jschoubben
2204b01909
The host was described as a component and never as something that runs for years on a machine somebody else also uses. 09 covers every state a machine can be in and every transition between them. Four states: unmanaged, hosted, enrolled, disconnected. Only the last two are nodes, and they are the same node in two situations. `hosted` -- the host installed but never told which mesh it belongs to -- had no name before and is where a machine sits between the two adoption commands. Things that were unclear and now are not: The first node walks the same path in an unusual order: reconcile from the bundle, the control plane it just raised issues a token, enrol against it. Its specialness lasts two commands. A side effect worth having -- enrolment is exercised on node one, rather than being written and first used on node two. Enrolment reports profile and inventory BEFORE the control plane decides anything. The profile is the input to that decision, not a diagnostic; the control plane cannot decide what a machine should run without knowing what it can run. Rebooting mid-apply is safe by construction. The store records each resource after it worked, so a host that dies half way through comes back and applies the rest. The rule that stops the host lying about what it did also makes it crash-safe. Retiring splits in two. Graceful is a final empty declaration. A node that is gone will reconcile its last declaration forever -- the honest consequence of making disconnection ordinary. The answer is not to make the host expire but that the node holds nothing that outlives revocation: every grant is a per-node credential revoked at the provider. A lost node keeps running and stops being able to reach anything. Said plainly rather than implying the mesh can switch a machine off, which it cannot and should not. Losing the store is quiet and permanent, so it gets its own section. The host re-enrols and re-applies fine; what does not come back is removal, because resources it no longer has a record of become unowned and sit there indefinitely. Also corrects 0057, which said the mesh must not upgrade the host at all. That conflated two acts. Replacing the binary is safe -- Unix keeps the running inode. Stopping the unit is not. So the host may apply a package naming itself, and restarts by finishing its apply and exiting cleanly, letting the supervisor start it on the new binary. It never asks the service manager to restart it. That makes a fleet-wide host upgrade an ordinary declaration, which the first draft gave up on. 0057 remains proposed.
35 lines
3.6 KiB
Markdown
35 lines
3.6 KiB
Markdown
# 03-DESIGN / 01-to-be
|
|
|
|
The mesh being built toward. Every statement here traces to a record in
|
|
[`02-DECISIONS/`](../../02-DECISIONS/); nothing arrives by drafting.
|
|
|
|
A document here describes an intention. What currently runs is in
|
|
[`00-as-is/`](../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`](00-work-breakdown.md) | How the decomposition gets built, in what order, and where a human must look | [ADR 0015](../../02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md) |
|
|
| [`01-end-to-end-testing.md`](01-end-to-end-testing.md) | The lab: a real mesh a change can be run against before it reaches nodes | [ADR 0016](../../02-DECISIONS/0016-a-lab-node-is-a-virtual-machine.md), [0029](../../02-DECISIONS/0029-the-labs-first-scenario-has-no-pipeline.md) |
|
|
| [`02-scenario-declaration.md`](02-scenario-declaration.md) | What a scenario declares — the underlay, and what to place on it | [ADR 0031](../../02-DECISIONS/0031-the-lab-provides-the-underlay.md) |
|
|
| [`03-scenario-lifecycle.md`](03-scenario-lifecycle.md) | What happens to a scenario — raise, snapshot, restore, move, destroy | [ADR 0032](../../02-DECISIONS/0032-a-scenario-is-an-isolated-address-space.md) |
|
|
| [`04-lab-installation.md`](04-lab-installation.md) | Getting the lab onto a clean machine, and why it verifies capability rather than installation | [ADR 0008](../../02-DECISIONS/0008-a-failed-step-fails-the-job.md) |
|
|
| [`05-the-node-host.md`](05-the-node-host.md) | Tier 0 — the one thing installed by hand, and the only thing that changes a machine | [ADR 0037](../../02-DECISIONS/0037-the-host-applies-it-does-not-decide.md) |
|
|
| [`06-the-control-plane.md`](06-the-control-plane.md) | Tier 2 — what the term means, and the test for what belongs in it | [ADR 0037](../../02-DECISIONS/0037-the-host-applies-it-does-not-decide.md) |
|
|
| [`07-the-substrate.md`](07-the-substrate.md) | Tier 1 — what the control plane consumes and cannot grant itself | [ADR 0038](../../02-DECISIONS/0038-a-node-joins-by-linking-first.md), [0048](../../02-DECISIONS/0048-the-substrate-is-named.md) |
|
|
| [`08-connectivity.md`](08-connectivity.md) | One context in full — overlay, resolution, exposure, filtering, certificates | [ADR 0049](../../02-DECISIONS/0049-a-route-is-a-grant.md), [0050](../../02-DECISIONS/0050-reachability-is-a-property-of-the-address.md), [0051](../../02-DECISIONS/0051-the-enrolment-token-carries-the-mesh.md), [0055](../../02-DECISIONS/0055-the-control-plane-is-the-node-coordinating-contexts.md) |
|
|
| [`09-the-node-lifecycle.md`](09-the-node-lifecycle.md) | How a machine becomes a node, stays one, and stops being one | [ADR 0038](../../02-DECISIONS/0038-a-node-joins-by-linking-first.md), [0051](../../02-DECISIONS/0051-the-enrolment-token-carries-the-mesh.md) |
|
|
|
|
## Not yet written
|
|
|
|
- **The remaining six contexts.**
|
|
[ADR 0055](../../02-DECISIONS/0055-the-control-plane-is-the-node-coordinating-contexts.md)
|
|
settles the list at seven; `connectivity` is the first written in full
|
|
([`08`](08-connectivity.md)) 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](../../02-DECISIONS/0017-modules-outside-the-core-are-grouped-by-domain.md) is
|
|
superseded by [ADR 0044](../../02-DECISIONS/0044-a-module-declares-presence-instantiation-and-exclusion.md):
|
|
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.
|