Terraform

Terraform Introduction

Terraform is a tool for performing system provisioning
It uses HCL syntax (Hashicorp Configuration Language)

HCL (Hashicorp Configuration Language)

Terraform uses HCL for performing the provisioning type.

<block> <resource-type> <logical-name> {
    arg1 = value1
    arg2 = value2
}

The syntax is divided into

block: Block name defines the type of block

Resource-Type: Resource type is the predefined names for every resource. like "local_file", where $local$ defines the provider type which is local. $file$ define the resource.

Resource-name: It is the name of resource

arguments: All the arguments

For e.g.

Creating a file in local resource

resource "local_file" "basic_file" {
    filename = "/home/basic_file.txt"
    content = "This is a basic file created by Terraform"
}

AWS EC2 Instance provisioning

resource "aws_instance" "backendserver"{
    ami = "ami-10101010"
    instance_type = "t2.micro"
}

AWS S3 Bucket provisioning

resource "aws_s3_bucket" "doc_bucket" {
    bucket = "document_bucket_for_backend"
    acl = "private"
}


## Start provisioning

1. Initiate the provisioning 
```terraform
terraform init

This command check the configuration files
Initiate the working directory with name .terraform
Understand about the provider type and install essential plugins

Review the plan

terraform plan

This command will display the terraform action plan

Apply the changes

terraform apply

To show the resources

terraform show

To Destroy the complete provisioning

terraform destroy

Terraform Configuration file Structure

main.tf Main file contains resource configuration
variables.tf Contains variable declarations
outputs.tf Contains Outputs from Resources
provider.tf Contains Provider Definition

Multiple provider

To illustrate this,

lets make use of new provider "random"

To create random details we can use random as resource type

resource "random_pet" "my-employee" {
    prefix = "Mr."
    seperator = "."
    length = "1"
}

Defining the variables

Variable Syntax