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Add Packer configuration to build a minimal Alpine 3.23 UEFI VM for XCP-ng tests
The image is built with the vatesfr/packer-plugin-xenserver plugin targeting a local XCP-ng host. It produces a zstd-compressed XVA with: - Alpine Linux 3.23.4 (x86_64), UEFI boot (grub + GPT) - 1 vCPU, 256 MiB RAM, 512 MiB disk, no swap - xe-guest-utilities installed from the Alpine community repo - XCP-ng CI public SSH keys authorised for root - Post-processed by xva_bridge.py to set bridge=xenbr0 and zstd compression Signed-off-by: Gaëtan Lehmann <gaetan.lehmann@vates.tech>
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‎packer/.gitignore‎

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export

‎packer/README.md‎

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

‎packer/alpine-3.23-uefi.pkr.hcl‎

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

‎packer/http_files/answers.txt‎

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

‎packer/scripts/cleanup.sh‎

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

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