The module descriptions sit in `examples/` inside the control plane, and
that name has been doing harm: everything there reads as a sketch, and
one shipped naming a container image nothing builds. A directory called
the catalogue would have made "does this work" the obvious question.
The shape of the answer turns on one measurement. Of the 126 modules in
the system being replaced, 47 are software in their own right — the
largest is 182 source files, and a speech-capture module carries a whole
daemon. Another 44 ship helper scripts. Only 35 are a description and
nothing else.
So a catalogue cannot be a folder of manifests, because two thirds of
modules are programs. That splits them four ways, and only two of the
four belong in a catalogue: things the world made that we describe, and
packages with some files. What the mesh is made of stays in the
repositories that build it. What we wrote keeps its description beside
its code, in the same commit, because nothing else can stop the two
drifting.
The mesh's list of modules is a table, not a repository, and it already
records where each module came from and at which commit. Nothing needs
inventing for modules from anywhere; a repository of ours is just the
source we curate.
The check that a description is valid should move to a command on the
control plane's binary. Today a test reaches into the control plane's
internals to parse manifests, and another reads its build file to check
images exist — two jobs tangled. A command would also give the same
check to somebody describing their own application, which is the case
that matters most and has none.
Left open: how a provisioner's image gets published and pinned, and
whether thirty-five install-a-package modules deserve to be modules at
all.
