Issues 094 and 095, both found in the first module's cutover #83
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---
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status: located
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opened: 2026-09-23
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located-in: [mesh-controller internal/catalogue/filtering.go, mesh-controller cmd/mesh-controller/plan.go]
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fixed-by:
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amended-design:
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---
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# 094 — A port published as the machine side of a mapping cannot be moved, and trying blocks every push
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## What was observed
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On the control-node, immediately after the first module was migrated, 2026-09-23.
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A module publishes two ports. One is written short, so the machine's side and the software's side
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are the same number. The other is written long: **a machine port mapped to a different port inside
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the container**, because the software's own port is one the machine's own daemon already holds.
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The module's `listens` names the **machine** side of that mapping, deliberately, and says why.
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The predecessor served that port on a different machine port. Moving the module's to match — the
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whole point of a port being a per-node setting
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([ADR 0100](../../02-DECISIONS/0100-a-node-in-use-is-adopted-before-it-is-converged.md)) — was
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refused:
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```
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gives port 2222 a machine port, and no container of its publishes 2222 —
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the mesh cannot move a port the module does not publish
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```
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It does publish it. The check collects only the **last** segment of each published entry, which is
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the container's inner port, so for a long-form mapping it sees the wrong half. Naming the inner
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port instead is accepted and then never consulted, because the lookup is by what the module says
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it listens on — which is the machine side.
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**And the refusal is not confined to the setting.** While that setting exists, composition fails,
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so **every push to that node is refused** until it is removed. A setting that cannot work should
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be refused where it is set, not where it is read.
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The same blind spot appears one step further on: on an adopted node **no opening was derived** for
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that port either, and a per-node `expose` for it produced none, so the firewall never opened what
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the module serves.
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## Why it matters beyond this instance
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Every module that maps a machine port to a different port inside its container has this hole, and
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the pattern is common precisely where it matters: a service whose own port collides with something
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the machine already runs. It is also exactly the case a migration hits, because matching the
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predecessor's port is how a service keeps working when it changes hands.
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The push-blocking half is worse than the feature gap. One unusable setting stops a machine being
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told anything at all, and the message names a port rather than the setting that caused it.
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## Open questions
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- Should a setting name the port the software listens on, the machine port, or either, and what
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refuses the ambiguous case where a module publishes both halves of some other mapping?
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- Should `settings set` validate against the module's manifest at the moment it is set, so an
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impossible setting cannot be stored?
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- Should composition fail the whole node, or fail that module and send the rest?
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@@ -0,0 +1,47 @@
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---
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status: located
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opened: 2026-09-23
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located-in: [mesh-controller cmd/mesh-controller/modules.go]
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fixed-by:
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amended-design:
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---
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# 095 — A module assigned after genesis has no broker account, and finds out by restarting
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## What was observed
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On the control-node, during the first migration, 2026-09-23.
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A module was assigned and taken. Its service came up and served correctly. Its **sidecar** — the
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part that speaks on the bus — restarted every few seconds with:
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```
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cannot read the broker credential at /run/secrets/broker: SyntaxError: Unexpected token 'V',
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"VK-XiWBjPt"... is not valid JSON
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```
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The module declares an own-secret named `broker`, as every module on the bus does. The mesh had
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minted it as **a random value**, the way it mints any own-secret, where the sidecar expects an
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**account**: a url with credentials in it.
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The account is a separate, explicit act — `module issue <module> --node <machine>` — which genesis
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performs for the foundation's own modules. Nothing performs it for a module assigned afterwards,
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and nothing says it is needed. Running it delivered a real account and the sidecar came up.
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## Why it matters beyond this instance
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Every module with a sidecar will be assigned after genesis, because that is what migrating a
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service is. The failure is late, and it looks like a code fault in the module rather than a
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missing step: the service works, and only the half that talks to the mesh crashes.
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Two mechanisms share one name here. `own-secrets: {broker: …}` means *give me a place to put my
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broker credential*, and the minting path treats it as *mint me a secret called broker*. Nothing
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reconciles them.
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## Open questions
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- Should assigning a module that declares a `broker` own-secret issue its account, rather than
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leaving a minted value that cannot work?
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- Or should the minting path refuse that name, so the missing act is named at once instead of
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discovered by a crash loop?
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- What else declares an own-secret whose name means something to another part of the mesh?
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