Terraform Infrastructure As Code Study Notes

Common Terraform Pitfalls

A field guide to the mistakes Terraform users make most often — from state file mishandling to accidental destroys — and how to avoid each one.

count and for_each

Compare Terraform's two meta-arguments for creating multiple copies of a resource or module, and understand why for_each is usually the safer choice.

Data Sources Explained

Learn how Terraform data sources let you read information about existing infrastructure or external systems without managing it, so configurations can referenc…

Declarative vs Imperative IaC

Declarative IaC describes the desired end state and lets the tool compute the steps, while imperative IaC specifies the exact sequence of actions to perform; e…

Drift Detection

Understand configuration drift — when real infrastructure diverges from Terraform state — and the tools and practices used to detect and reconcile it before it…

Dynamic Blocks

Learn how to generate repeated nested configuration blocks programmatically inside a resource, avoiding hand-written repetition for variable-length nested sett…

Expressions and Functions

HCL expressions let you reference values, perform operations, and transform data using Terraform's extensive built-in function library. This topic covers refer…

File and Directory Structure Conventions

Consistent file layout and naming conventions keep Terraform projects navigable as they grow, separating variables, outputs, providers, and resources predictab…

HCL Syntax Fundamentals

HashiCorp Configuration Language (HCL) is the declarative syntax underlying every Terraform file. Mastering its blocks, arguments, and expressions is the found…

Implicit vs Explicit Dependencies

Learn how Terraform automatically infers resource ordering from configuration references, and when you must override that inference with depends_on.

Importing Existing Infrastructure

Importing lets Terraform take ownership of resources that already exist in a cloud account, bringing them under state management without recreating them.

Installing and Configuring Terraform

Covers installing the Terraform CLI across platforms, verifying the install, managing versions, and configuring credentials and CLI settings for provider authe…

Outputs and Locals

Output values expose data from a module for use by callers or the CLI, while local values let you name and reuse computed expressions within a module. Together…

Plan Review and Policy as Code

Explore how teams review `terraform plan` output for correctness and safety, and how policy-as-code tools like Sentinel and OPA automatically enforce organizat…

Providers Explained

Providers are Terraform plugins that translate HCL resource definitions into API calls against a specific platform, such as AWS, Azure, GCP, or Kubernetes.

Provisioners and When to Avoid Them

Understand Terraform's provisioner blocks for running scripts on resource creation, why HashiCorp considers them a last resort, and what to use instead.

Provisioning AWS Resources

A practical walkthrough of configuring the AWS provider and provisioning core compute, networking, and storage resources with Terraform.

Provisioning Azure and GCP Resources

Understand how the azurerm and google providers differ from AWS in structure and authentication, with practical examples of provisioning core resources on each…

Refactoring State with moved Blocks

The moved block lets Terraform track renamed or relocated resources declaratively, avoiding destructive replace plans when refactoring configuration.

Remote State Backends

Remote backends store Terraform's state file outside the local disk, enabling team collaboration, durability, and integration with locking mechanisms.

Resources and Resource Blocks

The resource block is Terraform's fundamental unit of infrastructure declaration, describing a single managed object like a virtual machine, network, or storag…

Secrets Management in Terraform

Learn how to keep API keys, passwords, and certificates out of your Terraform code and state, using dedicated secret stores and encryption strategies.

State Locking

State locking prevents two Terraform operations from writing to the same state file simultaneously, protecting against corruption and lost updates.

Terraform Cloud and Terraform Enterprise

Understand HashiCorp's managed and self-hosted platforms for running Terraform collaboratively, including remote runs, workspaces, and policy enforcement.