# Terraform > Terraform and OpenTofu best practices for variables, modules, descriptions, resources, plan, and import Use when this capability is needed. - Skill: `tomevault-io/terraform-4` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/terraform-4` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/terraform-4/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: DevOps & Infra - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/terraform-4 --- # Terraform ## Plan and import - Don't run `terraform plan` directly; instead give the command and ask the user to execute it. - NEVER run terraform import manually; use import statements instead. ## Variables - Do not set `nullable = true` on variables; that is the default and is redundant. - Only set `nullable = false` when the variable must not be null. - Pass every value explicitly at the call site. Defaults and fallbacks—variable defaults, provider defaults, resource defaults, coalesce/fallback patterns—hide decisions and make behavior opaque. We hate them; use only as a last resort. ## Module structure - Single call per concern: one module call per cohesive concern; merge related pieces into one module. ## Variables and outputs - Remove unused outputs; keep only outputs that are referenced. - Minimize environment config; don't parametrize values that never vary across environments. ## Descriptions - Omit `description` unless it adds information not visible from the code; remove if unused. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/vnord) — claim your Tome and manage your conversions.