# Preparing a backup image for cloud-init (reuse as golden image)

This describes what was done to the **device** (e.g. 10.20.50.147) so the **backup image** you take from it is smaller and suitable for deployment as a **golden image** with cloud-init running on first boot.

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## 1. Size reductions applied

| Action | Effect |
|--------|--------|
| Removed old kernel (6.12.47) and headers | ~130 MB freed; current kernel 6.12.62 kept |
| APT cache already cleaned | (done earlier) |
| Logs truncated, journal vacuumed | (done earlier) |
| KDE/Plasma removed | (done earlier; ~2.6 GB freed) |

**Result:** Root filesystem ~**7.5 GB** used (28% of 29 GB). After taking the backup you can shrink with **PiShrink** (and optionally compress) for storage and faster deploy; see [EMMC-PROVISIONING-GUIDE.md](EMMC-PROVISIONING-GUIDE.md#shrinking-backup-and-golden-images-pishrink).

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## 2. Cloud-init preparation (so it re-runs after deploy)

These steps were run on the device so that when you **restore this image** to another reTerminal (or the same one after wipe), the next boot is treated as **first boot** and cloud-init runs again.

| Step | What was done |
|------|----------------|
| **cloud-init clean** | `cloud-init clean --logs --machine-id --seed` so cloud-init state and seed are removed; next boot is detected as first boot. |
| **machine-id** | Set to `uninitialized`; systemd will generate a new unique ID on first boot. |
| **SSH host keys** | Removed from `/etc/ssh/`; `regenerate_ssh_host_keys.service` (or cloud-init) will create new keys on first boot. |
| **Hostname** | Reset to `raspberrypi` in `/etc/hostname` and `/etc/hosts`; cloud-init can set the real hostname from **meta-data** or **user-data**. |

No reboot was performed on the device so you can take the backup immediately.

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## 3. Boot partition (NoCloud)

The device already had cloud-init **NoCloud** files on the boot partition:

- `/boot/firmware/user-data`
- `/boot/firmware/meta-data`
- `/boot/firmware/network-config`

When you use this backup as **golden image** and deploy it:

1. **Cloud-init** will run on first boot and use these files.
2. If **user-data** is set up to download and run your **first-boot script** (e.g. from the provisioning portal), ensure:
   - The **FILE_SERVER** URL in that script (or in `first-boot.conf` on the server) is correct for the deployed network (e.g. `http://10.20.50.1:5000/files/first-boot` or your LXC IP).
   - The portal has the right **first-boot.conf** and **first-boot** assets (sync with `scripts/sync-portal-files-to-lxc.sh`).

If you prefer different **user-data** / **meta-data** / **network-config** (e.g. different hostname, WiFi, or runcmd), either:

- Edit them **on the device** before taking the backup, or  
- After copying the image to the host, **mount the boot partition** of the image and replace `user-data`, `meta-data`, and optionally `network-config` with your versions (see [EMMC-PROVISIONING-GUIDE.md](EMMC-PROVISIONING-GUIDE.md)).

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## 4. Optional: further size reduction

If you need a smaller image:

- **Remove unused locales** (e.g. with `localepurge` or by removing locale packages); can save hundreds of MB.
- **Remove more packages** (see [DEVICE-REMOVABLE-PACKAGES.md](DEVICE-REMOVABLE-PACKAGES.md)): e.g. CUPS, NFS, development tools, extra fonts.
- **PiShrink** the backup after imaging (shrinks rootfs and optionally compresses); see the guide above.

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## 5. Taking the backup

1. Use your normal **Backup** flow (e.g. reTerminal in boot mode → dashboard **Backup**), or `dd`/clone the eMMC to a file.
2. Optionally run **PiShrink** (and compress) on the host.
3. Set the result as **golden image** in the dashboard if you want to deploy it to other devices.
4. On first boot after deploy, cloud-init will run; SSH host keys and machine-id will be new; set hostname and the rest via **user-data** / **meta-data** or your first-boot script.