# ISO Overhaul: Custom Minimal Base + Branding + Size Optimization

## Context

The Archipelago ISO is ~3.9GB — too large. The root cause is a ~800MB Debian Live ISO used as the boot base, plus a ~2.1GB rootfs with no `--no-install-recommends`. We're replacing the Debian Live dependency entirely with a custom debootstrap-built installer, adding full Archipelago branding to the boot chain, and stripping the rootfs. Target: sub-2GB ISO.

All work on `dev-iso` branch with its own CI workflow. Main branch stays untouched.

---

## Phase 0: Branch + CI Setup

**Create `dev-iso` branch and separate CI workflow.**

1. Branch from current `main`
2. Create `.gitea/workflows/build-iso-dev.yml`:
   - Trigger: `push: branches: [dev-iso]` + `workflow_dispatch`
   - Same structure as `build-iso.yml` (131 lines) but:
     - Remove "Cache Debian Live ISO" step (no longer needed)
     - Add `debootstrap`, `squashfs-tools`, `isolinux`, `syslinux-common`, `mtools`, `grub-efi-amd64-bin`, `grub-pc-bin` to tool dependencies
     - Output naming: `archipelago-dev-unbundled-{date}.iso`
   - Keep: backend build, frontend build, type check, tests, build report
3. Push and verify CI triggers on .228 runner

**Files:**
- New: `.gitea/workflows/build-iso-dev.yml`

---

## Phase 1: Rootfs Size Optimizations

**Shrink rootfs.tar from ~2.1GB to ~1.5GB. Only touches the Dockerfile heredoc in Step 1 (lines 210-335).**

### 1.1 Add `--no-install-recommends`
- Line 229: `apt-get install -y` → `apt-get install -y --no-install-recommends`
- Line 269: Same for Tailscale install
- Explicitly add packages that may be needed as recommends: `fonts-liberation`, `xfonts-base` (for Chromium kiosk)
- **Saves: ~150-300MB**

### 1.2 Remove `firmware-misc-nonfree`
- Line 257: Remove `firmware-misc-nonfree` from package list
- Keep: `firmware-realtek`, `firmware-iwlwifi`, `intel-microcode`, `amd64-microcode`
- **Saves: ~50-80MB**

### 1.3 Strip docs/man/locales
- Add after line 264 (after apt-get clean):
  ```dockerfile
  RUN find /usr/share/doc -depth -type f ! -name copyright -delete 2>/dev/null; \
      find /usr/share/doc -empty -delete 2>/dev/null; \
      rm -rf /usr/share/man /usr/share/info /usr/share/lintian /usr/share/linda; \
      find /usr/share/locale -maxdepth 1 -mindepth 1 ! -name 'en_US' ! -name 'locale.alias' -exec rm -rf {} +
  ```
- **Saves: ~50-80MB**

### 1.4 Remove `wget` and `htop`
- Lines 244, 246: Remove `wget` (curl covers it) and `htop` (luxury tool)
- Keep `git` (used by self-update system)
- **Saves: ~5MB** (minor but removes unnecessary surface)

### Verification
- Build ISO, compare rootfs.tar size
- Boot in QEMU, verify: kiosk renders, SSH works, nginx serves UI, podman runs

**Files modified:**
- `image-recipe/build-auto-installer-iso.sh` (Step 1 Dockerfile heredoc, lines 210-335)

---

## Phase 2: Replace Debian Live with Custom Debootstrap Base

**The big one. Replaces Steps 2, 5, and parts of 4 and 6.**

### 2.1 New Step 2: Build Minimal Installer Environment

Replace lines 420-502 entirely. Run debootstrap inside a container to produce:
- `vmlinuz` — kernel (reused from linux-image-amd64)
- `initrd.img` — custom initramfs with ISO-mount hook
- `filesystem.squashfs` — minimal Debian root (~120-180MB)

The installer squashfs contains only what's needed to run the auto-install script:
- `debootstrap --variant=minbase --include=systemd,systemd-sysv,udev,bash,coreutils,mount,util-linux,cryptsetup,parted,dosfstools,e2fsprogs,kmod,procps,iproute2,ca-certificates,gdisk`
- Auto-login on tty1 via getty override
- systemd service that auto-starts the installer (replaces profile.d hack)

**Key: Custom initramfs hook** (`local-bottom/archipelago-mount`) that:
1. Scans `/dev/sr0`, `/dev/sd*` for a partition containing `archipelago/auto-install.sh`
2. Mounts it read-only at `/run/archiso`
3. This replaces Debian Live's `boot=live components` mechanism

### 2.2 New Step 5: Assemble ISO Directory

Replace lines 2236-2448 entirely. Much simpler — no squashfs overlay mechanism, no tools extraction (tools are in the squashfs), no profile.d manipulation.

New Step 5 just assembles the directory structure:
```
$INSTALLER_ISO/
  live/
    vmlinuz
    initrd.img
    filesystem.squashfs
  boot/grub/
    grub.cfg
    themes/archipelago/  (Phase 3)
    efi.img              (built with grub-mkimage)
  isolinux/
    isolinux.bin
    ldlinux.c32
    isolinux.cfg
  EFI/BOOT/
    BOOTX64.EFI          (built with grub-mkimage)
  archipelago/
    auto-install.sh
    rootfs.tar
    bin/archipelago
    web-ui/
    scripts/
    container-images/    (if bundled)
```

Generate EFI boot image with `grub-mkimage` and ISOLINUX files from the `isolinux` package. No more extracting MBR from Debian Live.

### 2.3 Updated Step 6: ISO Creation

Replace lines 2461-2511 (MBR extraction + EFI image search). Use:
- MBR: `/usr/lib/ISOLINUX/isohdpfx.bin` (from `isolinux` package)
- EFI: `boot/grub/efi.img` (built in Step 5)
- xorriso command stays the same structure

### 2.4 Update Boot Media Paths in Step 4 (auto-install.sh)

Lines 1154-1155: Add `/run/archiso` as first search path:
```bash
for dev in /run/archiso /cdrom /media/cdrom /run/live/medium /lib/live/mount/medium; do
```

Also update lines 2326, 2377 (no longer needed — replaced by systemd service in installer squashfs).

### 2.5 Remove Debian Live cleanup from auto-install.sh

The installed system's auto-install script currently removes `live-boot`, `live-boot-initramfs-tools`, `live-config` (around line 1872). With the custom base, these packages won't exist in the rootfs, so this cleanup becomes a harmless no-op — but should be cleaned up for clarity.

### Verification
- Build ISO, verify size < 2GB
- Boot in QEMU (UEFI mode): verify GRUB menu → installer → full install → reboot
- Boot in QEMU (BIOS mode): verify ISOLINUX → installer → full install → reboot
- After install: SSH, web UI, kiosk, container loading all work
- Test `test-iso-qemu.sh` (may need minor path updates)

**Files modified:**
- `image-recipe/build-auto-installer-iso.sh` (Steps 2, 4, 5, 6 — major rewrite)

---

## Phase 3: Archipelago Boot Branding

**Custom GRUB theme, installer banner, installed system GRUB.**

### 3.1 Create GRUB Theme

New directory: `image-recipe/branding/grub-theme/`
- `theme.txt` — dark background (#0a0a0a), white text, Bitcoin orange (#f7931a) highlight
- `background.png` — 1920x1080 dark with subtle Archipelago logo watermark
- Font files (`.pf2`) — generated with `grub-mkfont` from DejaVu Sans during build

GRUB menu entries:
- "Install Archipelago" (default, quiet boot)
- "Install Archipelago (verbose)" (no `quiet`, for debugging)
- "Boot from local disk" (chainloader)

### 3.2 Create ISOLINUX Theme

New file: `image-recipe/branding/isolinux.cfg`
- Matching dark theme for legacy BIOS boot
- Same menu entries as GRUB

### 3.3 Branded Installer Banner

The systemd service's start script displays:
```
  ARCHIPELAGO BITCOIN NODE OS
  Automatic Installer v0.1.0

  Press Enter to start installation...
```

### 3.4 Install GRUB Theme to Target System

In Step 4 (auto-install.sh), before `update-grub` (around line 1888):
- Copy GRUB theme from ISO to `/mnt/target/boot/grub/themes/archipelago/`
- Add `GRUB_THEME="/boot/grub/themes/archipelago/theme.txt"` to `/mnt/target/etc/default/grub`
- The installed system boots with Archipelago branding, not Debian default

### 3.5 Create Background Image

Render from existing SVG favicon (`neode-ui/public/assets/icon/favico-black-v2.svg`) to PNG at appropriate sizes. Dark background with subtle centered logo.

### Verification
- Boot ISO: GRUB shows Archipelago theme (dark + orange)
- No Debian branding visible anywhere
- After install: target system GRUB also shows Archipelago theme

**Files:**
- New: `image-recipe/branding/grub-theme/theme.txt`
- New: `image-recipe/branding/grub-theme/background.png`
- New: `image-recipe/branding/isolinux.cfg`
- Modified: `image-recipe/build-auto-installer-iso.sh` (Steps 5, 4)

---

## Risk Areas

| Risk | Severity | Mitigation |
|------|----------|------------|
| Custom initramfs fails to find USB media | High | Test multiple USB controller types in QEMU; add verbose fallback boot option |
| Missing packages in minbase break install | Medium | Trace auto-install.sh dependencies; test full install flow |
| GRUB EFI image missing modules | High | Include all common modules in grub-mkimage; test UEFI + BIOS |
| Kiosk breaks without recommends | Medium | Explicitly add Chromium/X11 font deps; test kiosk before merge |
| initramfs overlayfs mount fails | High | Follow well-established patterns from Arch/Ubuntu live ISOs |

---

## Implementation Order

1. **Phase 0** — branch + CI (~1 hour)
2. **Phase 1** — rootfs size opts (~2 hours, push + verify)
3. **Phase 2** — custom base (~8-10 hours, iterative QEMU testing)
4. **Phase 3** — branding (~3 hours)

Phases are sequential — each builds on the previous. Push after each phase, verify CI passes.

---

## Key Files

| File | Role |
|------|------|
| `image-recipe/build-auto-installer-iso.sh` | Main build script — most changes here |
| `.gitea/workflows/build-iso-dev.yml` | New CI workflow for dev-iso branch |
| `image-recipe/branding/grub-theme/*` | New GRUB theme assets |
| `image-recipe/branding/isolinux.cfg` | New ISOLINUX config |
| `image-recipe/test-iso-qemu.sh` | QEMU test script (minor updates) |
| `.gitea/workflows/build-iso.yml` | Reference for new CI workflow |
| `scripts/image-versions.sh` | Unchanged — container image versions |