---
status: open
opened: 2026-08-30
located-in: [mesh-lab]
fixed-by:
amended-design:
---

# 012 — A scenario machine cannot hold four images and raise a substrate

## Symptom

Adding a fourth image to the two-machine scenario made the bootstrap fail every time. The store
container was created, and its readiness check then failed for the full three minutes with
**no output at all**:

```
failed store-ready (in mesh-store: ... pg_isready ... exit 1):
  the action ran without error and its own verify still fails: docker exited 1:
```

Empty after the colon. The check runs `pg_isready` inside the container and prints the store's own
last lines when it gives up; producing nothing means **the container was not running**, which is a
different fault from a database that is slow to start.

Three images: the scenario raises, both machines join, and nine assertions pass. Four: it never
gets past the store. Reverting the fourth image restores it.

## What was tried

- **More memory.** Scenario machines were raised from 1 GiB to 2 GiB, on the reasoning that a
  machine running a database, a broker and the control plane at once is genuinely small. It did not
  change the outcome, so memory is not it — the change is kept because the reasoning holds
  independently.
- **A better diagnostic.** The readiness check now prints what it saw before giving up
  ([04-ISSUES/011](../011-one-broken-module-blocks-every-other/00-report.md) changed the apply
  around it). That is what showed the output was empty, which is what rules out slowness.

## What is most likely, and untested

**Disk.** Four images plus the base image on a machine whose root disk the scenario does not size.
A database that cannot write its data directory does not start, and the container exits — which
matches the evidence exactly. Nothing has measured it.

## What this blocks

The mesh running its **own artifact store** — a registry as a module — needs a registry image on
the machine so the module can mirror one, which is the fourth image. The module is written and its
manifest is accepted; what has not been proven is a machine assigned it serving artifacts to
another machine.

## How this will be checked

A scenario raised with four images comes up and passes the assertions that three do. Until then the
artifact-store test is not in the shared scenario, with a note saying where it went and why.