terraform-module

A reusable Terraform module separates concerns into main.tf for resources, variables.tf for typed inputs with validation blocks, outputs.tf for exported resource IDs, and versions.tf for provider constraints. Include examples/ and nested modules/ directories for composition.

Configure an S3 backend block in backend.tf pointing to a versioned, encrypted bucket, and add a DynamoDB table with a LockID hash key for state locking. This prevents concurrent edits when multiple team members run terraform apply.

Use for_each with a set or map when resources may be added or removed, since it keys resources by name and avoids destructive reordering. Use count only for simple positional lists where index stability is guaranteed.

Create separate directories per environment, each with its own terraform.tfvars file and isolated state key in the S3 backend. This isolates the blast radius so a dev change cannot affect production state.

Yes, Terratest is a Go library that runs terraform init, apply, and destroy against example configurations and asserts on outputs. In CI, run terraform fmt, validate, and plan on pull requests before any apply.

A state lock error occurs when another apply is running or a previous run crashed without releasing the DynamoDB lock. Verify no active runs exist, then use terraform force-unlock with the lock ID to clear it.