[toc]

### Introduction to Infrastructure-as-Code

#### IaC tools/Software
:::warning
- Terraform (HCL)
- AWS CloudFormation (JSON/YAML)
- AWS CDK
- Azure ARM Templates
- HEAT templates (OpenStack)
- Pulumi
:::

### Introduction to Terraform

#### How Terraform works?


#### Terraform Workflow

:::warning
- terraform init
- terraform plan
- terraform apply
- terraform destroy
:::


### Installation and configuration

#### Installation steps (tested on Ubuntu 20.04):

wget -O- https://apt.releases.hashicorp.com/gpg | gpg --dearmor | sudo tee /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

Validation command:
terraform -v

Expected output:
Terraform v1.5.4
on linux_amd64

:mag: Above mentioned installation steps are for Ubuntu OS. For other Operating systems checkout the **[Terraform downloads](https://www.terraform.io/downloads)** page. Refer screenshots below:



#### Classroom activity (Update the Terraform version on Simplilearn lab machine)

Put installation commands in a small script:
## vi terra.sh

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


Make the script executable:
chmod +x terra.sh

Run the script:
sh terra.sh

Validation:
terraform -v

### Terraform Concepts

#### Terraform Commands

Initialize Terraform:
terraform init

Check if the config is right (dry run):
terraform plan

Create resources:
terraform apply

Create resources (auto approve):
terraform apply -auto-approve

Destroy resources:
terraform destroy # same as "terraform apply -destroy"

Additional Commands:
terraform show
terraform state
terraform fmt
terraform validate

#### Hashicorp Configuration Language


### References
:::info
- https://chocolatey.org/install
- https://developer.hashicorp.com/terraform/downloads
:::