refactor(backup): inline backupbot hooks, drop mysql_backup.sh

Move the mysqldump/gunzip commands directly into the
backupbot.backup.pre-hook / backupbot.restore.post-hook label values
on the db service and delete the external mysql_backup.sh + its
config mount + MYSQL_BACKUP_VERSION. Matches the inline pattern used
by akaunting / engelsystem / forgejo and removes one file from the
recipe surface area.

compose.yml

@@ -67,18 +67,14 @@ services:
       MYSQL_ROOT_PASSWORD_FILE: /run/secrets/db_password
     secrets:
       - db_password
-    configs:
-      - source: mysql_backup
-        target: /mysql_backup.sh
-        mode: 0555
     volumes:
       - "mysql:/var/lib/mysql"
     deploy:
       labels:
         - "backupbot.backup=true"
-        - "backupbot.backup.pre-hook=/mysql_backup.sh backup"
+        - 'backupbot.backup.pre-hook=mysqldump -u root -p"$$(cat /run/secrets/db_password)" --single-transaction --routines --triggers --databases ghost | gzip > /var/lib/mysql/backup.sql.gz'
         - "backupbot.backup.volumes.mysql.path=backup.sql.gz"
-        - "backupbot.restore.post-hook=/mysql_backup.sh restore"
+        - 'backupbot.restore.post-hook=gunzip -c /var/lib/mysql/backup.sql.gz | mysql -u root -p"$$(cat /run/secrets/db_password)"'
 
     healthcheck:
       test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-p\"$$(cat /run/secrets/db_password)\""]
@@ -108,6 +104,3 @@ configs:
   ghost_entrypoint:
     name: ${STACK_NAME}_ghost_entrypoint_${GHOST_ENTRYPOINT_VERSION}
     file: entrypoint.sh
-  mysql_backup:
-    name: ${STACK_NAME}_mysql_backup_${MYSQL_BACKUP_VERSION}
-    file: mysql_backup.sh