jschoubben
e1febe8e0f
The consolidation left a sparse sequence -- 1, 4, 6, 7, 9, 10, 12, 15, 16, 18, 19, 25, 34, 35, 36, 37, 40, 42, 44, 45, 48, 49, 58 -- where the gaps were only the archaeology of what used to be there. Renumbered contiguously. Renames run in ascending order, so every target number is already free and no two files ever collide. The reference rewrite is one simultaneous pass rather than a sequence of replacements. Numbers moved into slots other numbers were vacating -- the node host went 37 to 16 while the lab went 16 to 9 -- so replacing one at a time would have cascaded and silently pointed things at the wrong record. Seven plain-text references survived the merges as prose rather than links, naming records that no longer existed: the enrolment token, the link boundary, what a declaration is, reachability, the repository structure. Each mapped to the consolidated record that now holds it. Verified rather than assumed: every [ADR NNNN](path) link now has matching text and target, checked across the whole repository, and the checker passes. Frontmatter `consolidates:` lists dropped -- they named records that are gone, and each consolidated record already says in prose what it absorbed.
87 lines
3.8 KiB
Markdown
87 lines
3.8 KiB
Markdown
---
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layer: as-is
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status: implemented
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code: [hal]
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updated: 2026-08-23
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decisions:
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- 02-DECISIONS/0002-managed-files-are-generated-never-edited.md
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- 02-DECISIONS/0019-modules-and-the-graph.md
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---
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# Configuration and secrets
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Every value a module reads at runtime comes from a file on a node's disk. Every one of those
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files is **generated**.
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## The rule
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A managed file is derived from the mesh database. A synchroniser rewrites it when the values
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behind it change. The write path is the mesh operation that owns the value; the file is an
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output ([ADR 0002](../../02-DECISIONS/0002-managed-files-are-generated-never-edited.md)).
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An edit to a managed file survives until the next synchronisation and is then overwritten
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silently, taking whatever it was fixing with it — bringing back the bug the edit had removed,
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with a delay, and with no error to connect the two events.
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There is a way to ask whether a given file is managed. That question has to be asked, because
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the answer is not visible from the file.
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## What is managed
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Generated environment files for each module, service definitions in each module's runtime
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directory, managed configuration files a module declares, and node-level settings. The list is
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not a category — it is whatever a synchroniser claims, which is why the question is asked of
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the tooling rather than answered from a rule.
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## How a value is decided
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Values resolve by precedence, highest first:
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1. **A database override** — set deliberately, or written by a provisioner.
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2. **The value already in the generated file** — preserved for anything without an override.
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3. **A generated value** — a random secret, a template composed from other variables, or a
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value pulled from the node's own record.
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4. **The manifest default.**
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Two consequences follow, and both are subtle enough to have caused confusion.
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The second rule is what keeps a generated password **stable** across regenerations. It is not
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an oversight; without it every regeneration would issue a new secret and break whatever holds
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the old one.
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The same rule means that **changing a manifest's default does not change anything already
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using it**. The existing file's value wins. The new default reaches only installations that
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never had one.
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Removing a declaration is worse than changing it: the old override row and the file it produced
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are both left behind. Configuration is additive in practice, whatever the manifest says.
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## Secrets
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Generated secrets are produced by the mesh, never authored. Provisioned credentials arrive as
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database overrides written by the provisioner and are marked as such, so they can be
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distinguished from a deliberate override and cleaned up when the grant is removed
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([ADR 0019](../../02-DECISIONS/0019-modules-and-the-graph.md)).
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Nothing in the repository contains a credential. The repository has no per-node content at all,
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which is what makes that guarantee structural rather than a matter of care.
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Two known weaknesses, both recorded rather than resolved:
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**Generated environment files were world-readable.** The mode passed at write time only applies
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when the file is created, so regeneration left the previous mode in place. The class of bug is
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worth remembering beyond the instance: a permission set at creation is not a permission
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maintained.
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**Rotation is not a mesh operation.** Secrets can be generated and granted; there is no
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mechanism that rotates one and informs everything holding it. Where a rotation has been done,
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it has been done by hand, and doing it wrong has taken services down.
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## Node-level and mesh-level values
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A node-level value applies to everything on one node. A mesh-level value applies everywhere and
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is read by every node — the broker's location is the canonical example, and a wrong one is how
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a mesh fails to form.
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Neither is a file that anyone edits. Both are database records that produce files.
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