madhank93 / learn-tf

What is Terraform ?

It is an open source Infrastructure as Code (IAC) tool to automate and manage your infrastructure.

Configuration Management vs Infrastructure Provisioning tool

Configuration Management	Infrastructure Provisioner
Primarily designed to install and manage software on existing servers	Primarily provisions the servers and infrastructures
Popular tools - Ansible, Chef and Salt stack	Popular tools - Terraform and Pulumi

Note Please look at the index file for easier navigation and better overview of the project.

1. What are the main commands available in Terraform ?

   - **init** - To initialize a terraform files - **validate** - Checks wether tf files are syntactically valid - **plan** - Shows preview changes required by the current configuration - **apply** - Executes the plan by creating or updating infra - **destroy** - Deletes previously created resource - **refresh** - Queries infrastructure to get current state - **fmt** - Rewrites all Terraform configuration files to a canonical format. (Includes - `.tf` and `.tfvars` but not the `.tf.json` or `.tfvars.json`)

2. What is the structure of the terraform file ?

   Syntax:

   <block-name> <resource-type> <resource-name> {
       argument = value # could be an optional or mandatory argument
       argument = value
   }

   Resource block:

   resource "aw_iam_user" "admin-user" {
       name = "lucy"
       tags = {
         Description = "TL for the sapphire project"
       }
   } 

   Data block:

   data "aws_ami" "example" {
     most_recent = true
   
     owners = ["self"]
     tags = {
       Name   = "app-server"
       Tested = "true"
     }
   }