# expand-root-lv role

Idempotent role that extends the root LVM logical volume to fill its
volume group and grows the underlying filesystem (ext4 or xfs).

## Where this runs in the lifecycle

Part of the **day0** host-provisioning lifecycle. The canonical entry
points are:

```
playbooks/day0_expand_root_lv.yml   # standalone
playbooks/day0_provision.yml        # umbrella (baseline + expand_root_lv)
```

Day1 application-deploy playbooks should NOT include this role —
day0 is assumed complete before day1 begins.

## Why this role exists

The Ubuntu Server autoinstall template (used by the mk-labs `wed`-baked
VM templates) provisions the root LV at roughly half the available disk
size — a longstanding installer default that surprises every operator
who hasn't been bitten by it before. ~90% of mk-labs VMs need this
fix-up before they're fully useful.

## Idempotency

- If `vg_free_count == 0`, the `lvextend` step is skipped and the
  filesystem-grow step is also skipped (nothing to resize against).
- If the target volume group doesn't exist on the host (e.g. a non-LVM
  layout), the role exits cleanly via `meta: end_play`.
- Safe to leave in a recurring playbook so future disk expansions
  (Proxmox-side disk grow → reboot → run role) are picked up
  automatically.

## Opt-out for multi-LV hosts

If a host will have a **second logical volume in the same VG** (e.g. a
dedicated `/var/lib/postgresql` LV for a database server), this role's
"grow root to fill VG" behavior is wrong — it will consume the free PE
that was being reserved for the second LV.

Set in `host_vars/<host>.yml`:

```yaml
expand_root_lv_skip: true
```

The day0 playbook checks this flag and skips the role cleanly.

## Defaults

| Variable                      | Default       | Purpose                                             |
|-------------------------------|---------------|-----------------------------------------------------|
| `expand_root_lv_vg_name`      | `ubuntu-vg`   | LVM volume group name (Ubuntu installer default).   |
| `expand_root_lv_lv_name`      | `ubuntu-lv`   | LVM logical volume name (Ubuntu installer default). |
| `expand_root_lv_mountpoint`   | `/`           | Mountpoint of the filesystem to grow.               |

Override the VG/LV names in `host_vars/<host>.yml` for hosts that use a
different LVM layout.

## Limitations

- Does not extend the underlying partition. If the operator grows the
  Proxmox disk and the partition itself needs to grow before lvextend
  can claim the new space, run `growpart /dev/sda 3` (or equivalent)
  first. A future enhancement could automate this via `cloud-utils`'
  `growpart` package, but it's out of scope for the initial template
  fix-up case where the partition already covers the whole disk.