DevOps Classroom notes 14/Sep/2024

Infrastructure as Code w.r.t Infra Provisioning

• Infrastructure as a code (IAC) is a concept where you express your infrasturcture in a declarative way
• We need to express
  • What we want to create/manage (Resource)
  • Outputs
• Tools
  • AWS: Cloud formation
  • Azure: ARM Templates, Bicep
  • Terraform (open tofu): Almost any virtual environments
  • Pulumi

Three tier architecture

• Lets look at a simple 3-tier architecture (Web sites)
  
• The infrastructure to run the above app is
  • Network
  • Servers (Linux/Windows)
  • Public ip
  • DNS (optional)
• The application deployment will be possible when this infrastructure is ready
• Deploying application involves
  • running some commands on each server to install and configure applications
• Terraform is used for Infra creation

Other areas to consider

• Terraform will create infra which is virtual in nature.
• Virtual infra can be created
  • onpremises
    • Hypervisors (Vmware)
    • Private Cloud (Openstack)
  • cloud
    • Azure
    • AWS
    • GCP
• We need to provide information to Terraform where to create infra and pass credentials
• Conceptually this is called as Provider in Terraform

Complications in Three Tier after running our application in production

• To address the increasing needs of your applications we have to do scaling
  • Vertical Scaling: Increasing the resources of the same server
  • Horizontal Scaling: Increasing number of servers
• For this every cloud offers auto scaling
  • AWS => auto scaling group
  • GCP => INstance Groups
  • Azure => Virtual machine scale sets

Terraform components (So far)

• Provider
• Resource
  

How Terraform Works

• Terraform is developed in Google Go language
• Terraform is a single executable.
• Terraform can interact with specific providers (AWS, Azure, Vmware) to create/manage infrastructure Refer Here
• Each Provider will have lots of resources which we can define to create infra.
• What terraform can do is (as of our understanding)
  • init (initialize => downloading providers)
  • apply (create/update infra)
  • destroy (delete infrawork)

Template

• In terraform we need to express infrastucture in a declartive fashion and what we create is called as template.
• Terraform takes a folder as input considering all .tf files a folder

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
      version = "5.67.0"
    }
  }
}

provider "aws" {
  # Configuration options
  region = "ap-south-1"
}


resource "aws_vpc" "base" {
    cidr_block = "10.100.0.0/16"
    tags = {
        Name = "from devops team"
    }
}