Create and Import Local Images using Packer

Overview

Packer is a lightweight open-source tool for automatic image packaging launched by Hashicorp Company (for more details, refer to the previous document). UCloud Global now supports one-click importing of homemade local images into the UCloud Global cloud platform thanks to the integration of Packer.

Image Import Example

Next, a CentOS image will be created and imported using Packer. It is shown below:

Packer first makes a RAW image using QEMU Builder, stored in a local directory specified by user, and then uses import Post-Processors to store the local image to a UFile specified by user, and automate the import into the UCloud Global cloud platform.

Environment setup

Installing Packer

Follow the official installation document to install Packer

Configure default User

Set keys TEST_PUBLIC_KEY, TEST_PRIVATE_ KEY and project ID TEST_PROJECT_ID as global environment variables (recommended), or specify public_key、 private_key、 project_id explicitly in the json file.

Installing QEMU

Follow the official installation document, you can use command line to install, MacOS: brew install qemu, CentOs: yum install qemu-kvm, Ubuntu: apt-get install qemu

Creating a UFile bucket

Follow the official document

Writing JSON File

We use the creation and import of a custom CentOS 6.10 image on MacOs as an example. Firstly, create a clean empty folder as a workspace, switch to that directory, and write a JSON spec file (eg：local.json), as follows ：

{"variables": {
  "test_public_key": "{{env `TEST_PUBLIC_KEY`}}",
  "test_private_key": "{{env `TEST_PRIVATE_KEY`}}",
  "test_project_id": "{{env `TEST_PROJECT_ID`}}",
  "disk_size": "4096",
  "iso_checksum": "0da4a1206e7642906e33c0f155d2f835",
  "iso_checksum_type": "md5",
  "iso_name": "CentOS-6.10-x86_64-minimal.iso",
  "ks_path": "centos-6.10/ks.cfg",
  "mirror": "http://mirrors.ustc.edu.cn/centos",
  "mirror_directory": "6.10/isos/x86_64",
  "template": "centos-6.10-x86_64"
},
  "builders":[
    {
      "type": "qemu",
      "boot_command": [
        "<tab> text ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/{{user `ks_path`}}<enter><wait>"
      ],
      "boot_wait": "10s",
      "disk_size": "{{user `disk_size`}}",
      "http_directory": "http",
      "iso_checksum": "{{user `iso_checksum`}}",
      "iso_checksum_type": "{{user `iso_checksum_type`}}",
      "iso_url": "{{user `mirror`}}/{{user `mirror_directory`}}/{{user `iso_name`}}",
      "output_directory": "packer-{{user `template`}}-qemu",
      "shutdown_command": "echo 'packer'|sudo -S shutdown -P now",
      "ssh_password": "test_packer",
      "ssh_port": 22,
      "ssh_username": "root",
      "ssh_timeout": "10000s",
      "vm_name": "{{ user `template` }}.raw",
      "net_device": "virtio-net",
      "disk_interface": "virtio",
      "format": "raw",
      "use_default_display": "false",
      "qemuargs": [
        ["-display", "cocoa"]
      ]
    }
  ],
  "post-processors":[
    {
      "type":"import",
      "public_key": "{{user `test_public_key`}}",
      "private_key": "{{user `test_private_key`}}",
      "project_id": "{{user `test_project_id`}}",
      "region":"cn-bj2",
      "ufile_bucket_name": "packer-test",
      "image_name": "packer_import_test",
      "image_os_type": "CentOS",
      "image_os_name": "CentOS 6.10 64bits",
      "format": "raw"
    }
  ]
}

This sets up a qemu Builder and an import Post-Processors, where the UFile bucket name and other information are configured.

Writing Kickstart Files

According to the http_directory and boot_command configured in the JSON file above for QEMU, you need to create a ./http/centos-6.10/ directory under the JSON file directory to store the Kickstart file, i.e., ks.cfg, as follows: (Kickstart reference document)

install
cdrom
lang en_US.UTF-8
keyboard us
network --bootproto=dhcp
rootpw test_packer
firewall --disabled
selinux --permissive
timezone UTC
unsupported_hardware
bootloader --location=mbr
text
skipx
zerombr
clearpart --all
autopart
auth --enableshadow --passalgo=sha512
firstboot --disabled
reboot

%packages --nobase --ignoremissing
sudo
gcc
make
%end

Running Command Line

By running the command packer build local.json, you can create and import a custom image in one click.

Create Custom Images with Packer Image Upload