# Archiso — Custom Live Installer

The archiso build system produces a bootable Arch Linux ISO pre-loaded with the M-Archy installer scripts. Optionally, an answerfile can be embedded so the entire install — base OS + dotfiles — runs with zero user interaction.

---

## Prerequisites

```bash
sudo pacman -S archiso jq
```

---

## Building the ISO

```bash
# Basic build — interactive installer, no answerfile
bash setup/archiso/build.sh

# Specify output directory
bash setup/archiso/build.sh /path/to/output

# Embed an answerfile for automated deployment
bash setup/archiso/build.sh --preconf

# Embed a specific answerfile
bash setup/archiso/build.sh --preconf ~/my-server.json

# Both flags together
bash setup/archiso/build.sh --preconf ~/my-server.json /media/usb/output
```

| Flag | Effect |
|------|--------|
| _(none)_ | Clean ISO, no answerfile |
| `--preconf` | Embed `~/answerfile.json` at `/answerfile.json` in the ISO |
| `--preconf FILE` | Embed the specified file instead |

Build artefacts land in `~/m-archy-out/` by default. Override with the `OUT_DIR` environment variable or by passing a path argument.

### Environment Variables

| Variable | Default | Purpose |
|----------|---------|---------|
| `WORK_DIR` | `~/m-archy-build` | Scratch space for mkarchiso |
| `OUT_DIR` | `~/m-archy-out` | ISO output directory |

---

## What the Build Does

1. Copies the upstream `releng` Arch base profile
2. Applies the M-Archy overlay (`setup/archiso/overlay/`)
3. Replaces `profiledef.sh` with the M-Archy version
4. Adds extra packages from `packages.extra`
5. Embeds both installer scripts (`arch-autoinstall.sh`, `archbaseos-guided-install.sh`) into `/root/installer/`
6. If `--preconf`: copies the answerfile to `/answerfile.json` in the ISO's airootfs
7. Runs `mkarchiso` to produce the final `.iso`

---

## Extra Packages on the Live System

Defined in `setup/archiso/overlay/packages.extra`:

```
git
jq
pam-u2f
btop
fastfetch
openssh
```

These are added on top of the standard Arch `releng` package set.

---

## Live System Entry Points

Once booted from the ISO, the following are available:

### `install-arch`

A command placed in `/usr/local/bin/`:

```bash
install-arch           # guided mode (default)
install-arch guided    # guided interactive install
install-arch auto      # automated mode (reads /answerfile.json)
```

### `/root/launch.sh`

Internal dispatcher used by `install-arch`.

### `/answerfile.json`

Only present when built with `--preconf`. Both installer scripts check for this file on startup. If found, all prompts are answered from it — the only interaction required is the disk-encryption password (passwords are never stored in answerfiles).

---

## Automated Deployment Workflow

```
┌─────────────────────────────────────┐
│  Developer machine                  │
│                                     │
│  1. generate-answerfile.sh          │
│     → ~/answerfile.json             │
│                                     │
│  2. build.sh --preconf              │
│     → ~/m-archy-out/m-archy.iso     │
│                                     │
│  3. dd if=m-archy.iso of=/dev/sdX   │
└──────────────┬──────────────────────┘
               │ USB
               ▼
┌─────────────────────────────────────┐
│  Target machine (boots from USB)    │
│                                     │
│  4. install-arch auto               │
│     reads /answerfile.json          │
│     installs base OS                │
│     runs tui-install.sh in chroot   │
│     installs dotfiles & apps        │
│                                     │
│  5. Reboot → ready system           │
└─────────────────────────────────────┘
```

For multi-machine deployments, the `hostname` field in the answerfile is combined with the machine's MAC address, so each system gets a unique hostname even though they share the same answerfile.

---

## Overlay Structure

```
setup/archiso/overlay/
├── airootfs/
│   ├── etc/motd                          # Welcome message
│   ├── root/
│   │   └── launch.sh                     # Installer entry point
│   └── usr/local/bin/
│       └── install-arch                  # User-facing CLI command
├── packages.extra                        # Additional live-system packages
└── profiledef.sh                         # M-Archy ISO profile definition
```

The `build.sh` script also adds at build time:
```
airootfs/root/installer/
├── arch-autoinstall.sh
└── archbaseos-guided-install.sh
```

---

## Writing the ISO to USB

```bash
# Find the USB drive
lsblk

# Write (replace /dev/sdX with your drive — ALL DATA WILL BE ERASED)
sudo dd if=~/m-archy-out/m-archy-*.iso of=/dev/sdX bs=4M status=progress oflag=sync
```

Or use `ventoy` / `balenaEtcher` as alternatives.