fixture

Documentation

Overview

Package fixture packs a host directory into a read-only ext4 filesystem image for attaching to a VM as a block device (ADR-0015). It is the only fleetbox package that imports the ext4 writer (go-ext4fs); the seed ISO stays on cloudiso. Fixtures are read-only copy-in, not live mounts — see ADR-0015 for the reasoning (cloud-hypervisor has no daemon-free live-share path).

Index

• func BuildImage(imgPath, srcDir, label string) error

Functions

func BuildImage

func BuildImage(imgPath, srcDir, label string) error

BuildImage packs the directory tree at srcDir into a fresh ext4 filesystem image at imgPath, labeled label (the guest mounts the image by LABEL). Every file is written world-readable (0444), every directory traversable (0555), owned by root, so any guest user can read the whole tree; host permission and executable bits are not preserved. Symlinks are copied as symlinks; special files (device nodes, pipes, sockets) are rejected with an error.

The image is built on a 16 GiB sparse canvas and then resized down to fit its content, so a typical fixture lands at a few MiB on disk. A payload larger than 16 GiB is unsupported (the resize ceiling).