jschoubben
19997d56c3
Not approved as drafted -- four things came out of checking them against each other, and one was a bug that would have broken every upgrade. The bug: 0059 specified Restart=on-failure while 0057 has the host restart onto a new binary by exiting CLEANLY. on-failure does not restart a process that exited zero, so every upgraded node would have been left stopped, having successfully upgraded. Found by reading the two records against each other rather than by either alone. Now Restart=always in all three places that mention it. The host cannot run in a container, and the reason is decisive rather than stylistic: step 0 of the substrate bootstrap installs the container runtime, so a host inside a container would need the thing it exists to install. It would also break 0041 -- copy it onto a machine and run it stops being true when the machine must already have a runtime. Everything above tier 0 is a container; the host is not. That split is the tier boundary, not an inconsistency. systemd is named rather than abstracted. An init is not a dependency in 0041's sense: 0041 is about what must be installed before the host works, and an init is not installed, it is what the machine already is. The unit file is the only systemd-specific artefact and it belongs to the package, so a machine with a different supervisor ships a different package. The mesh is a watchdog, and my first draft was half an answer. Recovery must be local -- nothing dials a node, and a host that cannot start cannot report. But detection is the mesh's, and a local supervisor structurally cannot do it: it sees one process failing and cannot tell a broken machine from a broken release. Only something watching every node can, and that distinction decides whether the response is "fix this machine" or "stop shipping this version". So a host rollout is staged -- a few nodes, wait for heartbeats, continue or stop on silence. Local rollback still needed, because the canary nodes break and because a node offline during the rollout gets the declaration later with no batch around it. The first declaration is the overlay and nothing else. Forced, because a node's address and peers are assigned rather than chosen. But also the way back in: a node reachable over the overlay can be fixed by hand if a later declaration breaks it, and a large first declaration risks a node that is broken and unreachable at once. Also stated plainly, because it reads as a contradiction: nodes reach each other over the overlay and every node consumes from the broker; what 0039 forbids is an inbound CONTROL surface, not reachability. And in 06: no node holds a credential to any control-plane store, for reads or writes. Four ADRs already say this separately and none of them said it in one place. Nodes state over the broker; the owning context writes. With a note that most high-frequency writes are observability's, not the registry's -- routing logs into the registry would be the shared-schema mistake arriving through a door marked performance.
03-DESIGN / 01-to-be
The mesh being built toward. Every statement here traces to a record in
02-DECISIONS/; nothing arrives by drafting.
A document here describes an intention. What currently runs is in
00-as-is/, and the two are never merged — when something ships, the as-is
document is written and this one's status becomes implemented.
| Document | Covers | Rests on |
|---|---|---|
00-work-breakdown.md |
How the decomposition gets built, in what order, and where a human must look | ADR 0015 |
01-end-to-end-testing.md |
The lab: a real mesh a change can be run against before it reaches nodes | ADR 0016, 0029 |
02-scenario-declaration.md |
What a scenario declares — the underlay, and what to place on it | ADR 0031 |
03-scenario-lifecycle.md |
What happens to a scenario — raise, snapshot, restore, move, destroy | ADR 0032 |
04-lab-installation.md |
Getting the lab onto a clean machine, and why it verifies capability rather than installation | ADR 0008 |
05-the-node-host.md |
Tier 0 — the one thing installed by hand, and the only thing that changes a machine | ADR 0037 |
06-the-control-plane.md |
Tier 2 — what the term means, and the test for what belongs in it | ADR 0037 |
07-the-substrate.md |
Tier 1 — what the control plane consumes and cannot grant itself | ADR 0038, 0048 |
08-connectivity.md |
One context in full — overlay, resolution, exposure, filtering, certificates | ADR 0049, 0050, 0051, 0055 |
09-the-node-lifecycle.md |
How a machine becomes a node, stays one, and stops being one | ADR 0038, 0051 |
Not yet written
- The remaining six contexts.
ADR 0055
settles the list at seven;
connectivityis the first written in full (08) and the other six do not exist yet. The work breakdown says in what order they are needed. Domain grouping outside the core.Not needed. ADR 0017 is superseded by ADR 0044: there is no domain module to group into, so there is no domain list to settle. Relationships are edges, and grouping is a tag and a query.