Notes

Looking to consolidate some tested TF useful/basic examples along with some tips gained thru learning experience :)

Versions

% terraform version
Terraform v0.13.5

OSX 10.15.7

Terraform 0.12 and 0.13 changes

Providers (0.13+)

(from https://www.terraform.io/upgrade-guides/0-13.html)

Prior to 0.13: automatic provider installation only for providers packaged and distributed by HashiCorp. Providers built by the community required manual installation by extracting their distribution packages into specific local filesystem locations.

Terraform 0.13+ : new hierarchical namespace for providers to separate HashiCorp and community providers

Terraform now requires explicit source information for any providers that are not HashiCorp-maintained, using a new syntax in the required_providers nested block inside the terraform configuration block

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
      version = "3.12.0"
    }
  }
}

hashicorp is the namespace for Hashicorp-maintained provider plugins (note: HC namespace declaration is not mandatory while others are but cleaner syntax - source = provider/name)

Variables (0.12+)

Variable syntax pre-terraform 0.12 (?)

(aka Interpolation syntax: https://www.terraform.io/docs/configuration-0-11/interpolation.html)

provider "aws" {
    access_key = "${var.access_key}"
    ...
}

Variable syntax with terraform 0.13

provider "aws" {
  access_key = var.aws_access_key
  ...
} 

Managing values for module vars (0.12+)

(Ref: https://www.terraform.io/docs/configuration/variables.html)

Terraform Cloud

TBD

thru cli using -var

terraform apply -var="image_id=ami-abc123"

variable definition files (.tfvars)

terraform apply -var-file="testing.tfvars"

variable files automatically loaded by TF (by order of priority):

• files with names ending in .auto.tfvars or .auto.tfvars.json. (processed in lexical order)
• terraform.tfvars.json
• terraform.tfvars

use TF Environment variables

TF_VAR_ + name of the declared variable

export TF_VAR_aws_access_key="xxxxxxxxxxxx"

CLI input

default values

use default key in variable declaration