vimto

vimto

vimto is a virtual machine testing orchestrator for the Go toolchain. It allows you to easily run Go unit tests using a specific Linux kernel.

# With .vimto.toml in place:
vimto -- go test .
# Otherwise:
vimto -kernel /path/to/vmlinuz -- go test .

It's possible to obtain the kernel from a container image (requires Docker).

vimto -kernel example.org/reg/image:tag -- go test .

Finally, you can also use a path to a directory:

vimto -kernel /path/to/dir -- go test .

vimto expects the kernel to be at /boot/vmlinuz for containers and directories. See also Container format.

Installation

Install using the Go toolchain:

CGO_ENABLED=0 go install lmb.io/vimto@latest

Configuration

vimto reads a configuration file .vimto.toml in TOML format, either from the current directory or from the root of the git repository enclosing the current directory.

All available options and their values are in testdata/default.toml.

Container format

The container (or directory) must contain a file /boot/vmlinuz which is used to boot the VM.

Other files and directories in the container are merged with the host filesystem using an overlayfs mount inside the VM.

Error: directory /lib: shadows symlink on host

This error is generated if the image contains a directory that would shadow important directories in the host:

• /lib
• /lib64
• /bin
• /sbin

This happens when running on distributions that have completed a /usr merge. In this case these directories are symlinks on the host. Overlaying a directory from the image will make the symlink disappear.

To work around the issue, place files in /usr/lib, ... and include your own /lib -> /usr/lib symlink in the image.

Currently not supported

• Networking
• Interactive shell sessions

Requirements

• A recent version of qemu (8.1.3 is known to work)
• A Linux kernel with the necessary configuration (>= 4.9 is known to work)
• Docker (optional, to fetch kernels from OCI registries)

Here is a non-exhaustive list of required Linux options:

• CONFIG_9P_FS=y
• CONFIG_DEVTMPFS=y
• CONFIG_NET_9P_VIRTIO=y
• CONFIG_NET_9P=y
• CONFIG_NET_CORE=y
• CONFIG_OVERLAY_FS=y
• CONFIG_PCI=y
• CONFIG_SYSFS=y
• CONFIG_TMPFS=y
• CONFIG_TTY=y
• CONFIG_UNIX=y
• CONFIG_UNIX98_PTYS=y
• CONFIG_VIRTIO_CONSOLE=y
• CONFIG_VIRTIO_MMIO=y
• CONFIG_VIRTIO_NET=y
• CONFIG_VIRTIO_PCI=y
• CONFIG_VIRTIO=y
• CONFIG_VT=y