Develop Terraform Modules Locally

Step-01: Introduction

• How to develop Terraform modules locally ?
• How to leverage and use open source Terraform Modules locally if we don't have access from our organization private networks to Terraform Public Registry ?

Step-02: Copy templates from 06-AWS-VPC

• Copy terraform-manifests from 06-AWS-VPC\06-02-AWS-VPC-using-Terraform\terraform-manifests\v2-vpc-module-standardized

Step-03: Download Public Registry Terraform Module

• Download the VPC module from Terraform Public Registry

Step-04: Create VPC Local Module

• Create modules folder in Terraform Working Directory terraform-manifests
• Copy the downloaded VPC module to modules folder with module folder name aws-vpc
• Remove all other unused or un-required files from this downloaded module.
• Update the source argument in c4-02-vpc-module.tf
• Also comment version argument

# Create VPC Terraform Module
module "vpc" {
  source  = "./modules/aws-vpc"
  #version = "2.78.0"

###  BELOW Terraform code is truncated and will be available in c4-02-vpc-module.tf

Step-05: Execute Terraform Commands

# Terraform Initialize
terraform init
Observation: 
1. Verify the cli output
2. Verify the .terraform\modules folder
3. It will just have the module.json file referencing to local modules folder where aws-vpc module is present

# Terraform Validate
terraform validate

# Terraform Plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

Step-06: Additional Understanding

1. If we want to develop local modules in our organization, don't need to build everything from scratch
2. Analyze what all open source modules available for us and use them and change those as per our requirement.
3. If we don't relevant module, atleast refer these module related code main.tf to get how the advanced level code they write to build such type of re-usable modules

Step-07: Clean-Up

# Terraform Destroy
terraform destroy -auto-approve

# Delete Files
rm -rf .terraform*
rm -rf terraform.tfstate*