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Overview

An OS bundle is a self-describing archive containing the base operating system image (rootfs and/or initramfs) along with metadata describing the update strategy, slot detection, verification, and partition layout.

When OS Bundles Are Used​

A runtime manifest may optionally include an os_bundle reference. When a runtime with a different os_build_id than the running system is activated, the OS bundle update process is triggered automatically.

Relationship to Runtimes​

OS bundles are referenced by image_id in the runtime manifest and stored as .raw files in the shared image pool (/var/lib/avocado/images/) alongside extension images. A runtime may or may not include an OS bundle -- runtimes that only update extensions do not need one.

OS Bundle Files​

OS bundles are distributed as .aos files (tar.zst compressed archives) containing:

  • bundle.json -- Update metadata and configuration. See Bundle Format for the full specification.
  • Artifact files -- The actual rootfs and/or initramfs images to be written to partitions.