fix(mosaico): fail fast when mktemp cannot create the scratch dir

[ofir-frd]

Follow-up to #2556, from a Qodo finding that landed after it merged.

docker/mosaico/smoke_test.sh runs under set -uo pipefail without -e, so a failed mktemp -d left TMPDIR_RUN empty and execution continued. Every subsequent write then targeted the filesystem root:

$ TMPDIR_RUN="$(mktemp -d /nonexistent/tmp.XXXX 2>/dev/null)"
$ echo "$TMPDIR_RUN/health.json"
/health.json

Guard the assignment so the script exits instead.

Verified: guard fires and exits 1 when mktemp fails; ./smoke_test.sh against the pinned image still reports FULL ROUND-TRIP PASSED.

[qodo-free-for-open-source-projects]

PR Summary by Qodo

Fail fast in mosaico smoke test when mktemp scratch dir creation fails

🐞 Bug fix 🕐 Less than 10 minutes

AI Description

• Abort smoke test immediately if mktemp -d fails to create a scratch directory.
• Prevent accidental writes to filesystem root when TMPDIR_RUN is empty.

Diagram

graph TD
A["smoke_test.sh"] --> B{"mktemp -d ok?"} --> C["TMPDIR_RUN set"] --> D["write health.json"] --> E[("filesystem")]
B --> F["exit 1 (stderr)"]
subgraph Legend
direction LR
_script["Script"] ~~~ _dec{"Decision"} ~~~ _fs[("Filesystem")]
end

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High-Level Assessment

The following are alternative approaches to this PR:

1. Enable `set -e` (errexit) for the script

• ➕ Automatically fails on many command errors without per-command guards
• ➕ Reduces risk of similar unchecked failures elsewhere
• ➖ Can be behavior-changing for intentionally handled failures (requires careful audit)
• ➖ May necessitate refactors (e.g., cmd || true, conditional checks) to preserve current control flow

2. Validate `TMPDIR_RUN` after assignment (non-empty + directory exists)

• ➕ Directly asserts the invariant the rest of the script depends on
• ➕ More robust if mktemp returns an unexpected value
• ➖ Slightly more verbose than guarding mktemp directly
• ➖ Still requires remembering to add checks for other critical variables

Recommendation: Keep the current approach: guard the mktemp -d assignment and exit with a clear error. It’s minimally invasive, preserves the existing set -uo pipefail behavior, and directly prevents the dangerous empty-variable path that could redirect writes to /.

Files changed (1) +1 / -1

Bug fix (1) +1 / -1

smoke_test.shAdd fail-fast guard for mktemp scratch directory creation +1/-1

Add fail-fast guard for mktemp scratch directory creation

• Wraps 'mktemp -d' with an explicit error path that prints a failure message to stderr and exits non-zero. Prevents subsequent commands from using an empty 'TMPDIR_RUN' and writing artifacts to the filesystem root.

docker/mosaico/smoke_test.sh

[qodo-free-for-open-source-projects]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

Great, no issues found!

Qodo reviewed your code and found no material issues that require review

• Author self-review: I have reviewed the code review findings, and addressed the relevant ones.