packer-cn/website/source/partials/common/_ISOConfig.html.md

By default, Packer will symlink, download or copy image files to the Packer cache into a "hash($iso_url+$iso_checksum).$iso_target_extension" file. Packer uses hashicorp/go-getter in file mode in order to perform a download.

go-getter supports the following protocols:

• Local files
• Git
• Mercurial
• HTTP
• Amazon S3

~> On windows - when referencing a local iso - if packer is running without symlinking rights, the iso will be copied to the cache folder. Read Symlinks in Windows 10 ! for more info.

Examples: go-getter can guess the checksum type based on iso_checksum len.

{
  "iso_checksum": "946a6077af6f5f95a51f82fdc44051c7aa19f9cfc5f737954845a6050543d7c2",
  "iso_url": "ubuntu.org/.../ubuntu-14.04.1-server-amd64.iso"
}

{
  "iso_checksum_type": "file",
  "iso_checksum": "ubuntu.org/..../ubuntu-14.04.1-server-amd64.iso.sum",
  "iso_url": "ubuntu.org/.../ubuntu-14.04.1-server-amd64.iso"
}

{
  "iso_checksum_url": "./shasums.txt",
  "iso_url": "ubuntu.org/.../ubuntu-14.04.1-server-amd64.iso"
}

{
  "iso_checksum_type": "sha256",
  "iso_checksum_url": "./shasums.txt",
  "iso_url": "ubuntu.org/.../ubuntu-14.04.1-server-amd64.iso"
}