feat(backup): 3-2-1 backup strategy with multi-target support

[Heykool]

Summary

Implements the 3-2-1 backup strategy for the homelab-stack as described in issue #12.

What was implemented

scripts/backup.sh — Full-featured backup script with:

• — backup all stacks or media-only
• — preview what would be backed up
• — restore from any backup
• — list available backups
• — verify backup integrity
• Multi-target support:
• Docker volumes + configs + databases backup
• ntfy push notifications on success/failure
• Backup manifest with metadata
• Retention policy ()
• Existing was completely rewritten; still works standalone

docs/disaster-recovery.md — Complete DR guide with:

• Full restore procedure (fresh host from scratch)
• Service restore order: Base → Databases → SSO → Monitoring → Storage → Network → Applications
• RTO estimates (full restore: 2–4h, volume only: 30–60min, single service: 5–15min)
• Verification checklist (base infra, DBs, SSO, monitoring, storage, media, notifications)
• Configuration guide for all backup targets (S3/MinIO, Backblaze B2, SFTP, Cloudflare R2)
• systemd timer + crontab setup instructions

systemd/ — Daily 2:00 AM automation:

• — runs at 02:00 with 15min jitter
• — runs the backup script

.env.example — Added backup configuration section:

• , ,
• ,
• AWS/B2/SFTP credential variables

Acceptance Criteria

• backup.sh --target all backs up all volumes, configs, and databases
• backup.sh --target media backs up media volumes only
• --dry-run previews without writing
• --restore <id> performs full restore
• --list shows available backups
• --verify validates backup integrity
• Local, S3, B2, SFTP, R2 targets supported via .env
• Daily 2:00 AM timer/systemd schedule
• ntfy notifications on backup success/failure
• DR docs with restore procedure, service order, RTO, verification checklist
• New files documented in README updates

Testing

# Dry run
./scripts/backup.sh --target all --dry-run

# List backups
./scripts/backup.sh --list

# Enable daily timer
sudo cp systemd/*.service /etc/systemd/system/
sudo systemctl enable --now homelab-backup.timer

Bounty

• Issue: [BOUNTY $150] Backup & DR — 自动备份 + 灾难恢复 #12
• Bounty: $150 USDT
• Payment: PayPal he.zouiten@hotmail.fr | ETH 0xC64B172b40721D36318CC4D93111d352d019C40A