Terraform Basics.txt

Terraform Basics
-----------------

- Allows me to write infrastructure-as-code
- Automation of my infrastructure
- Keep infrastructure in a certain state (e.g no less than 3 instances open)
- Make my infrastructure auditable
- Keep in versional control
- Ansible, Chef, Puppet focus on automating and config of "software"
- Terrafom focuses on "infrastructure"
- Works well with automation software like ansible to install software "after" the infrastructure
is provisioned
- Works with multiple cloud providers

$ terraform version
$ terraform init // run in new directory with your terraform file before you run "apply"
$ terraform validate // validates terraform files
$ terraform apply
$ terraform destroy // destroys the apply that you ran
$ terraform plan // show you the changes that your terraform file would make if applied
$ terraform plan -out tfplan // safe way to print the changes that are going to be made 
$ terraform apply tfplan // changes that are going to be executed
$ terraform console // starts interactive console to evaluate expressions based on created objects

Make a directory for your terraform files
  mkdir -p /terraform
  cd /terraform

Create a terraform script
  vim main.tf
  
  provider "aws" {
  access_key = "xxxxxx"
  secret_key = "xxxxxx"
  region     = "us-east-1"
}

// "resource_type" "resource_name"
resource "aws_instance" "example" {  
  ami           = "ami-011b3ccf1bd6db744"
  instance_type = "t2.micro"
  subnet_id = "subnet-ad7da4e7"
  vpc_security_group_ids = ["sg-0ac5e15ddfe7cefe0"]
  key_name = "macKey"
  tags = {
    Name = "Terraform 1"
  }
}
output "ip"{
  value = "${aws_instance.example.public_ip}"
}

Initialize Terraform
  terraform init

Validate files
  terraform validate
 
 List providers in the folder
   ls .terraform/plugins/linux_amd64
 
 List providers in the folder
   terraform providers
   
 Generate execution plan and send to outfile
   terraform plan -out=tfplan
   
 Execute the plan
   terrafrom apply tfplan
  
  Show state
    terraform show
  
 Start Terraform Console and Get Resource Property Values
   terraform console
   > aws_instance.example.ami
   > aws_instance.example.instance_type