure. Modules can be your creations or borrowed from the Terraform Registry, a treasure trove of community-contributed wonders. They're defined in the main.tf file using the following syntax:

module "vpc" {
  source = "terraform-aws-modules/vpc/aws"
  version = "2.21.0"
  name = "my-vpc"
  cidr = "" 
}

The above code creates an AWS VPC module. The module name is vpc. The module source is terraform-aws-modules/vpc/aws. The module version is 2.21.0. The module arguments are name and cidr. The arguments are used to configure the module.

Terraform Workspaces

Workspaces in Terraform are like parallel universes, each housing its own configuration and state. They're perfect for managing distinct environments like development, staging, and production, keeping your magic organized and separate. They're managed using the terraform workspace command. Here are the most common commands:

• terraform workspace new creates a new workspace.

• terraform workspace list lists all workspaces.

• terraform workspace select selects a workspace.

• terraform workspace show shows the current workspace.

• terraform workspace delete deletes a workspace.

Terraform Backends

Remote backends, such as Amazon S3 or Terraform Cloud, are like secret vaults for your state files, enhancing security and collaboration by keeping your magical records safe beyond your local realm. They're defined in the main.tf file using the following syntax:

terraform {
  backend "s3" {
    bucket = "my-bucket"
    key    = "path/to/my/key"
    region = "us-east-1"
  }
}

The above code configures the S3 backend to use the my-bucket bucket in the us-east-1 region. The backend name is s3. The backend arguments are bucket, key, and region. The arguments are used to configure the backend.

Terraform Graph

Terraform's graph command creates a visual representation of the configuration or execution plan. It's useful for understanding complex configurations. It's used with the terraform graph command. Here are the most common commands:

• terraform graph creates a visual representation of the configuration or execution plan.

• terraform graph | dot -Tsvg > graph.svg creates a visual representation of the configuration or execution plan in SVG format.

Terraform Plan

Before Terraform takes action, it offers a glimpse of the future with a plan. The terraform plan command foretells the changes Terraform will enact during the apply step. It's used with the terraform plan command. Here are the most common commands:

• terraform plan creates an execution plan.

• terraform plan -out=plan.tf creates an execution plan and saves it to a file.

• terraform plan -destroy creates a destruction plan.

• terraform plan -destroy -out=plan.tf creates a destruction plan and saves it to a file.

Terraform Apply

Terraform's apply command brings your code to life. It creates, updates, or banishes resources according to your configuration's spells. It's used with the terraform apply command. Here are the most common commands:

• terraform apply executes the actions proposed in a Terraform plan.

• terraform apply plan.tf executes the actions proposed in a Terraform plan file.

• terraform apply -auto-approve executes the actions proposed in a Terraform plan without asking for confirmation.

• terraform apply -target=aws_instance.example executes the actions proposed in a Terraform plan, targeting a specific resource.

• terraform apply -var="region=us-east-1" executes the actions proposed in a Terraform plan, overriding a variable.

• terraform apply -var-file="dev.tfvars" executes the actions proposed in a Terraform plan, overriding variables with a file.

• terraform apply -var="region=us-east-1" -var-file="dev.tfvars" executes the actions proposed in a Terraform plan, overriding variables with a file and a command-line argument.

Terraform Destroy

Terraform's destroy command destroys all resources created by Terraform. It's used with the terraform destroy command. Here are the most common commands:

• terraform destroy destroys all resources created by Terraform.

• terraform destroy -auto-approve destroys all resources created by Terraform without asking for confirmation.

• terraform destroy -target=aws_instance.example destroys a specific resource created by Terraform.

• terraform destroy -var="region=us-east-1" destroys all resources created by Terraform, overriding a variable.

• terraform destroy -var-file="dev.tfvars" destroys all resources created by Terraform, overriding variables with a file.

• terraform destroy -var="region=us-east-1" -var-file="dev.tfvars" destroys all resources created by Terraform, overriding variables with a file and a command-line argument.

Terraform Validate

Terraform's validate command validates the configuration files in a directory, referring only to the configuration and not accessing any remote services such as remote state, provider APIs, etc. It's used with the terraform validate command. Here are the most common commands:

• terraform validate validates the configuration files in a directory, referring only to the configuration and not accessing any remote services such as remote state, provider APIs, etc.

• terraform validate -json validates the configuration files in a directory, referring only to the configuration and not accessing any remote services such as remote state, provider APIs, etc., and outputs the result in JSON format.

Terraform Fmt

Terraform's fmt command formats the configuration files in a directory to the Terraform coding style. It's used with the terraform fmt command. Here are the most common commands:

• terraform fmt formats the configuration files in a directory to the Terraform coding style.

• terraform fmt -recursive formats the configuration files in a directory and its subdirectories to the Terraform coding style.

Terraform Get

Terraform's get command downloads and installs modules needed for the configuration in a directory. It's used with the terraform get command. Here are the most common commands:

• terraform get downloads and installs modules needed for the configuration in a directory.

• terraform get -update downloads and installs modules needed for the configuration in a directory, including modules that are already downloaded.

Terraform Show

Terraform's show command inspects the current state or a saved plan. It's used with the terraform show command. Here are the most common commands:

• terraform show inspects the current state or a saved plan.

• terraform show -json inspects the current state or a saved plan and outputs the result in JSON format.

Terraform Taint

Terraform's taint method can be used to perform a manual taint of a resource. It's used with the terraform taint command. Here are the most common commands:

• terraform taint manually marks a Terraform-managed resource as tainted, forcing it to be destroyed and recreated on the next apply.

Terraform Untaint

Terraform's untaint method can be used to perform a manual untaint of a resource. It's used with the terraform untaint command. Here are the most common commands:

• terraform untaint manually unmarks a Terraform-managed resource as tainted.

Terraform Output

Terraform's output command displays the outputs of a Terraform configuration. It's used with the terraform output command. Here are the most common commands:

• terraform output displays the outputs of a Terraform configuration.

• terraform output -json displays the outputs of a Terraform configuration in JSON format.