Dockerize: self-contained stack + B2 backup sidecar

backup/Dockerfile

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+# Tiny rclone + sqlite sidecar that backs up /data to Backblaze B2 on a loop.
+FROM alpine:3.20
+
+RUN apk add --no-cache rclone sqlite tzdata
+
+COPY backup.sh /backup.sh
+RUN chmod +x /backup.sh
+
+ENV BACKUP_INTERVAL=86400
+
+# Run once on boot, then every BACKUP_INTERVAL seconds. A failed run is logged
+# but does not kill the loop.
+CMD ["sh", "-c", "while true; do /backup.sh || echo '[backup] FAILED'; sleep \"${BACKUP_INTERVAL}\"; done"]

backup/backup.sh

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+#!/bin/sh
+# Snapshot the app's data to Backblaze B2 via rclone.
+#   - SQLite DB: a consistent .backup snapshot (safe while the app is running)
+#   - uploads:   mirrored to B2
+# rclone's B2 remote ("b2:") is configured entirely from RCLONE_CONFIG_B2_*
+# env vars (set in .env / compose). Runs once; the container loops it.
+set -eu
+
+STAMP=$(date +%Y%m%d-%H%M%S)
+DEST="b2:${B2_BUCKET}/moon-household-budget"
+KEEP_DAYS="${BACKUP_KEEP_DAYS:-30}"
+
+echo "[backup ${STAMP}] starting"
+
+# 1. SQLite snapshot (only if a db file is present)
+if [ -f /data/app.db ]; then
+  sqlite3 /data/app.db ".backup '/tmp/app-${STAMP}.db'"
+  rclone copyto "/tmp/app-${STAMP}.db" "${DEST}/db/app-${STAMP}.db"
+  rm -f "/tmp/app-${STAMP}.db"
+  echo "[backup ${STAMP}] db snapshot uploaded"
+else
+  echo "[backup ${STAMP}] no /data/app.db — skipping db snapshot"
+fi
+
+# 2. Uploaded images (and anything else under /data except the live db)
+if [ -d /data/uploads ]; then
+  rclone sync /data/uploads "${DEST}/uploads"
+  echo "[backup ${STAMP}] uploads synced"
+fi
+
+# 3. Prune old db snapshots
+rclone delete --min-age "${KEEP_DAYS}d" "${DEST}/db" 2>/dev/null || true
+
+echo "[backup ${STAMP}] done"