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16.1 image Reference

The image record, described right after, allows you to define a customized bootable system image.

Data Type: image

This is the data type representing a system image.

name (default: #false)

The image name as a symbol, 'my-iso9660 for instance. The name is optional and it defaults to #false.


The image format as a symbol. The following formats are supported:

  • disk-image, a raw disk image composed of one or multiple partitions.
  • compressed-qcow2, a compressed qcow2 image composed of one or multiple partitions.
  • docker, a Docker image.
  • iso9660, an ISO-9660 image.
  • tarball, a tar.gz image archive.
  • wsl2, a WSL2 image.
platform (default: #false)

The platform record the image is targeting (see Platforms), aarch64-linux for instance. By default, this field is set to #false and the image will target the host platform.

size (default: 'guess)

The image size in bytes or 'guess. The 'guess symbol, which is the default, means that the image size will be inferred based on the image content.


The image’s operating-system record that is instantiated.

partition-table-type (default: 'mbr)

The image partition table type as a symbol. Possible values are 'mbr and 'gpt. It default to 'mbr.

partitions (default: '())

The image partitions as a list of partition records (see partition Reference).

compression? (default: #true)

Whether the image content should be compressed, as a boolean. It defaults to #true and only applies to 'iso9660 image formats.

volatile-root? (default: #true)

Whether the image root partition should be made volatile, as a boolean.

This is achieved by using a RAM backed file system (overlayfs) that is mounted on top of the root partition by the initrd. It defaults to #true. When set to #false, the image root partition is mounted as read-write partition by the initrd.

shared-store? (default: #false)

Whether the image’s store should be shared with the host system, as a boolean. This can be useful when creating images dedicated to virtual machines. When set to #false, which is the default, the image’s operating-system closure is copied to the image. Otherwise, when set to #true, it is assumed that the host store will be made available at boot, using a 9p mount for instance.

shared-network? (default: #false)

Whether to use the host network interfaces within the image, as a boolean. This is only used for the 'docker image format. It defaults to #false.

substitutable? (default: #true)

Whether the image derivation should be substitutable, as a boolean. It defaults to true.

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