Terraform: principles, architecture and workflow

1. Declarative infrastructure as code #

Describing the desired state.

Principle #

With Terraform, you describe the desired state of the infrastructure in HCL files; Terraform computes the actions needed to get there (create, modify, delete) and runs them in the right order thanks to a dependency graph.

2. The workflow #

init, plan, apply, destroy.

Commands #

terraform init          # télécharge les fournisseurs, configure le backend
terraform fmt -recursive && terraform validate
terraform plan -out=plan.tfplan
terraform apply plan.tfplan
terraform output
terraform destroy       # supprime tout ce que gère cette configuration

Reading a plan #

3. The ecosystem #

Terraform, OpenTofu, HCP Terraform.

Overview #

Good practice: Pin the version of Terraform and the providers (required_version, required_providers) for reproducible runs.