Terraform Initial Setup

Navigate to the terraform-backend directory in this repo
This directory is responsible for creating backend resources for the terraform env i.e s3 bucket, dynamodb table etc.
Make sure you configure credentials file in the home directory such that credentials are named as workspace names i.e dev, prod etc
Follow below mentioned terraform execution steps as they will be same for backend resources creation as well as creating other terraform resources

Terraform Execution Steps

Create a terraform workspace.

Ex. dev, prod.

  terraform workspace create <WORKSPACE_NAME>

Initialize terraform

This will download all the plugins and modules required for execution of terraform code.
```
  terraform init -backend-config="<WORKSPACE_NAME>.s3.tfbackend"
```
Note : For creating backend resources we don't need to pass backend-config as the state file for backend resources will be stored in repo it self
```
  terraform init
```

Terraform plan

This will give us the idea what resources will be created or updated by terraform.
Variables will differ for each workspace, so please pass the variables file while executing plan command.
```
  terraform plan -var-file='<WORKSPACE_NAME>.tfvars'
```

Terraform apply

This will create or update the resources shown in previous step.
Variables will differ for each workspace, so please pass the variables file while executing plan command.
```
  terraform apply -var-file='<WORKSPACE_NAME>.tfvars'
```

Repo Structure

terraform-infrastructure

It contains code to create necessary infrastructure required for the applications.
It will creat necessary netoworking components, database, compute resources as well as container infrastructure required for the applications.
It utilizes various modules present in terraform-modules directory.
To add new resources in the infrastructure modules from terraform-modules can be reused and required configuration can be specified.
To add new resources other than those present in terraform-modules , new module should be created such that it can be reused whenever needed in future.

To create infra follow the steps given in terraform execution section or refer the below commands.

  terraform init -backend-config="<WORKSPACE_NAME>.s3.tfbackend"
  terraform plan -var-file='<WORKSPACE_NAME>.tfvars'
  terraform apply -var-file='<WORKSPACE_NAME>.tfvars'

terrraform-modules

This directory contains various modules which are required in our infrastructure.
This modules are written in such a way that they can be reused to create resources with required infrastructure.
This module needs to be referenced in appropriate directory with required values for the variables.

Below is the description of modules present in the terraform-modules directory

network:

  This module is responsible for creating VPC, subnets, internet gateways, NAT etc in the infrastructure.

database:

  This module is resposible for creating rds db with secrets rotation in the infrastructure. This module internally uses secret-manager-with-rotation module

compute:

   This module is responsible for creating certificates for the domains using AWS ACM service and also configuring application load balancer for serving requests. This module internally uses acm-multiple-domains module.

container:

   This module is responsible for creating all the necessary ecr repos, ecs clusterr required by the application services to run successfully.

app-services:

  This is the module responsible for creating tasks and services in the ecs cluster depending on the configuration passed to it. This module is used by terraform-applications directory.

terraform-applications

This directory is resposible for deploying our services to the ecs cluster.

For deploying service to the ecs cluster , navigate to the respective service directory and follow the terraform execution section or refer the below commands

  terraform init -backend-config="<WORKSPACE_NAME>.s3.tfbackend"
  terraform plan -var-file='<WORKSPACE_NAME>.tfvars'
  terraform apply -var-file='<WORKSPACE_NAME>.tfvars'

If any service needs to be added in future , a directory with service name should be added to this directory using previously created service as a reference.
Depending on the backend config using during initialization and vars file used during apply , service will be deployed to respective environment/account.

SumitPokale7/dev_infra_Terraform