# Runbook: Platform VM / Lab Host VM Rebuild

Both VMs are designed to be disposable and rebuildable from code — nothing irreplaceable
should ever live only on either VM's disk outside of what's backed up (`docs/BACKUP_DR.md`).

## rn-platform-01 lost

Academic data survives (it's in Postgres backups, off-host). Instructor/student accounts and
progress are recoverable; anything since the last backup is not (`docs/BACKUP_DR.md`'s RPO).

```bash
cd infra/terraform && terraform apply   # recreates the VM from the template
cd ../ansible && ansible-playbook site.yml -i inventory/production.ini --limit platform --ask-vault-pass
# Then restore Postgres — docs/RUNBOOK_POSTGRES_RESTORE.md, step 5b variant (fresh DB this time,
# no need to rename since it's a fresh instance)
./infra/scripts/production-smoke-test.sh
```

## rn-lab-host-01 lost

**No academic data is lost** — this host only ever holds disposable Lab containers by design
(`docs/BACKUP_DR.md`'s Tier distinction). Every enrolled student's Lab needs re-provisioning
after this, which is a normal "Prepare Labs" click, not a recovery operation.

```bash
cd infra/terraform && terraform apply
cd ../ansible && ansible-playbook site.yml -i inventory/production.ini --limit lab_host --ask-vault-pass
# Re-generate Docker TLS material for the new host if its identity (IP/DNS) changed —
# docs/RUNBOOK_DOCKER_TLS_ROTATION.md
# From /admin: Prepare Labs again for any cohort that needs it.
```