64 lines
3.1 KiB
Markdown
64 lines
3.1 KiB
Markdown
---
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status: open
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opened: 2026-10-03
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located-in:
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- mesh-controller
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- mesh-catalog
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fixed-by:
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amended-design:
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---
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# 213 — The controller is a Go program, and it still runs in a container
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## What was observed
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2026-10-03. The controller — the program that holds the `mesh-controller` seat and answers its
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verbs (`status`, `nodes`, `push`, `assign` …), composes every machine's declaration and plans the
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builds — runs on its machine as a container built from an image:
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```
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mesh-controller Up … (docker ps on the machine that runs it)
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```
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It is written in Go and compiles to one static binary, as the node host does. The host is delivered
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as a bundle and run as a process; the node's tool runtime now is too
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([ADR 0193](../../02-DECISIONS/0193-every-bundle-the-runtime-serves-is-launched-and-the-runtime-knows-no-language.md)).
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The controller is the one piece of the mesh's own Go code still shipped as an image.
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## Why it matters beyond this instance
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[ADR 0188](../../02-DECISIONS/0188-a-modules-own-code-is-bundles-in-any-language-and-a-tools-bundle-speaks-mcp-to-the-runtime.md)
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§1 says a module's own code is bundles, never an image, and §3 that a bundle that is a service is a
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`process` the host runs. The controller breaks the rule it is the mechanism of: the registration
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gate that will refuse an image of a module's own code has to exempt the controller, or refuse it.
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It also costs what an image costs — a container runtime on its machine as a hard requirement,
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eight mounts standing in for files a process would simply read, an image rebuild for a binary
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change — and
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every restart of it is a container recreation, which is how the controller restarts in the middle
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of a plan today.
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## What a fix has to settle
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- The controller's module declares a Go bundle (`system`, `binary`) and a `process` running it
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(`./<binary>`, mesh-host #81), with its credential and store connection as files and words, not
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container mounts and a container network name.
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- What the container gives it now that a process would not: it runs on the host's network already,
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as an unprivileged user (65534), with eight mounts. Each mount named and replaced by a path, and
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the user by an account the host declares.
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- The handover: the controller restarting itself as a process, on the one machine that runs it,
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without a window where nothing answers the mesh's verbs.
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Located only by owner; the move is a change of the controller's module and its deployment, not of
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its code.
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## Fix prepared (2026-10-04)
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Three changes. mesh-host#86, merged: a process may name the container it `replaces`, and the host
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removes that container only once the process has stayed up across two checks. mesh-controller#252,
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awaiting the operator's merge: the controller's composition for a service process, and two
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controllers safe together for the handover — the second stands by on the controller's consumers
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until the first lets go, and all plan work holds one advisory lock. mesh-controller#253, held: the
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controller's manifest as a Go bundle and a process. It waits on
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[issue 223](../223-a-new-mesh-installs-its-controller-as-a-container/00-report.md), because with it a
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new mesh cannot be installed.
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