The blocking question was where a container image comes from, and the version
that blocked assumed the machine might have no network. That assumption came
from the LAB: a scenario is a closed address space by design, which is what lets
two scenarios hold the same addresses without meeting. Production is not sealed
— a machine being adopted has a network, and one that does not is a machine
where very little works anyway.
So substrate.lock carries references, not payload: an image name and a digest,
fetched at apply time. A first node pulls from upstream because no mesh registry
exists yet; every node after that pulls from the mesh's own. The lab is the
exception and places images itself, the way it already places the host binary —
a property of a test environment, and letting it dictate the production design
would be the tail wagging the dog.
Pinned by DIGEST rather than tag. Reproducibility comes from pinning the
identity of a thing, not from carrying its bytes, which is what makes fetching
acceptable rather than a compromise.
ADR 0041 survives untouched, which was the point. "Copy it onto a machine and
run it" stays literally true — one binary, a few megabytes, which then fetches
what it was told to. Carrying images would have quietly redefined the property
that decision rests on.
Costs accepted and named: an apply can now fail because something is
unreachable, which a self-contained artifact could not, so it must fail legibly
— naming what it could not fetch and from where. And the lab needs a way to
place images into a machine that also has no container runtime, both of which
are lab-installation concerns and neither solved here.
Research 012's build-time-versus-apply-time reframing narrows accordingly: it
still holds for what a tailored installer contains, and no longer has to hold
for images.
jschoubben
5b3d0ebd4f