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"]