fix: export IMAGE_TAG in the remote deploy script -- guard could never pass - #6
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docker compose config --images runs as a separate child process, and a
compose file's \${IMAGE_TAG:-...} interpolation only sees variables that
are actually in that process's environment. IMAGE_TAG was a plain shell
assignment, not exported, so every docker compose invocation in the
remote script would silently fall back to the compose file's default
(<env>-latest) instead of the immutable per-commit tag -- meaning the
guard that verifies the pin would never match, and had it ever been
bypassed, an actual deploy would pull/run the wrong, mutable image
instead of the pinned commit.
Verified empirically: a minimal compose file with \${IMAGE_TAG:-x}
resolves to the default when IMAGE_TAG is a plain assignment in the
calling shell, and resolves correctly once exported. Caught by a
security-reviewer pass requested before editing the live VPS compose
file, ahead of any real cutover attempt.
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Summary
Found by a security-reviewer pass requested before editing the live VPS compose file (ahead of the actual cutover), not by code review alone -- this was caught empirically, not by inspection.
docker compose config --images(and the laterpull/up -d) run as separate child processes. A compose file's${IMAGE_TAG:-...}interpolation only sees variables actually present in that child process's environment.IMAGE_TAG="$2"in the remote deploy script was a plain shell assignment, never exported -- so everydocker composeinvocation would silently fall back to the compose file's default (<env>-latest) instead of the immutable per-commit tag. Practical effect: the guard that verifies the pin would never match (deploy always aborts, safely, but for the wrong stated reason), and if that guard were ever bypassed, a real deploy would pull/run the wrong, mutable image -- the opposite of what IMAGE_TAG-pinning exists for.Verified empirically: a minimal compose file with
${IMAGE_TAG:-x}resolves to the default when IMAGE_TAG is a plain assignment in the calling shell, and resolves correctly once exported (docker compose config --imagesoutput differs in each case). Fix:export IMAGE_TAG="$2".Test plan
ghcr.io/soy-chrislo/queres:staging-sha-<hash>and passescode-reviewer+security-reviewerboth run on the actual diff -- traced DEPLOY_PATH/TMP_DIR to confirm neither has the same exposure (both are shell-only usages, no export needed), confirmed no unintended leak of IMAGE_TAG into the alpine or app containers, confirmed the export must survive through pull/up -d (un-exporting after the guard would just relocate the bug)