fix: make legacy multi-arch builds reliable

Author: seebeen

CLAUDE.md

@@ -72,5 +72,7 @@ for `linux/amd64`, `linux/386`, and `linux/arm/v5`.
 - Keep pinned APT installation before local `COPY` instructions.
 - Keep shell compatible with Debian Etch's Bash 3 and validate with `bash -n`.
 - Preserve Docker Official Image semantics where MySQL 5.0 supports them.
+- Treat QEMU execution of `linux/arm/v5` as best effort; Buildx output is
+  supported, but MySQL's legacy threaded bootstrap requires native validation.
 - Use non-interactive cleanup and never commit database dumps.
 - Run `make structure` and `make smoke` after runtime changes.

Dockerfile

@@ -3,13 +3,20 @@ FROM debian/eol:etch-slim
 
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Etch APT requires the configuration form of no-install-recommends.
+# Etch APT requires the configuration form of no-install-recommends. Divert
+# mysqld while dpkg runs its postinst: that script bootstraps a throwaway data
+# directory several times, which is both slow under emulation and deleted below.
 RUN printf '#!/bin/sh\nexit 101\n' > /usr/sbin/policy-rc.d \
     && chmod +x /usr/sbin/policy-rc.d \
+    && dpkg-divert --add --rename --divert /usr/sbin/mysqld.distrib /usr/sbin/mysqld \
+    && printf '#!/bin/sh\nexit 0\n' > /usr/sbin/mysqld \
+    && chmod +x /usr/sbin/mysqld \
     && apt-get update \
     && apt-get install -y -o APT::Install-Recommends=false \
         mysql-server-5.0=5.0.32-7etch12 \
         mysql-client-5.0=5.0.32-7etch12 \
+    && rm -f /usr/sbin/mysqld \
+    && dpkg-divert --rename --remove /usr/sbin/mysqld \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/* \
         /var/cache/apt/archives/*.deb \

README.md

@@ -43,7 +43,10 @@ The image index publishes these Etch-supported platforms:
 - `linux/arm/v5`
 
 There is no native `linux/arm64` image. An ARM64 host must explicitly request
-and emulate the 32-bit ARM image when its Docker/QEMU setup supports it:
+and emulate the 32-bit ARM image when its Docker/QEMU setup supports it.
+Buildx can build the artifact, but current user-mode QEMU may fail MySQL 5.0's
+threaded bootstrap with `Can't create interrupt-thread`; treat emulated runs as
+best effort and validate production use on native compatible ARM32 hardware.
 
 ```bash
 docker run --rm --platform=linux/arm/v5 \
@@ -167,14 +170,15 @@ make build       # Build linux/amd64 by default
 make build-all   # Build all release platforms into the Buildx cache
 make structure   # Verify package, config, and image cleanup
 make smoke       # Verify initialization, TCP auth, init files, and persistence
-make smoke-all   # Build and smoke all platforms under native/QEMU execution
+make smoke-all   # Attempt the lifecycle smoke test on every release platform
 make run         # Run the selected image locally
 make shell       # Open Bash in the selected image
 ```
 
 Override `PLATFORM`, `IMAGE`, `VERSION`, `ROOT_PASSWORD`, or `PORT` as needed.
 Multi-platform targets require a Buildx builder with the corresponding QEMU
-handlers.
+handlers. `make smoke-all` fails honestly when the host emulator cannot run an
+architecture's MySQL bootstrap; this is a known possibility for `arm/v5`.
 
 ## Releases
 

tests/smoke.sh

@@ -23,7 +23,7 @@ trap cleanup EXIT
 
 wait_for_mysql() {
     local attempt running
-    for attempt in $(seq 1 120); do
+    for attempt in $(seq 1 "${MYSQL_WAIT_ATTEMPTS:-120}"); do
         running="$(docker inspect --format '{{.State.Running}}' "$CONTAINER" 2>/dev/null || true)"
         if [ "$running" != true ]; then
             docker logs "$CONTAINER" >&2 || true
@@ -41,6 +41,7 @@ wait_for_mysql() {
 query_from_peer() {
     docker run --rm --platform="$PLATFORM" --network="$NETWORK" \
         --entrypoint mysql "$IMAGE" --protocol=TCP --host=db \
+        --connect-timeout="${MYSQL_CONNECT_TIMEOUT:-3}" \
         --user="$1" --password="$2" --batch --skip-column-names \
         --execute="$3"
 }