Terraform Fundamentals · Module 01 of 12

Infrastructure as code and the Terraform workflow

Understand declarative infrastructure as code, Terraform's desired-state model, and the init → plan → apply → destroy workflow before touching real cloud resources.

Learning objectives

By the end of this module, you should be able to:

Explain declarative infrastructure as code and why it improves repeatability.
Describe what Terraform configuration, providers and state each contribute.
Run the core CLI workflow safely with a provider-free training resource.

Infrastructure as code makes intent reviewable

Infrastructure as code represents desired infrastructure in version-controlled configuration. A change becomes a reviewable diff instead of an undocumented sequence of console clicks.

Terraform is declarative: configuration describes the desired result. Terraform compares configuration, prior state and provider observations to construct a plan.

Terraform has a predictable core workflow

terraform init prepares a working directory, terraform plan previews proposed changes, and terraform apply executes an approved plan. terraform destroy is an explicit teardown operation and deserves the same review discipline as creation.

State is part of the control system

Terraform state maps resource addresses in configuration to managed objects and cached attributes. State is operational data, not source code. Treat it as sensitive and protect concurrent writes.

Worked examples

See the idea in practice.

Provider-free first resource

terraform {
  required_version = ">= 1.6, < 2.0"
}

resource "terraform_data" "hello" {
  input = "gnu-academy"
}

output "message" {
  value = terraform_data.hello.output
}

terraform_data is built in and requires no external provider.
It is ideal for learning lifecycle behavior without creating cloud infrastructure.

Hands-on lab

Lab — Execute the safe Terraform lifecycle

Goal: Initialize, format, validate, plan and apply a provider-free configuration.

Before you start

Terraform CLI 1.6+; the course validator is aligned to Terraform 1.16.x.
No cloud account or provider credentials are required.

STEP 1

Create the configuration

mkdir -p ~/gnu-terraform-labs/module01 && cd ~/gnu-terraform-labs/module01
cat > main.tf <<'EOF'
terraform {
  required_version = ">= 1.6, < 2.0"
}

resource "terraform_data" "hello" {
  input = "gnu-academy"
}

output "message" {
  value = terraform_data.hello.output
}
EOF

STEP 2

Initialize and validate

terraform init
terraform fmt
terraform fmt -check
terraform validate

STEP 3

Review the plan

terraform plan

STEP 4

Apply and inspect output

terraform apply -auto-approve
terraform output message

Verify

terraform validate reports success.
The plan shows one terraform_data resource to add.
The output resolves to gnu-academy.

Expected outcome

You can explain what init, plan and apply do before using a cloud provider.

If it fails

If terraform is not found, install the CLI and verify terraform version.
If fmt -check fails, run terraform fmt and retry.

Real-world connection

Production workflows usually save or remotely execute plans, require review for privileged changes, and keep state in a protected backend.

Avoid these traps

Common mistakes

Running apply before reading the plan.
Treating state as an ordinary text file to edit by hand.
Assuming Terraform itself is a cloud provider.

Knowledge check

Can you explain it without looking back?

Open each answer only after you have tried to answer the question yourself.

1What does terraform plan do?

It calculates and displays proposed changes without applying them.

2Why is configuration called declarative?

It describes the desired end state rather than scripting every imperative step.

3Why protect state?

It maps managed objects and can contain sensitive infrastructure data.

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