version: 1
id: terraform-modules
title: Split a Terraform Network Module
summary: Extract a reusable network module with a variable and output, then call it from the root module.
difficulty: intermediate
estimatedMinutes: 35
prerequisites: [terraform-basics]
image: alpine:3.21
shell: /bin/sh
setup:
  - "mkdir -p /workspace/infra/modules/network"
  - "printf 'Ticket: Move VPC CIDR into modules/network and call it from the root.\\nRoot should pass vpc_cidr = \"10.0.0.0/16\".\\n' > /workspace/infra/TICKET.md"
  - "printf 'terraform {\\n  required_version = \">= 1.5.0\"\\n}\\n\\nlocals {\\n  app_name = \"payments\"\\n}\\n\\noutput \"app_name\" {\\n  value = local.app_name\\n}\\n' > /workspace/infra/main.tf"
tasks:
  - id: network-module
    title: Create and call the network module
    description: 'Write /workspace/infra/modules/network/variables.tf with variable vpc_cidr, modules/network/outputs.tf outputting vpc_cidr, and modules/network/main.tf that uses var.vpc_cidr (for example in a local). Update /workspace/infra/main.tf with a module "network" block source = "./modules/network" and vpc_cidr = "10.0.0.0/16". Write /workspace/infra/STATUS.txt containing MODULE_OK.'
    hints:
      - 'Tip code MISSING_MODULE_SOURCE: root module blocks need source = "./modules/network".'
      - 'Variable and output names should both be vpc_cidr.'
      - 'STATUS.txt should include MODULE_OK.'
    checks:
      - type: file
        name: Variable file present
        path: /workspace/infra/modules/network/variables.tf
        value: vpc_cidr
      - type: file
        name: Output file present
        path: /workspace/infra/modules/network/outputs.tf
        value: vpc_cidr
      - type: file
        name: Module body present
        path: /workspace/infra/modules/network/main.tf
        value: var.vpc_cidr
      - type: command
        name: Root calls network module
        command: "grep -Eq 'module[[:space:]]+\"network\"|module[[:space:]]+network' /workspace/infra/main.tf"
      - type: file
        name: Module source set
        path: /workspace/infra/main.tf
        value: "./modules/network"
      - type: file
        name: CIDR passed to module
        path: /workspace/infra/main.tf
        value: "10.0.0.0/16"
      - type: file
        name: Module status ok
        path: /workspace/infra/STATUS.txt
        value: MODULE_OK
limits: {cpus: "0.5", memory: 128m, pids: 64, timeout: 1800, network: false}