jschoubben
77f3a4cea7
Every remaining cluster merged. Each was one design that had been split across
several records because it was worked out over days rather than at once.
the node host 8 -> 1 applies not decides, depends on nothing,
per operating system, root service, the
launcher, episodic, what a declaration is,
actions from the bundle only
a node and how it joins 4 -> 1 what a node is, joining, the link as
security boundary, the enrolment token
modules and the graph 7 -> 1 everything is a module, no domain modules,
three edges, provisioning, the core library
substrate and control 6 -> 1 the test, seven contexts, one control plane,
plane the authority is not a database, the named
products, the pinned bundle
connectivity 3 -> 1 a route is a grant, reachability declared,
filter rules
delivery 5 -> 1 reconciliation not a pipeline, artifacts,
the three silos, a failed step, the verdict
the lab 5 -> 1 (earlier)
how this repository 10 -> 1 (earlier)
works
Nothing was dropped. Each consolidated record carries the reasoning of the ones
it absorbs -- the measurements, the incidents, the alternatives rejected --
because that reasoning is the only reason to keep a record at all. What is gone
is the fragmentation: eight files to read to understand tier 0, when tier 0 is
one component.
The four superseded records went too. They existed to point at their
successors, and the successors now contain what they said.
The checker made this safe. Each merge left dangling links -- 38 files after
the host merge alone -- and it named every one. Nothing was found by reading,
and a manual pass would certainly have missed some, including references inside
AGENTS.md which every session loads.
81 lines
4.1 KiB
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81 lines
4.1 KiB
Markdown
---
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status: graduated
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initiated: 2026-08-22
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touches: [03-DESIGN/00-as-is/05-runtime-and-installation.md]
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became:
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- 02-DECISIONS/0037-the-node-host.md
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- 02-DECISIONS/0037-the-node-host.md
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- 03-DESIGN/01-to-be/05-the-node-host.md
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---
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# 003 — Who supervises a service
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**No longer blocks Phase 0** (see below).
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- **Initiated by:** jochen, 2026-08-22, in response to
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[`002-local-mesh`](../002-local-mesh/analysis.md) open question 1
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- **Areas touched:** every module shipping a `systemd/` directory (14), the
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`hal-module@` template, `hal/sdk` feature handlers, `dev_up`, `log_tail` /
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`systemd_journal`, the bootstrap scripts.
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## The question
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`002` asked how a containerised node runs a module service, given that a module service is
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defined today as a systemd unit running `docker compose` against `/services/`. The response
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was the better question:
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> If it's possible to run systemd inside a container, that's the way to go I think. However,
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> what would the cost be to step away from systemd to run our services and set it up in a
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> different way? More hal mesh approach.
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This effort answers the cost half. It does not choose.
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## Summary of findings
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- **The question splits in two**, and the halves have opposite answers. Supervising
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`docker compose` stacks through systemd is largely **redundant** — 44 of 44 module compose
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files already declare a restart policy, so Docker is already the supervisor. Supervising
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HAL's **9 long-running Node daemons** is not redundant: `Restart=always` is currently the
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only thing between a crash and a dead node.
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- **The hard part is fate-sharing, not systemd.** meshware already cannot restart itself and
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carries a documented workaround for it. Any mesh-native supervisor inherits that problem
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recursively unless it sits outside the mesh's own process tree — at which point it is an
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OS-level supervisor again, just reinvented.
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- **There is a third option neither of us named**, and it is the one that also solves Phase 0:
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run HAL's own daemons as containers, making Docker the supervisor for everything. Local and
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production then have the same shape rather than a translation layer between them.
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- **It cannot be all-or-nothing**, and ADR 0015 already says why: a human agent acts through a
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shell and a desktop. Those parts are on the host by definition.
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- One incidental finding: the automatic node rescue that documentation describes **does not
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exist**. No unit declares `OnFailure=`, and nothing calls `hal-rescue.sh` on a timer.
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Detail and costs in [`analysis.md`](analysis.md).
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## What it became
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*Closed 2026-08-28.* The decision this effort asked for was taken — and taken without citing it,
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which is why the effort sat `active` for five days after being answered. Recorded here because
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finding that is the point of a sweep.
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**The third option is what the mesh adopted.** `Docker is the supervisor for everything` is
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[ADR 0037](../../02-DECISIONS/0037-the-node-host.md): the
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host is a plain process on the machine and everything above tier 0 is a container. The substrate
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bootstrap declares no service at all — it is package, container, action, container — so the
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44-of-44 restart policies this effort counted are the supervision, exactly as it argued.
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**Fate-sharing was the hard part, and it is solved the way this effort predicted.** It said any
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mesh-native supervisor inherits the problem *unless it sits outside the mesh's own process
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tree*. [ADR 0037](../../02-DECISIONS/0037-the-node-host.md) puts
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the launcher there: it supervises the host as a child and shares no code with it, so a host that
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cannot start is still recovered.
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**It is not all-or-nothing, as this effort insisted.** A human agent acts through a shell and a
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desktop, and those are on the host. So is the host itself — the one thing an init starts.
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## What is not closed
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**The automatic node rescue the documentation describes does not exist.** No unit declares
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`OnFailure=`, and nothing calls the rescue script on a timer. That is a documented behaviour
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which never happens, and it outlives this effort — filed as
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[`04-ISSUES/008`](../../04-ISSUES/008-the-documented-node-rescue-does-not-exist/00-report.md)
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rather than closed with it.
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