ADR 0048 named ingress as an unclosed hole -- nothing said what terminates
TLS, how a public name reaches a container, or which tier owned it. Resolving
it needed no new concepts, which is why it survived: nobody had applied the
rules already written to it.
Ingress is not substrate. The control plane does not need a route to start,
and no node needs one to reach it -- the node dials out and has no listening
control surface. It grants itself a route afterwards, like a bucket.
A route is an instantiation edge under ADR 0044. The direction mirrors a
database -- the consumer supplies a target and receives a name rather than
credentials -- but it is the same edge.
The substantive finding is that exposure is three facts at two scopes: name
resolution and certificate issuance need to know which node is publicly
reachable, and only the proxy mapping is a single machine's business. That is
why it belongs to the connectivity context, and why Traefik doing all three on
the node is wrong.
Which matters beyond tidiness: research 006 counted traefik as one of two
modules opening a direct Postgres connection, reading nodes and mesh_ca. That
violates 0037, 0045 and 0039 at once, and is why every node permanently holds
a credential to the control plane's database. Deriving the config centrally and
delivering it as `file` resources removes it, costs zero new host vocabulary,
and closes the set 0039 identified -- wireguard was the other.
Left open deliberately: the mesh's internal CA is the other thing traefik
reads, and it belongs to the link's mutual authority, not to exposure.
Conflating the two is what made the gap hard to see.
Also fixes an inconsistency from the previous commit: 06 still claimed the
virtual host was raised from the bundle.
Proposed, not accepted -- for review.
The design layer described every service by role and never once by name:
Postgres appeared in zero design documents. That was over-application of the
research rule "never identify the mesh it observed", which is about node names
and domains, not software.
Two things were actually broken by it. substrate.lock pins images by digest and
a digest belongs to a named image, so the bundle could not be written from the
design. And a reader could not tell a settled choice from an unexamined one --
"a relational store" reads identically either way.
ADR 0048 names them: PostgreSQL, LavinMQ, MinIO, an OCI registry, Docker. The
argument for each is continuity, which is a real argument -- replacing a
substrate service migrates the mesh's own state. Role and product are now both
written, because the design depends on the protocol while the installer needs
the product.
Also separates two questions the substrate doc had merged: being substrate and
being in the bundle. Only Postgres must precede the control plane; the rest are
substrate by role and ordinary by delivery. Whether the bus joins it is left
open, because it turns on the control plane's internal shape.
Names the forge as Gitea, and records ingress/Traefik as an unclosed gap rather
than a naming one -- nothing says what terminates TLS or which tier owns it.
Fixes a miscount: the host's bootstrap vocabulary is six shapes, not five.
Nineteen files, seventy-nine mentions, no definition. That is how-we-build §5
failing on this repository's own vocabulary — ubiquitous language is checked,
not assumed.
The definition, and it is not arbitrary: the control plane is everything that
needs to know about MORE THAN ONE NODE. It follows from ADR 0037, which has the
host applying rather than deciding precisely because deciding needs knowledge
the machine does not have. So the line falls exactly there — writing a file is
the host's, choosing which nodes run the store is the control plane's, and
anything a single machine could answer alone does not belong here at all.
That last consequence is worth having: putting a single-machine concern in tier
2 is a mistake the tier rule will NOT catch, because the dependency direction
stays correct.
Also states what it is not — not the thing that changes machines, not a surface,
not the substrate, and not privileged on a node beyond what the declaration
vocabulary allows. And the property that makes tier 2 unlike the others: it is
itself a consumer, with the same requirements as any module, which is the
circularity the bundle exists to resolve rather than hide.
Scoped deliberately: this defines the term and does not design the contexts
inside it. Ten is the skeleton's claim rather than a settled list, and research
006 still asks whether the record belongs here or in the substrate.
jschoubben