BootImages

BootImages are machine-readable images that contain all components necessary to boot a computer or device. They typically include a bootloader, a kernel, and a root filesystem or a mechanism to load it. They are used across desktops, servers, embedded systems, and virtualization for provisioning and booting.

There are several formats and variants: ISO images used with optical media or bootable USB; IMG and raw disk images that can be written to storage; compressed archive images; and specialized formats for virtualization (QCOW2, VMDK), container-like cloud images, and bootable EFI or BIOS-specific images. In many environments, boot images are designed to be network-bootable using PXE or iPXE.

Creation and maintenance: Building a boot image involves selecting a kernel, a bootloader (GRUB, systemd-boot), and a filesystem with essential drivers and tools. For Linux, initramfs or initrd is included to mount the root filesystem during early boot. Image pipelines may also incorporate cloud-init or equivalent for post-deployment configuration. Images are versioned, tested, and stored in image registries or catalogs.

Deployment and use cases: BootImages enable rapid provisioning of new systems, disaster recovery, testing multiple configurations, and deploying embedded devices. They can be deployed via USB/SD cards, optical media, network boot (PXE), or through cloud and virtualization platforms where prebuilt images are used to boot instances.

Security and governance: Best practices include cryptographic signing and verification, checksums, secure boot compatibility, and measured boot policies. Regular updates and strict provenance controls reduce drift and vulnerabilities.

See also: Bootloader, Kernel, Initramfs, PXE, Cloud image.