# Terraform Patterns

> Terraform IaC Patterns

- Skill: `j4flmao/terraform-patterns` (Agent Skill)
- Install (CLI): `npx skillmds@latest add j4flmao/terraform-patterns`
- Raw SKILL.md: https://api.skillmd.com/api/skills/j4flmao/terraform-patterns/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: j4flmao (https://skillmd.com/u/j4flmao)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/j4flmao/terraform-patterns

---

# Terraform IaC Patterns

## Core Concepts

Terraform is a declarative tool for provisioning infrastructure. Instead of writing scripts to create servers, you define the desired state, and Terraform executes the API calls to make reality match the state.

### 1. State Management (`.tfstate`)
Terraform maps real-world resources to your configuration using a state file. For teams, state MUST be stored remotely (e.g., AWS S3, Terraform Cloud) to avoid conflicts and loss.
- **State Locking:** Use DynamoDB tables alongside S3 to "lock" the state file, preventing two developers from running `terraform apply` simultaneously and corrupting infrastructure.

### 2. Modules (DRY Principle)
Encapsulate complex resource combinations (VPC + Subnets + NatGateway) into reusable modules. Consume modules using variables.

### Terraform Lifecycle Map

```mermaid
%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
    subgraph Local ["Developer Workspace"]
        A["Write HCL Code (.tf)"]
        B["terraform init"]
        C["terraform plan"]
        D["terraform apply"]
    end
    
    subgraph Backend ["Remote State Backend"]
        E["State File (.tfstate in S3)"]
        F["State Lock (DynamoDB)"]
    end
    
    subgraph Cloud ["Cloud Provider (AWS/GCP)"]
        G["Cloud API (Create/Update/Delete)"]
        H["Provisioned Resources"]
    end
    
    B -.->|"Downloads Providers"| A
    C -->|"Reads State"| E
    C -->|"Acquires Lock"| F
    D -->|"Executes"| G
    G -->|"Manages"| H
    D -->|"Writes Updated State"| E
```