Terraform

code for article pfeilbr/terraform-playground

learn and experiment with Terraform

Notes

Execution Plans - describing what it will do and asks for your approval before making any infrastructure changes. This allows you to review changes before Terraform creates, updates, or destroys infrastructure.
Resource Graph - Terraform builds a resource graph and creates or modifies non-dependent resources in parallel.

Module Demo

see mymodule01

cd mymodule01/examples/app01
terraform init
terraform plan
terraform apply -auto-approve

Resources

represent infrastructure objects
each resource type is implemented by a provider, which is a plugin for Terraform that offers a collection of resource types
Meta-Arguments
- depends_on
- count - creates that many instances of the resource or module
- for_each - value is a map or a set of strings, Terraform will create one instance for each member of that map or set
- provider - use to override tf default provider. e.g. you want to change the region for a given resource
- lifecycle
- provisioner and connection

Syntax

resource TYPE NAME {
    BODY
}

Data Sources

Terraform Language

use hcl or json to declare
Blocks - containers for other content and usually represent the configuration of some kind of object
Arguments - assign a value to a name
Expressions - represent a value, either literally or by referencing and combining other values

State

by default state is stored locally in *.tfstate file (the default backend)

when multiple people or clients are collaborating on infra via tf, state can be stored in a remote backend

e.g. state for aws can be stored in S3 and a dynamodb table is used for locking when the state is shared amongst many people and/or systems

terraform {
  backend "s3" {
    # Replace this with your bucket name!
    bucket         = "terraform-up-and-running-state"
    key            = "global/s3/terraform.tfstate"
    region         = "us-east-2"

    # Replace this with your DynamoDB table name!
    dynamodb_table = "terraform-up-and-running-locks"
    encrypt        = true
  }
}

Workspaces - allow you to store your Terraform state in multiple, separate, named workspaces

CLI

# plan
terraform plan

# apply
terraform apply -auto-approve

# validate
terraform validate

# show outputs
terraform output