issue 121: a volume path is not in the spec comparison, and a roll-out raced a data move

2026-09-26 17:07:51 +02:00
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+---
+status: open
+opened: 2026-09-26
+located-in: [mesh-host internal/apply]
+---
+
+# 121 — a volume path is not in the spec comparison, and a roll-out raced a data move
+
+## What was observed
+
+Landing the "module data lives in /var/lib" change on novox (mesh-catalog #97), two
+distinct faults surfaced in one hour:
+
+1. **Building a module with a roll-out upgrade policy IS deploying it.** gitea's policy
+   was roll-out; the `build` that registered its repathed manifest sent it to the node
+   immediately, which recreated the container mounting the *not-yet-renamed* (empty)
+   `/var/lib/gitea/data`. The forge came back as its own install page, fresh host keys
+   and all, and every subsequent pipeline build died on `repository not found` — which
+   also blocked the fix, since re-registering the other modules needed the forge. The
+   operator narrative "build, then move data, then push" is only safe under the record
+   policy; nothing warned that one module in the batch would skip the pause.
+
+2. **Changing a container's volume paths does not recreate the container.** After the
+   final push, five of the six repathed modules kept their old containers running
+   ("Up 13–26 hours") — the new declaration's volume paths differ from the running
+   containers' mounts, and the apply judged them current. Same class as mesh-host #27
+   (`dns`/`ip` absent from the comparison): a field the comparison does not read is a
+   field that can never change a running container. Benign here only because a rename
+   on one filesystem preserves the mounted inode — the running containers keep serving
+   the same bytes the new path names, and the next natural recreation converges. A
+   cross-filesystem move, or a path change to *different* data, would have silently
+   split the module between two worlds.
+
+## What would have prevented it
+
+- `build` printing the module's upgrade policy when that policy will act on the result
+  ("gitea rolls out on build — the node will receive this immediately"), or a
+  `--register-only` flag for exactly this choreography.
+- Volumes (and every other container field) in the spec comparison, or the honest
+  refusal: "this field changed and I cannot apply it without recreation."
+
+## Recovery that worked
+
+Instant renames both ways broke the circular dependency (forge needed for builds,
+builds needed for the push, push needed for the forge): data back to the old path,
+old-spec forge started, artifacts rebuilt, data renamed forward, push. Nothing lost;
+the install-page junk was discarded twice.