issue 130: undeclaring a service stops it, even one the mesh only reloads or keeps running #142

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jschoubben merged 5 commits from issue/130-undeclaring-a-service-stops-it into main 2026-09-26 22:58:43 +00:00
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@@ -7,7 +7,7 @@ reconstructed: false
extends: 0102-the-mesh-writes-into-a-shared-file-never-over-it.md
---
# 118. Undeclaring removes what the mesh made, gives back what it changed, and leaves the machine's units as they are
# 118. Undeclaring removes what the mesh made, and gives a unit back the state it was found in
## Context
@@ -57,34 +57,53 @@ keeps the dangerous behaviour as the default for exactly the units that matter m
runtime, the ssh daemon, the network — and each new module is one forgotten field away from a
machine that goes dark when it is unassigned.
**3. The line is ownership.** Chosen.
**3. Never stop a unit the mesh did not create.** Rejected, found while implementing it. The
mesh's packet filter is a unit the distribution installed and the mesh started at converge;
returning a node to adopted ([ADR 0100](0100-a-node-in-use-is-adopted-before-it-is-converged.md))
unloads it by undeclaring it. Never stopping it would leave the mesh's filter loaded beside the
predecessor's firewall re-enabled — the one rollback a converge promises, broken. Who wrote the
unit file is not the line; what the mesh *did* to the unit is.
**4. Give the unit back the state it was found in.** Chosen.
## Decision
**Undeclaring removes what the mesh made, gives back what it changed, and leaves what was the
machine's as it is.** For a unit, that means: **the host never stops, starts, disables or
enables a unit it did not create when that unit stops being declared.** An undeclared `service`
is forgotten — reported as such — and the unit keeps whatever state it is in.
**Undeclaring removes what the mesh made and gives back what it changed.** For a unit the mesh
did not create, what it changed is the unit's state, so that is what is given back: **the host
records the state it first found the unit in, and undeclaring returns the unit to it.**
- A unit the mesh *did* create — a `process` resource's unit, which the host writes — is still
stopped and removed with it. That is the mesh's own code.
- **Recorded once**, the first time the host applies the service — whether it was running, and,
where the declaration sets it, whether it was enabled at boot — and carried in the host's
record from then on. Later applies never overwrite it: by then the unit's state is the mesh's
doing.
- **A unit found running is left running.** The container runtime, the ssh daemon, a network
manager: running before the mesh arrived, running after it leaves.
- **A unit the mesh started is stopped again**, and one it enabled is disabled again — the packet
filter a converge loaded, which returning to adopted unloads.
- **Never started on the way out.** A unit the mesh stopped is not started again when its
declaration goes; starting something is a decision, and the operator makes it.
- **Unknown is left alone.** A record written before the host kept what it found says nothing
about the unit before the mesh; the unit is left exactly as it is. A unit left running can be
stopped by the operator; one stopped by mistake may be the link the operator needed to do it.
- A unit the mesh *did* create — a `process` resource's unit and bundle — is stopped and removed
with its declaration. That is the mesh's own code. (Before this record there was no way to
remove one at all: an undeclared process failed every apply on its node.)
- The service's settings the mesh wrote are given back by their own resources (a kept original
restored, a region or keys removed). A running service keeps running on what it read until it
next reads its configuration; the mesh does not restart it to make it notice.
- A service declared with no `state` (ADR 0117) remains the way to say the mesh must not
**start** a unit either; this record is about what happens when a declaration goes away, and
covers every service.
- An operator who wants a unit stopped when its module goes says so first: declare it
`stopped`, push, then unassign. Stopping a machine's unit is a decision, made visibly — never
a side effect of removing a module.
**start** a unit either; undeclared, it is forgotten.
## Consequences
- Unassigning the private network no longer stops the container runtime; unassigning sshd no
longer stops ssh; no uplink module can take a machine's network down on its way out.
- The host's removal report says "forgotten; the unit is the machine's" where it used to say
"stopped". A module that relied on its daemon stopping when unassigned — none in the catalogue
today does on purpose — needs the explicit step above.
- The host's removal report says what it gave back — "restored: stopped again, as the host
found it" — or "forgotten: it was running before the mesh; left as it is" where it used to say
"stopped". Its plan names each unit an undeclare will stop, before it does.
- On a fresh machine where the mesh installed and started a service, unassigning its module
stops it again — the mesh gave, the mesh takes back. An operator who wants it kept declares it
in a module of their own, or starts it themselves after.
- A daemon can keep running after its module is gone, on configuration that was taken back from
under it. That is a visible, running process the operator can see and stop; the alternative
was an invisible outage.
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@@ -200,7 +200,7 @@ python3 00-META/checks/index.py fail if stale
- **0114** — [A credential two parties hold rotates over two credentials; one a single party holds rotates in place, staged; and retiring a credential never removes what it reached](0114-a-shared-credential-rotates-over-two-credentials.md) *(proposed)*
- **0115** — [One assignment of a module per node: the module's name is the assignment's identity](0115-one-assignment-of-a-module-per-node.md) *(proposed)*
- **0117** — [A machine's uplink is a seat: the mesh configures the manager, never the link](0117-a-machines-uplink-is-a-seat.md)
- **0118** — [Undeclaring removes what the mesh made, gives back what it changed, and leaves the machine's units as they are](0118-undeclaring-leaves-the-machines-units-running.md)
- **0118** — [Undeclaring removes what the mesh made, and gives a unit back the state it was found in](0118-undeclaring-gives-a-unit-back-the-state-it-was-found-in.md)
### How it is built
@@ -2,7 +2,7 @@
status: located
opened: 2026-09-27
located-in: [mesh-host internal/apply/apply.go (remove)]
amended-design: 02-DECISIONS/0118-undeclaring-leaves-the-machines-units-running.md
amended-design: 02-DECISIONS/0118-undeclaring-gives-a-unit-back-the-state-it-was-found-in.md
---
# 130 — undeclaring a service stops it, even one the mesh only reloads or only keeps running
@@ -45,10 +45,22 @@ reaches it by.
## Resolution
[ADR 0118](../../02-DECISIONS/0118-undeclaring-leaves-the-machines-units-running.md): undeclaring
removes what the mesh made, gives back what it changed, and leaves the machine's units as they
are. An undeclared `service` is forgotten, never stopped — the host did not create the unit.
That covers the runtime, sshd and the uplink modules at once, without each module opting out;
the private network and the sshd module need no change. A `process`'s unit, which the host does
write, is still stopped and removed. The unassign preview asked for above is left open for the
controller.
[ADR 0118](../../02-DECISIONS/0118-undeclaring-gives-a-unit-back-the-state-it-was-found-in.md):
undeclaring removes what the mesh made and gives back what it changed. The host records the state
it first found a unit in, and undeclaring returns the unit to it — a unit found running (the
container runtime, sshd, a network manager) is left running; one the mesh started (the packet
filter a converge loaded) is stopped again; nothing is started on the way out; a record from
before the host kept what it found leaves the unit alone. That covers the runtime, sshd and the
uplink modules at once, without each module opting out; the private network and the sshd module
need no change.
A first draft — never stop a unit the mesh did not create — was rejected while implementing it:
returning a converged node to adopted unloads the mesh's filter by exactly this path.
Found on the way: an undeclared `process` failed every apply on its node (`remove` had no case
for it). Now removed with its unit, timer and bundle — the mesh's own code. `user` and `archive`
have the same gap and are left for their own decisions: removing a login or unpacked files is not
something to settle in passing.
The unassign preview is partly answered — the host's plan names each unit it will stop — and the
controller's side is left open.