/Terraform_multiple_modules

Primary LanguageHCL

How to work with multiple terraform modules?

What is Terraform?

Terraform is a free and open-source infrastructure as code (IAC) that can help to automate the deployment, configuration, and management of the remote servers. Terraform can manage both existing service providers and custom in-house solutions.

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Prerequisites:

  • A server that has Terraform installed in it & AWS CLI also!
  • Basic understanding of Terraform
  • Basic understanding of AWS
  • AWS Access Key & Secret Key

What are terraform modules?

A Terraform module allows you to create logical abstraction on the top of some resource set. In other words, a module allows you to group resources together and reuse this group later, possibly many times. Terraform module allow us to use the concept of DRY (Don't Repete Yourself). With the use of terraform modules you can write the code for various resources once and reuse them in different environment as per your need!

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You can read more details of terraform modules from here

In this tutorial we will take a look at how to use modules and maintain different infrastructure for different environment!

Step 1:

  • We need to create the moduel for VPC so that we can use it for different environment later!

  • Create a folder called modules and vpc inside modules folder

    VW3N7VQKQX:Terraform_multiple_modules dhruvins$ cd modules/
VW3N7VQKQX:modules dhruvins$ ls -la
total 0
drwxr-xr-x  4 dhruvins  staff  128 Dec 29 02:52 .
drwxr-xr-x  9 dhruvins  staff  288 Dec 29 17:41 ..
drwxr-xr-x  5 dhruvins  staff  160 Dec 29 02:11 vpc
VW3N7VQKQX:modules dhruvins$

  • Create main.tf file and add below code in it

    # AWS VPC
resource "aws_vpc" "demo_vpc" {
 cidr_block           = var.cidr_block
 instance_tenancy     = var.tenancy
 enable_dns_hostnames = true

 tags = {
   "Name" = "${var.name}-vpc"
 }
}

# Internet Gateway
resource "aws_internet_gateway" "demo_gateway" {
 vpc_id = aws_vpc.demo_vpc.id

 tags = {
   "Name" = "${var.name}-igw"
 }
}

# AZ
data "aws_availability_zones" "az" {}

# AWS Subnet
resource "aws_subnet" "demo_subnet" {
 vpc_id                  = aws_vpc.demo_vpc.id
 cidr_block              = var.cidr_block_subnet
 availability_zone       = data.aws_availability_zones.az.names[0]
 map_public_ip_on_launch = true

 tags = {
   "Name" = "${var.name}-subnet"
 }
}

# AWS Route Table
resource "aws_route_table" "demo_route_table" {
 vpc_id = var.vpc_id

 route {
   cidr_block = "0.0.0.0/0"
   gateway_id = aws_internet_gateway.demo_gateway.id
 }

 tags = {
   "Name" = "${var.name}-route"
 }
}

# Associate public subnet to route table
resource "aws_route_table_association" "demo_association" {
 subnet_id      = aws_subnet.demo_subnet.id
 route_table_id = aws_route_table.demo_route_table.id
}

  • Create variables.tf file and add below code in it

    # CIDR Block for VPC
variable "cidr_block" {}

# Instance Tenancy 
variable "tenancy" {}

# Subnet CIDR
variable "cidr_block_subnet" {}

# Tags
variable "name" {}

  • Create outputs.tf file and add below code in it

    # Getting VPC ID
output "vpc_id" {
  value = aws_vpc.demo_vpc.id 
}

# Getting Subnet ID
output "subnet_id" {
  value = aws_subnet.demo_subnet.id
}

    VW3N7VQKQX:vpc dhruvins$ ls -la
total 24
drwxr-xr-x  5 dhruvins  staff   160 Dec 29 02:11 .
drwxr-xr-x  4 dhruvins  staff   128 Dec 29 02:52 ..
-rw-r--r--  1 dhruvins  staff  1136 Dec 29 19:55 main.tf
-rw-r--r--  1 dhruvins  staff   147 Dec 29 02:49 outputs.tf
-rw-r--r--  1 dhruvins  staff   163 Dec 30 19:23 variables.tf
VW3N7VQKQX:vpc dhruvins$

  • Now out structure for VPC module is ready, we are not using any value for the variables and so that we can different value for different environments later!

Step 2:

  • We need to create the moduel for EC2 instance and so that we can use it for different environment later!

  • Create a folder called ec2 inside modules folder

  • Create main.tf file and add below code in it

    resource "aws_instance" "demo_instance" {

ami               = var.ami_id
instance_type     = var.instance_type
availability_zone = data.aws_availability_zones.az.names[0]
subnet_id         = var.subnet_id

 tags = {
    "Name" = "${var.name}-instance"
  }
}

# AZ
data "aws_availability_zones" "az" {}

  • Create variables.tf file and add below code in it

    # Region
variable "region" {}

# AMI ID
variable "ami_id" {}

# Instance Type
variable "instance_type" {}

# Subnet ID
variable "subnet_id" {}

# Tags 
variable "name" {}

  • Create outputs.tf file and add below code in it

    # Getting Public IP of EC2 instance
output "public_IP" {
  value = aws_instance.demo_instance.public_ip
}

    VW3N7VQKQX:ec2 dhruvins$ ls -la
total 24
drwxr-xr-x  5 dhruvins  staff  160 Dec 11 01:56 .
drwxr-xr-x@ 3 dhruvins  staff   96 Dec 11 21:55 ..
-rw-r--r--  1 dhruvins  staff  223 Dec 11 01:39 main.tf
-rw-r--r--  1 dhruvins  staff   70 Dec 11 01:37 output.tf
-rw-r--r--  1 dhruvins  staff  266 Dec 11 01:38 variables.tf
VW3N7VQKQX:ec2 dhruvins$

  • Now out structure for EC2 module is ready, we are not using any value for the variables and so that we can different value for different environments later

Step 3:

  • Create folders like stg, lve & dev for different environments like below

    VW3N7VQKQX:Terraform_multiple_modules dhruvins$ ls -la
total 16
drwxr-xr-x    9 dhruvins  staff   288 Dec 29 17:41 .
drwx------@ 182 dhruvins  staff  5824 Dec 29 02:15 ..
drwxr-xr-x   14 dhruvins  staff   448 Dec 29 17:42 .git
-rw-r--r--    1 dhruvins  staff   650 Dec 29 17:41 .gitignore
-rw-r--r--    1 dhruvins  staff    28 Dec 29 02:07 README.md
drwxr-xr-x    8 dhruvins  staff   256 Dec 30 19:14 dev
drwxr-xr-x    4 dhruvins  staff   128 Dec 29 02:52 modules
drwxr-xr-x    8 dhruvins  staff   256 Dec 30 19:10 prod
drwxr-xr-x    8 dhruvins  staff   256 Dec 29 19:34 stg
VW3N7VQKQX:Terraform_multiple_modules dhruvins$

  • First, we will define the code for the stg environment

  • Create main.tf file and add below code in it

    module "vpc" {
  source = "../modules/vpc"

  cidr_block        = var.cidr_block
  vpc_id            = module.vpc.vpc_id
  cidr_block_subnet = var.cidr_block_subnet
  name              = var.name
  tenancy           = var.tenancy
}

module "ec2" {

  source = "../modules/ec2"

  ami_id            = var.ami_id
  instance_type     = var.instance_type
  region            = var.region
  subnet_id         = module.vpc.subnet_id
  name              = var.name
}

  • In the above code we are calling the ec2 & vpc module and using the mandatory variables

  • Create provider.tf file and add below code in it

    provider "aws" {
  region = var.region
  profile = "default"
}

terraform {
  backend "s3" {
    bucket = "tf-state-dhsoni"
    region = "us-west-2"
    key    = "stg/terraform.tfstate"
    profile = "default"
  }

  • We are using S3 bucket for storing the state file in it so, that we do not need to maintain it locally and for that I have already created the bucket called tf-state-dhsoni on AWS

  • The above code will create stg folder inside the tf-state-dhsoni bucket and store the state file for stg environment

  • Create variables.tf file and add below code in it

    # CIDR Block for VPC
variable "cidr_block" {}

# Subnet CIDR
variable "cidr_block_subnet" {}

# Instance Tenancy 
variable "tenancy" {}

# Tags
variable "name" {}

# Region
variable "region" {}

# AMI ID
variable "ami_id" {}

# Instance Type
variable "instance_type" {}

  • Create terraform.tfvars file and add below code in it

    cidr_block        = "10.0.0.0/16"
cidr_block_subnet = "10.0.1.0/24"
name              = "stg"
ami_id            = "ami-0a606d8395a538502"
instance_type     = "t2.micro"
region            = "us-east-2"
tenancy           = "default"

  • The above values for all the variables for stg environment

Step 4:

  • Now, we will define the code for the prod environment

  • Create main.tf file and add below code in it

    module "vpc" {
  source = "../modules/vpc"

  cidr_block        = var.cidr_block
  vpc_id            = module.vpc.vpc_id
  cidr_block_subnet = var.cidr_block_subnet
  name              = var.name
  tenancy           = var.tenancy
}

module "ec2" {

  source = "../modules/ec2"

  ami_id            = var.ami_id
  instance_type     = var.instance_type
  region            = var.region
  subnet_id         = module.vpc.subnet_id
  name              = var.name
}

  • In the above code we are calling the ec2 & vpc module and using the mandatory variables

  • Create provider.tf file and add below code in it

    provider "aws" {
  region = var.region
  profile = "default"
}

terraform {
  backend "s3" {
    bucket = "tf-state-dhsoni"
    region = "us-west-2"
    key    = "prod/terraform.tfstate"
    profile = "default"
  }

  • The above code will create prod folder inside the tf-state-dhsoni bucket and store the state file for prod environment

  • Create variables.tf file and add below code in it

    # CIDR Block for VPC
variable "cidr_block" {}

# Subnet CIDR
variable "cidr_block_subnet" {}

# Instance Tenancy 
variable "tenancy" {}

# Tags
variable "name" {}

# Region
variable "region" {}

# AMI ID
variable "ami_id" {}

# Instance Type
variable "instance_type" {}

  • Create terraform.tfvars file and add below code in it

    cidr_block        = "30.0.0.0/16"
cidr_block_subnet = "30.0.1.0/24"
name              = "prod"
ami_id            = "ami-0a606d8395a538502"
instance_type     = "t2.micro"
region            = "us-east-2"
tenancy           = "default"

  • The above values for all the variables for prod environment

Step 5:

  • Now, we will define the code for the dev environment

  • Create main.tf file and add below code in it

    module "vpc" {
  source = "../modules/vpc"

  cidr_block        = var.cidr_block
  vpc_id            = module.vpc.vpc_id
  cidr_block_subnet = var.cidr_block_subnet
  name              = var.name
  tenancy           = var.tenancy
}

module "ec2" {

  source = "../modules/ec2"

  ami_id            = var.ami_id
  instance_type     = var.instance_type
  region            = var.region
  subnet_id         = module.vpc.subnet_id
  name              = var.name
}

  • In the above code we are calling the ec2 & vpc module and using the mandatory variables

  • Create provider.tf file and add below code in it

    provider "aws" {
  region = var.region
  profile = "default"
}

terraform {
  backend "s3" {
    bucket = "tf-state-dhsoni"
    region = "us-west-2"
    key    = "dev/terraform.tfstate"
    profile = "default"
  }

  • The above code will create dev folder inside the tf-state-dhsoni bucket and store the state file for dev environment

  • Create variables.tf file and add below code in it

    # CIDR Block for VPC
variable "cidr_block" {}

# Subnet CIDR
variable "cidr_block_subnet" {}

# Instance Tenancy 
variable "tenancy" {}

# Tags
variable "name" {}

# Region
variable "region" {}

# AMI ID
variable "ami_id" {}

# Instance Type
variable "instance_type" {}

  • Create terraform.tfvars file and add below code in it

    cidr_block        = "20.0.0.0/16"
cidr_block_subnet = "20.0.1.0/24"
name              = "dev"
ami_id            = "ami-0a606d8395a538502"
instance_type     = "t2.micro"
region            = "us-east-2"
tenancy           = "default"

  • The above values for all the variables for dev environment

  • Now, our entire setup is ready for all the different environments!

Run below command one by one from each folder i.e. stg, dev & prod and you will see 3 different instances & for that 3 different VPCs and state file for each environment!

terraform init
terraform plan
terraform apply

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