Terraform

Infrastructure as code. Orchestration tool for building, changing, versioning infrastructure.

• works declaratively (similar to Ansible in that you don't necessarily tell it how to get to the specified state)
• differs from Ansible in that it has a focus on the orchestration part of instances compared to configuration
• infrastructure as code is a main goal, much like many of these dev-ops tools
• execution plan, generates steps of how to get to desired state
• resource graph is a DAG of dependencies, allows parallelization (looks like spark)
• user data is a configuration that allows shell execution after hardware is provisioned
  • useful for configurations that need to be dynamic
• terraform provisions resources, defined in .tf files, from possibly multiple providers like digital ocean and aws

Provisioner

Used to execute scripts on a local or remote machines, a part of resource creation or destruction

• a failed provisioner caused a tainted resource status
  • terraform cannot reason about what exact state a resource failed in, so it will destroy and recreate upon terraform apply

State

Terraform uses state to map real world resources to your intended configurations

• uses state to track metadata like dependencies