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Core Concepts

MAAS (Metal as a Service)​

✔ Bare-metal provisioning tool by Canonical
✔ Automates OS installation via PXE
✔ Manages DHCP, DNS, IP assignment
✔ Injects SSH keys automatically

MAAS treats physical machines the same way cloud platforms treat virtual machines — you enlist, commission, and deploy them through a UI or API.

PXE Boot​

✔ Network boot instead of disk boot
✔ Used for automated OS deployment
✔ Triggered via BIOS (F12 → Network Boot)

When a node boots via PXE:

  1. It receives an IP from MAAS DHCP
  2. Downloads a boot image over the network
  3. MAAS installs the OS automatically
  4. Machine is ready for SSH access

Cloud-init​

✔ Industry-standard post-install configuration system
✔ Used for:
  - hostname assignment
  - package installation
  - system configuration (sysctl, timezone)

:::warning Important lesson Do NOT define users in cloud-init when using MAAS. MAAS handles SSH key injection automatically. Overriding this causes SSH access failures. :::

Key Principle​

Provisioning → MAAS
Configuration → Cloud-init

Keep these responsibilities separated. MAAS handles getting the OS on the machine, cloud-init handles configuring it.