Packer is an image automation tool used to create identical machine images for multiple platforms from a single configuration. According to virtualization and containerization documentation, Packer typically uses trusted and standardized base images as the starting point for image creation. The most common sources include official operating system images provided by vendors such as Red Hat, Ubuntu, or cloud service providers, and custom images created internally by an organization.

Using official images ensures that the base system is secure, properly maintained, and compliant with vendor standards. Organizations often build custom base images to enforce internal security policies, hardening standards, and preinstalled software, which Packer then extends into environment-specific images.

Physical servers are not considered common or practical base sources for Packer, as Packer operates on machine image artifacts rather than cloning live hardware systems. Images from untrusted sources are explicitly discouraged in virtualization documentation due to security and compliance risks.

Therefore, documentation clearly supports custom organizational images and official operating system images as the correct and recommended base sources for Packer image creation.