Targets

A target names what convert builds: the platform, and implicitly the output format.

Target	Canonical name	Output	Default support image
qemu	qemu-qcow2	qcow2, UEFI-bootable UKI	none
incus	incus-qcow2	qcow2, UEFI-bootable UKI, plus the Incus support image	ghcr.io/contemper-project/incus-support:v1

qemu is the reference target. It adds nothing to your image, and the disk boots under any QEMU with UEFI firmware and nothing else. It is the debugging baseline, and what deploy --to local-qemu is for.

incus builds the same disk format, since Incus runs VMs on QEMU with OVMF firmware. It differs in the support image layered on top, by default ghcr.io/contemper-project/incus-support:v1. It adds the guest side of the Incus agent: the agent is copied from the share Incus attaches to the VM and started at boot. The support image declares systemd and OpenRC variants and picks the one that matches your image's init system, so an image with neither fails the conversion with a message naming the branch.

The tag v1 floats within the support image's major version, which is the interface contract between contemper and its support images. The bundle manifest records the digests it resolved to. To use a different support image, or a pinned digest, pass --support <ref>; it replaces the default (see below).

Default support images

Each target may declare a default support image: the reference used when --target alone is given, with no --support. It's how incus means "qcow2 plus the Incus agent" without you having to name the image yourself.

qemu has no default support image. --support <ref> replaces the target's default outright; it never stacks with it. There is no flag to merge both an explicit support image and the target's default in one build - a target's own support image is free to declare variants for the things it needs to adapt to (see Support images), which covers the common case of wanting the default plus something conditional.

The bundle manifest and the progress output both record which one applied: contemper.json's support.origin is "target" when the default was used, "flag" when --support replaced it. See Bundle manifest.

Names and aliases

Where a platform needs more than one format, it's a suffix on the target name, incus-qcow2 vs. incus-raw, in the spirit of Packer's builder naming. The unsuffixed name is an alias for that platform's default. One flat namespace, rather than platform and format as independent axes, avoids a large surface of mostly meaningless combinations.

Both spellings work. The suffixed one is canonical, and it's what the progress output and the bundle manifest record: --target incus is reported as incus-qcow2. A platform's default format won't change under you, since that would silently alter what your pipeline produces, so it's treated as a breaking change.

Targets and providers

A target is what convert builds: which support image went in, and which format came out. A provider is where a bundle goes afterwards: local-qemu, an Incus server. They are separate on purpose. An incus-qcow2 bundle boots fine under local-qemu; the target records what went into the disk, not where it may run.