fix: restore Mailu SQLite database in place

abra.sh

@@ -2,3 +2,4 @@ export CERTDUMPER_POST_VERSION=v1
 export POSTFIX_OVERRIDE_VERSION=v17
 export SENDER_LOGIN_VERSIONS=v2
 export BACKUP_SQLITE_VERSION=v1
+export RESTORE_SQLITE_VERSION=v1

compose.yml

@@ -96,7 +96,7 @@ services:
         - "traefik.http.routers.${STACK_NAME}.rule=Host(`${DOMAIN}`)"
         - "traefik.http.routers.${STACK_NAME}.tls.certresolver=${LETS_ENCRYPT_ENV}"
         - "traefik.http.routers.${STACK_NAME}.entrypoints=web-secure"
-        - "coop-cloud.${STACK_NAME}.version=4.0.0+2024.06.67"
+        - "coop-cloud.${STACK_NAME}.version=4.0.1+2024.06.67"
         - "backupbot.backup=${ENABLE_BACKUPS:-true}"
         - "backupbot.backup.volumes.traefik_letsencrypt=false"
         - "backupbot.backup.volumes.mailu.path=backup"
@@ -122,9 +122,13 @@ services:
       - source: backup_sqlite
         target: /usr/local/bin/backup_sqlite.py
         mode: 0444
+      - source: restore_sqlite
+        target: /usr/local/bin/restore_sqlite.py
+        mode: 0444
     deploy:
       labels:
         backupbot.backup.pre-hook: "python3 /usr/local/bin/backup_sqlite.py"
+        backupbot.restore.post-hook: "python3 /usr/local/bin/restore_sqlite.py"
 
   imap:
     image: ghcr.io/mailu/dovecot:2024.06.67
@@ -234,6 +238,9 @@ configs:
   backup_sqlite:
     name: ${STACK_NAME}_backup_sqlite_${BACKUP_SQLITE_VERSION}
     file: backup_sqlite.py
+  restore_sqlite:
+    name: ${STACK_NAME}_restore_sqlite_${RESTORE_SQLITE_VERSION}
+    file: restore_sqlite.py
 
 
 secrets:

restore_sqlite.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+"""Restore Mailu's SQLite snapshot without replacing the live database inode."""
+
+import sqlite3
+from pathlib import Path
+
+backup_path = Path("/data/backup/main.db")
+live_path = Path("/data/main.db")
+
+# The source and destination must already exist. A missing snapshot or live
+# database is a restore failure, not a reason to create an empty database.
+with sqlite3.connect(
+    f"{backup_path.as_uri()}?mode=ro", uri=True, timeout=60
+) as source:
+    if source.execute("PRAGMA integrity_check").fetchall() != [("ok",)]:
+        raise RuntimeError(f"Invalid SQLite snapshot: {backup_path}")
+    with sqlite3.connect(
+        f"{live_path.as_uri()}?mode=rw", uri=True, timeout=60
+    ) as destination:
+        source.backup(destination, pages=256, sleep=0.1)
+
+print(f"SQLite restore complete: {live_path}", flush=True)