@02/02/2023

IAAC defined

• provisioning infra through software for consistent and predictable deployments

• useful when running multiple environments

Core Concepts

• IAAC is defined in code, creating files like JSON or YAML or Hashicorp Config language

• IAAC is stored in source control, like Git or GitHub.
  • can be worked on by multiple developers simultaneously

• IAAC can be declarative or imperative

• Idempotency and Consistency

• Pushing or Pulling configurations to environment

Declarative or Imperative

Imperative software tells the proper order of deployment, procedural, exacty

Declarative Software has a rough idea how to make environment, using a config language you can declare what type of thing (food), with a sub-type (taco), and within the config-block can list the components (ingredients).

The software already has a predefined routine how to get ingredients, and and a predefined order to deploy them.

The defaults can be changed by adding options to config block.

Terraform using Declarative software

Idempotent and Consistent

• In idempotent software, the software is aware of the state of the world and will not redeploy infrastructure that it already knows exists.
  • i.e. if you haven’t changed anything about code and apply to same environment, the software will not act because the instruction already matches the environment’s infra.

• In non idempotent software, every time instruction is given, something is deployed

• Terraform attempts to be idempotent

Push or Pull

• Terraform is a push type model.

• The config in Terraform gets pushed to the env

• Pull type model is when there’s an agent running in target env and pulls its config from a central source

Benefits of IAAC

1. Automated Deployment,
   1. faster usually better

2. Repeatable
   1. each time you need to build out or update env

3. Creates multiple consistent environment.
   1. Useful for ensuring Dev, QA, Staging and Production envs to match

4. Reusable components
   1. as process is defined in code, it can be reuse in any application that needs a similar back-end, makes life a lot easier
   2. Follows the DRY programming principle, Don’t Repeat Yourself

5. Documented Architecture
   1. natural result of defining in code, gives a better understanding of architecture and how it works

Overview of Terraform

• IAAC isn't scary

• Manual processes are the enemy, mistakes happen

• Automating makes sense

• If caught in a roadblock, step away from problem, helps with thinking process