Build a OS image with Packer and QEMU

build-a-os-image-with-packer-and-qemu.md

Build a OS image with QEMU and Ubuntu Cloud Image

Prerequirements

• Packer
• QEMU
• Docker

Build an image of cloud-init settings

$ docker run -it -v `pwd`:/tmp/host --rm ubuntu:16.04

# apt update
# apt install -y vim cloud-utils
# cloud-localds /tmp/host/cloud.img /tmp/host/cloud.cfg

Build a OS image with Packer

$ packer build template.json

cloud.cfg

#cloud-config
password: ubuntu
ssh_pwauth: true
chpasswd:
  expire: false

template.json

{
  "builders":
  [
    {
      "type": "qemu",
      "iso_url": "ubuntu-16.04-server-cloudimg-amd64-disk1.img",
      "iso_checksum": "3a4b7f6115ca074c4728e4628ca73160e6b7ef6995db3c382015545940568939",
      "iso_checksum_type": "sha256",
      "disk_image": true,
      "output_directory": "image",
      "disk_size": 5000,
      "format": "qcow2",
      "disk_compression": true,
      "headless": true,
      "accelerator": "none",
      "ssh_username": "ubuntu",
      "ssh_password": "ubuntu",
      "ssh_port": 22,
      "ssh_wait_timeout": "300s",
      "vm_name": "ubuntu",
      "use_default_display": true,
      "qemuargs": [
        ["-m", "2048M"],
        ["-smp", "2"],
        ["-fda", "cloud.img"],
        ["-serial", "mon:stdio"]
      ]
    }
  ]
}

This is working for me, in case someone like me hit this

{
  "builders": [
    {
      "type": "qemu",
      "iso_url": "ubuntu-22.04-server-cloudimg-amd64.img",
      "iso_checksum": "md5:9688fc9011dcd4d960620d2ebb98a639",
      "ssh_username": "ubuntu",
      "ssh_password": "a",
      "ssh_timeout": "1m",
      "ssh_port": 2222,
      "skip_nat_mapping": true,
      "disk_size": "40G",
      "disk_image": true,
      "disk_compression": true,
      "format": "qcow2",
      "headless": true,
      "accelerator": "kvm",
      "output_directory": "images",
      "qemuargs": [
        [ "-machine", "accel=kvm,type=q35" ],
        [ "-cpu", "host" ],
        [ "-m", "2G" ],
        [ "-smp", "2" ],
        [ "-nographic" ],
        [ "-device", "virtio-net-pci,netdev=net0" ],
        [ "-netdev", "user,id=net0,", "hostfwd=tcp::2222-:22" ],
        [ "-cdrom", "seed.img" ]
      ],
      "shutdown_command": "echo a |sudo -S shutdown -P now",
      "boot_command": [],
      "vm_name": "jammy"
    }
  ]
}

keypoint is

• set port forward
• use -cdrom