Add Packer configuration to build a minimal Alpine 3.23 UEFI VM for XCP-ng tests

packer/.gitignore

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+export

packer/README.md

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+# Packer: Alpine 3.23 Minimal UEFI for XCP-ng
+
+Builds a minimal Alpine Linux 3.23.4 VM image (XVA, zstd-compressed) for use
+in xcp-ng-tests. The image is UEFI-booted, has the XCP-ng guest tools
+installed, and allows root SSH access using the xcp-ng CI public keys.
+
+## VM Specs
+
+| Property    | Value                        |
+|-------------|------------------------------|
+| OS          | Alpine Linux 3.23.4 (x86_64) |
+| vCPUs       | 1                            |
+| RAM         | 256 MiB                      |
+| Disk        | 512 MiB                      |
+| Boot        | UEFI (grub + GPT)            |
+| Network     | DHCP (eth0)                  |
+| Format      | XVA (zstd)                   |
+| Guest tools | xe-guest-utilities (apk)     |
+
+## Prerequisites
+
+### On the machine running Packer
+
+- [Packer](https://developer.hashicorp.com/packer) (tested with v1.x)
+- The `xenserver-iso` builder plugin from
+  [xenserver/packer-plugin-xenserver](https://github.com/xenserver/packer-plugin-xenserver)
+- Python 3 with `libarchive-c==5.3` (for zstd post-processing):
+
+  ```sh
+  pip install 'libarchive-c==5.3'
+  ```
+
+### On the XCP-ng host
+
+- An ISO SR where Packer can upload the Alpine ISO (the plugin uploads it
+  automatically if you use `iso_url`)
+- A network accessible from the build machine; the default variable value is
+  `Pool-wide network associated with eth0` — override with `network_name` if
+  needed
+
+## Building
+
+```sh
+cd packer/
+packer init alpine-3.23-uefi.pkr.hcl
+packer build \
+  -var xen_host=<XCP-ng IP or hostname> \
+  -var xen_password=<XCP-ng root password> \
+  alpine-3.23-uefi.pkr.hcl
+```
+
+Optional overrides:
+
+```sh
+  -var xen_username=root           # default: root
+  -var network_name="<name>"       # default: Pool-wide network associated with eth0
+  -var root_password=<password>    # temporary build password; default: packer
+```
+
+The output XVA is written to:
+
+```
+output-alpine-3.23-uefi/alpine-3.23-uefi.xva
+```
+
+After the build the post-processor rewrites it in-place with zstd compression
+and sets the bridge to `xenbr0`.
+
+## Directory structure
+
+```
+packer/
+├── alpine-3.23-uefi.pkr.hcl  # Packer build definition (HCL)
+├── http_files/
+│   └── answers.txt           # Alpine setup-alpine answerfile
+└── scripts/
+    └── cleanup.sh            # Post-install cleanup run inside the VM
+```
+
+## Notes
+
+- The Alpine guest tools ISO `install.sh` script does not support Alpine;
+  `xe-guest-utilities` is installed from the Alpine community repository
+  instead.
+- `ROOTSSHKEY` in `answers.txt` injects the xcp-ng CI public keys during
+  installation, so no separate provisioner step is needed for SSH keys.
+- `USE_EFI=1` is passed on the kernel cmdline via `boot_command`; this makes
+  `setup-disk` use grub and a GPT layout automatically.
+- Swap is disabled (`SWAP_SIZE=0`) to keep the image within 512 MiB.
+
+## Troubleshooting
+
+**Boot hangs / VNC never gets past the boot prompt**
+: Increase `boot_wait` in the JSON (default `10s`) and ensure VNC is
+  reachable from the Packer host.
+
+**SSH timeout**
+: The install takes up to ~3 minutes on a busy host. Increase
+  `ssh_wait_timeout` if needed.
+
+**Disk full during install**
+: If `setup-disk` fails due to space, the disk size can be bumped to 1024 MB
+  by passing `-var disk_size=1024` — but note that the builder does not expose
+  this directly; you would need to edit the JSON.
+
+**xva_bridge.py fails**
+: Ensure `libarchive-c==5.3` is installed. Other versions may not work due to
+  internal API usage.

packer/alpine-3.23-uefi.pkr.hcl

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+packer {
+  required_plugins {
+    xenserver = {
+      version = ">= v0.11.0"
+      source  = "github.com/vatesfr/xenserver"
+    }
+  }
+}
+
+variable "xen_host" {
+  type        = string
+  description = "XCP-ng pool master hostname or IP"
+}
+
+variable "xen_username" {
+  type        = string
+  description = "XCP-ng SSH username"
+  default     = "root"
+}
+
+variable "xen_password" {
+  type        = string
+  description = "XCP-ng SSH password"
+  sensitive   = true
+}
+
+variable "network_name" {
+  type        = string
+  description = "Name of the XCP-ng network to attach the VM to"
+  default     = "Pool-wide network associated with eth0"
+}
+
+variable "sr_name" {
+  type        = string
+  description = "Name of the SR to store the VM disk on (defaults to pool default)"
+  default     = ""
+}
+
+variable "sr_iso_name" {
+  type        = string
+  description = "Name of the ISO SR to upload the Alpine ISO to (defaults to pool default)"
+  default     = ""
+}
+
+variable "root_password" {
+  type        = string
+  description = "Temporary root password set during the build"
+  default     = "vateslab"
+  sensitive   = true
+}
+
+source "xenserver-iso" "alpine" {
+  remote_host     = var.xen_host
+  remote_username = var.xen_username
+  remote_password = var.xen_password
+
+  vm_name         = "alpine-3.23-uefi"
+  vm_description  = "Alpine Linux 3.23.4 minimal UEFI - built with Packer"
+  vcpus_max       = 1
+  vcpus_atstartup = 1
+  vm_memory       = 256
+  disk_size       = 512
+
+  firmware       = "uefi"
+  clone_template = "Other install media"
+
+  network_names = [var.network_name]
+
+  sr_name     = var.sr_name
+  sr_iso_name = var.sr_iso_name
+
+  iso_url      = "https://dl-cdn.alpinelinux.org/alpine/v3.23/releases/x86_64/alpine-standard-3.23.4-x86_64.iso"
+  iso_checksum = "sha256:cfef39c7954f7c4447bcb321b9f4a1cef834536a321309d2c31275d9f2475a4e"
+
+  http_directory = "http_files"
+  boot_wait      = "30s"
+  boot_command = [
+    "root<enter>",
+    "<wait3>",
+    "ifconfig eth0 up && udhcpc -i eth0<enter><wait5>",
+    # "USE<leftShiftOn>-<leftShiftOff>EFI=1 SWAP<leftShiftOn>-<leftShiftOff>SIZE=0 ERASE<leftShiftOn>-<leftShiftOff>DISKS=/dev/xvda setup-alpine -f http://{{.HTTPIP}}:{{.HTTPPort}}/answers.txt<enter>",
+    "USE<leftShiftOn>-<leftShiftOff>EFI=1 SWAP<leftShiftOn>-<leftShiftOff>SIZE=0 ERASE<leftShiftOn>-<leftShiftOff>DISKS=/dev/xvda setup-alpine -f https://raw.githubusercontent.com/xcp-ng/xcp-ng-tests/refs/heads/gln/packer-alpine-uefi-xcpng-loun/packer/http_files/answers.txt<enter>",
+    "<wait10>",
+    "${var.root_password}<enter>",
+    "<wait>",
+    "${var.root_password}<enter>",
+    "<wait60>",
+    "apk add --no-cache xe-guest-utilities<enter>",
+    "rc-update add xe-guest-utilities default<enter>",
+    # "rc-service xe-guest-utilities start<enter>",
+    # Remove log files
+    "find /var/log -type f -exec truncate -s 0 {} \\;<enter>",
+    # Remove temporary files
+    "rm -rf /tmp/* /var/tmp/*<enter>",
+    # Clear machine-id so each clone gets a unique one
+    "echo > /etc/machine-id<enter>",
+    # Remove history
+    "rm -f /root/.ash_history<enter>",
+    "<wait3>",
+  ]
+
+  communicator     = "none"
+  ssh_username     = "root"
+  ssh_password     = var.root_password
+  ssh_wait_timeout = "10m"
+
+  install_timeout  = "30m"
+  output_directory = "export"
+  keep_vm          = "never"
+  format           = "xva_zstd"
+}
+
+build {
+  sources = ["xenserver-iso.alpine"]
+}

packer/http_files/answers.txt

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+KEYMAPOPTS=none
+HOSTNAMEOPTS=alpine
+DEVDOPTS=mdev
+INTERFACESOPTS="auto lo
+iface lo inet loopback
+auto eth0
+iface eth0 inet dhcp
+    hostname alpine
+"
+TIMEZONEOPTS=UTC
+PROXYOPTS=none
+APKREPOSOPTS="-1 -c"
+USEROPTS=none
+SSHDOPTS=openssh
+ROOTSSHKEY="ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMnN/wVdQqHA8KsndfrLS7fktH/IEgxoa533efuXR6rw XCP-ng CI
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDKz9uQOoxq6Q0SQ0XTzQHhDolvuo/7EyrDZsYQbRELhcPJG8MT/o5u3HyJFhIP2+HqBSXXgmqRPJUkwz9wUwb2sUwf44qZm/pyPUWOoxyVtrDXzokU/uiaNKUMhbnfaXMz6Ogovtjua63qld2+ZRXnIgrVtYKtYBeu/qKGVSnf4FTOUKl1w3uKkr59IUwwAO8ay3wVnxXIHI/iJgq6JBgQNHbn3C/SpYU++nqL9G7dMyqGD36QPFuqH/cayL8TjNZ67TgAzsPX8OvmRSqjrv3KFbeSlpS/R4enHkSemhgfc8Z2f49tE7qxWZ6x4Uyp5E6ur37FsRf/tEtKIUJGMRXN XCP-ng CI"
+NTPOPTS=none
+DISKOPTS="-m sys /dev/xvda"
+LBUOPTS=none
+APKCACHEOPTS=none

packer/scripts/cleanup.sh

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+#!/bin/sh
+set -e
+
+# Remove apk cache
+rm -rf /var/cache/apk/*
+
+# Remove log files
+find /var/log -type f -exec truncate -s 0 {} \;
+
+# Remove temporary files
+rm -rf /tmp/* /var/tmp/*
+
+# Clear machine-id so each clone gets a unique one
+printf '' > /etc/machine-id 2>/dev/null || true
+
+# Remove history
+rm -f /root/.ash_history /root/.bash_history