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Architecture Overview

Every example in this collection follows the same layered architecture pattern.

Resource hierarchy​

Shared network module​

The modules/network module is used by every example. It creates:

  • One VPC and one Basic subnet
  • A security group for the VM with configurable ingress rules
  • An Elastic IP for the VM
  • Optionally: a separate security group + Elastic IP for DBaaS

App-specific security rules (e.g. MySQL port 3306 restricted to the VM IP) are created in the example module, not in the shared module. This keeps the module generic.

cloud-init bootstrap pattern​

All examples use templatefile() to render a cloud-init.yaml.tpl file:

user_data = templatefile("${path.module}/cloud-init.yaml.tpl", {
  db_host    = module.network.dbaas_elastic_ip_address
  db_name    = arubacloud_database.this.name
  # ...
})

The template uses write_files to write configuration files and runcmd to install and start services. This is entirely idempotent and requires no SSH access after deployment.

Naming convention​

All resource names follow {app}-{environment}-{type}, for example:

  • wp-prod-vpc
  • wp-prod-vm-sg
  • wp-prod-vm-eip

This is controlled by the app_name and environment variables in each example.