Tohuwabohu excorcism

Installation https://askubuntu.com/questions/983351/how-to-install-terraform-in-ubuntu

Introduction: https://www.terraform.io/intro/getting-started/build.html

Skeleton project https://github.com/skipidar/terraform-skeleton

#!/bin/bash
set -eo pipefail

if [[ ! -d ".terraform" ]]
then
  terraform init
fi

terraform validate
terraform plan

#terraform apply

https://developer.hashicorp.com/terraform/tutorials/configuration-language/provider-versioning

terraform init -upgrade

Initializing the backend...

Initializing provider plugins...
- Finding hashicorp/aws versions matching "~> 5.0"...
- Installing hashicorp/aws v5.21.0...
- Installed hashicorp/aws v5.21.0 (signed by HashiCorp)

Terraform has made some changes to the provider dependency selections recorded
in the .terraform.lock.hcl file. Review those changes and commit them to your
version control system if they represent changes you intended to make.

Terraform has been successfully initialized!

Create “main.tf”

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"
    }
  }
}

provider "aws" {
  profile = "default"
  region  = format("%s", var.aws_region)
}

Create “variables.tf”

variable "aws_region" {
  description = "The AWS region to deploy the resources into"
  type = string
  default = "eu-central-1"
}

variable "aws_account_id" {
  description = "The AWS account identifier of the project"
  type = string
  default = "1234567891234"
}

variable "prefix" {
  description = "The resource prefix"
  type = string
  default = "alf-dev-con1"
}


locals {
  iot_policy = "${var.prefix}-thing2"
}

locals defines inner variables. Only here one can combine other variables

Use the variable

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

Create templates.tf

data "template_file" "tf_iot_policy" {
  vars = {
    aws_region = "${var.aws_region}"
    aws_account_id = "${var.aws_account_id}"
  }
  template = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "iot:Connect",
        "iot:Publish",
        "iot:Receive",
        "iot:Subscribe"
      ],
      "Resource": "arn:aws:iot:$${aws_region}:$${aws_account_id}:*"
    }
  ]
}
EOF
}

Usage

resource "aws_iot_policy" "iot_policy" {
  name   = "${local.iot_policy}"
  policy = "${data.template_file.tf_iot_policy.rendered}"
}