day-22

TERRAFORM LOCALS: its a block used to define values
once you define a value on this block you can use them multiple times
changing the value in local block will be replicated to all resources.
simply define value once and use for mutiple times.


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


locals {
env = "${terraform.workspace}"
}

resource "aws_vpc" "one" {
cidr_block = "10.0.0.0/16"
tags = {
Name = "${local.env}-vpc"
}
}

resource "aws_subnet" "two" {
vpc_id = aws_vpc.one.id
cidr_block = "10.0.0.0/24"
tags = {
Name = "${local.env}-subnet"
}
}

resource "aws_instance" "three" {
  subnet_id = aws_subnet.two.id
  ami           = "ami-079db87dc4c10ac91"
  instance_type = "t2.micro"
  tags = {
    Name = "${local.env}-server"
  }
}


s3 Backend setup: 
it will store terraform statefile in bucket.
when we modify the infra it will update the statefile in bucket.

why: state file is very imp in terraform
without state file we cant track the infra
if you lost it we cant manage the infra

backup file is a backup of the terraform. tfstate file. Terraform automatically creates a backup of the state file before making any changes to the state file. This ensures that you can recover from a corrupted or lost state file.


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

terraform {
  backend "s3" {
    bucket = "swiggyterraformbucket001"
    key    = "terraform.tfstate"
    region = "us-east-1"
  }
}

locals {
env = "${terraform.workspace}"
}

resource "aws_vpc" "one" {
cidr_block = "10.0.0.0/16"
tags = {
Name = "${local.env}-vpc"
}
}

resource "aws_subnet" "two" {
vpc_id = aws_vpc.one.id
cidr_block = "10.0.0.0/24"
tags = {
Name = "${local.env}-subnet"
}
}

resource "aws_instance" "three" {
  subnet_id = aws_subnet.two.id
  ami           = "ami-079db87dc4c10ac91"
  instance_type = "t2.micro"
  tags = {
    Name = "${local.env}-server"
  }
}


TERRAFORM TAINT & UNTAINT: 
it is used to recreate specific resources in infrastructure.
Why: 
if i have an ec2 -- > crashed
ec2 -- > code -- > main.tf 
now to recreate this ec2 seperately we need to taint the resource

terraform state list
terraform taint aws_instance.three
terraform apply --auto-approve

TO TAINT: terraform taint aws_instance.three
TO UNTAINT: terraform untainted aws_instance.three



META ARGUMENTS:

PREVENT DESTROY:

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


locals {
  env = terraform.workspace
}

resource "aws_vpc" "one" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "${local.env}-vpc"
  }
}

resource "aws_subnet" "two" {
  vpc_id     = aws_vpc.one.id
  cidr_block = "10.0.0.0/24"
  tags = {
    Name = "${local.env}-subnet"
  }
}

resource "aws_instance" "three" {
  subnet_id     = aws_subnet.two.id
  ami           = "ami-079db87dc4c10ac91"
  instance_type = "t2.micro"
  tags = {
    Name = "${local.env}-server"
  }
  lifecycle {
    prevent_destroy = false
  }
}


IGNORE CHANGES:

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


locals {
  env = terraform.workspace
}

resource "aws_vpc" "one" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "${local.env}-vpc"
  }
}

resource "aws_subnet" "two" {
  vpc_id     = aws_vpc.one.id
  cidr_block = "10.0.0.0/24"
  tags = {
    Name = "${local.env}-subnet"
  }
}

resource "aws_instance" "three" {
  subnet_id     = aws_subnet.two.id
  ami           = "ami-079db87dc4c10ac91"
  instance_type = "t2.micro"
  tags = {
    Name = "${local.env}-server"
  }
  lifecycle {
    ignore_changes = [
      tags,
    ]
  }
}


DEPENDS ON:
provider "aws" {
  region = "us-east-1"
}


locals {
  env = terraform.workspace
}



resource "aws_instance" "three" {
  ami           = "ami-079db87dc4c10ac91"
  instance_type = "t2.micro"
  tags = {
    Name = "${local.env}-server"
  }
    depends_on = [
      aws_vpc.one
    ]
}

HISTORY:
  102  rm -rf test.tfvar dev.tfvar variable.tf
  103  vim main.tf
  104  terraform init
  105  vim main.tf
  106  terraform init
  107  vim main.tf
  108  terraform init
  109  terraform plan
  110  terraform apply --auto-approve
  111  vim main.tf
  112  terraform apply --auto-approve
  113  vim main.tf
  114  terraform apply --auto-approve
  115  terraform workspace new test
  116  vim main.tf
  117  terraform apply --auto-approve
  118  terraform workspace new prod
  119  terraform apply --auto-approve
  120  terraform workspace select test
  121  terraform destroy --auto-approve
  122  terraform workspace select default
  123  terraform workspace delete prod
  124  terraform workspace delete test
  125  terraform state list
  126  terraform graph
  127  cat main.tf
  128  terraform destroy --auto-approve
  129  vim main.tf
  130  terraform apply --auto-approve
  131  terraform init
  132  terraform apply --auto-approve
  133  ll
  134  cat terraform.tfstate
  135  cat terraform.tfstate.backup
  136  du -sh  terraform.tfstate.backup
  137  terraform state list
  138  terraform destroy --auto-approve -target="aws_instance.three"
  139  du -sh  terraform.tfstate.backup
  140  terraform refresh
  141  du -sh  terraform.tfstate.backup
  142  cat terraform.tfstate
  143  cat terraform.tfstate.backup
  144  cat main.tf
  145  vim main.tf
  146  terraform apply --auto-approve
  147  terraform init -migrate-state
  148  terraform apply --auto-approve
  149  ll
  150  cat terraform.tfstate
  151  terraform state list
  152  terraform taint aws_instance.three
  153  terraform apply --auto-approve
  154  terraform taint aws_instance.three
  155  terraform taint aws_subnet.two
  156  terraform untaint aws_subnet.two
  157  terraform untaint aws_instance.three
  158  vim main.tf
  159  terraform destroy --auto-approve \
  160  terraform destroy --auto-approve
  161  terraform state list
  162  ll
  163  cd terraform/
  164  terraform destroy --auto-approve
  165  vim main.tf
  166  terraform destroy --auto-approve
  167  ll
  168  terraform state list
  169  vim main.tf
  170  terraform fmt
  171  vim main.tf
  172  terraform apply --auto-approve
  173  cat terraform.tfstate | grep -i Name
  174  terraform refresh
  175  cat terraform.tfstate | grep -i Name
  176  vim main.tf
  177  terraform apply --auto-approve
  178  cat terraform.tfstate | grep -i Name
  179  terraform refresh
  180  cat terraform.tfstate | grep -i Name
  181  terraform destroy --auto-approve
  182  terraform apply --auto-approve
  183  cat main.tf
  184  cat terraform.tfstate | grep -i Name
  185  terraform refresh
  186  cat terraform.tfstate | grep -i Name
  187  terraform refresh
  188  cat terraform.tfstate | grep -i Name
  189  terraform destroy --auto-approve
  190  vim main.tf
  191  terraform fmr
  192  terraform fmt
  193  vim main.tf
  194  terraform apply --auto-approve
  195  vim main.tf
  196  terraform apply --auto-approve
  197  vim main.tf
  198  terraform apply --auto-approve
  199  vim main.tf
  200  history