How to use Packer to build a Windows Server template for VMware vSphere

Note: this story is compatible with Packer v1.5.x or previous versions. For Packer v1.6.x versions, please look to this story.

Packer is an open-source tool used to create virtual machine templates from a .json file.

To automatize the creation of templates in VMware vSphere, there are two major approaches: