[MultiDB] add MultiDB warmboot support - backing up database (#1205)

* lua script to backup all database into one database and create rdb file - following earlier multiDB warmboot design at https://github.com/Azure/SONiC/blob/master/doc/database/multi_database_instances.md
* copy this rdb file as before to WARM_DIR
* restoring database part is in another PR at sonic-buildimage  sonic-net/sonic-buildimage#5773, they depend on each other

scripts/centralize_database

@@ -0,0 +1,62 @@
+#!/usr/bin/python
+from __future__ import print_function
+import sys
+import swsssdk
+import redis
+import argparse
+
+def centralize_to_target_db(target_dbname):
+ target_dbport = swsssdk.SonicDBConfig.get_port(target_dbname)
+ target_dbhost = swsssdk.SonicDBConfig.get_hostname(target_dbname)
+
+ dblists = swsssdk.SonicDBConfig.get_dblist()
+ for dbname in dblists:
+ dbport = swsssdk.SonicDBConfig.get_port(dbname)
+ dbhost = swsssdk.SonicDBConfig.get_hostname(dbname)
+ # if the db is on the same instance, no need to move
+ if dbport == target_dbport and dbhost == target_dbhost:
+ continue
+
+ dbsocket = swsssdk.SonicDBConfig.get_socket(dbname)
+ dbid = swsssdk.SonicDBConfig.get_dbid(dbname)
+
+ r = redis.Redis(host=dbhost, unix_socket_path=dbsocket, db=dbid)
+
+ script = """
+ local cursor = 0;
+ repeat
+ local dat = redis.call('SCAN', cursor, 'COUNT', 7000);
+ cursor = dat[1];
+ redis.call('MIGRATE', KEYS[1], KEYS[2], '', KEYS[3], 5000, 'COPY', 'REPLACE', 'KEYS', unpack(dat[2]));
+ until cursor == '0';
+ """
+ r.eval(script, 3, target_dbhost, target_dbport, dbid)
+
+ #SAVE rdb file
+ r = redis.Redis(host=target_dbhost, port=target_dbport)
+ r.save()
+
+def main():
+ parser = argparse.ArgumentParser(description='centralize all db data into one db instances',
+ formatter_class=argparse.RawTextHelpFormatter,
+ epilog=
+"""
+Example : centralize_database APPL_DB
+""")
+ parser.add_argument('target_db', type=str, help='move all db data into the instance where target db locates')
+ args = parser.parse_args()
+
+ if args.target_db:
+ try:
+ centralize_to_target_db(args.target_db)
+ print(swsssdk.SonicDBConfig.get_instancename(args.target_db))
+ except Exception as ex:
+ template = "An exception of type {0} occurred. Arguments:\n{1!r}"
+ message = template.format(type(ex).__name__, ex.args)
+ print(message, file=sys.stderr)
+ sys.exit(1)
+ else:
+ parser.print_help()
+
+if __name__ == "__main__":
+ main()

scripts/fast-reboot

@@ -247,10 +247,13 @@ function backup_database()
  end
  end
  " 0 > /dev/null
- sonic-db-cli SAVE > /dev/null
- #TODO : need a script to copy all rdb files if there is multiple db instances config
- docker cp database:/var/lib/redis/$REDIS_FILE $WARM_DIR
- docker exec -i database rm /var/lib/redis/$REDIS_FILE
+
+ # move all db data into the instance where APPL_DB locates
+ target_db_inst=`centralize_database APPL_DB`
+
+ # Dump redis content to a file 'dump.rdb' in warmboot directory
+ docker cp database:/var/lib/$target_db_inst/$REDIS_FILE $WARM_DIR
+ docker exec -i database rm /var/lib/$target_db_inst/$REDIS_FILE
 }
 
 function setup_control_plane_assistant()

setup.py

@@ -110,7 +110,8 @@
  'scripts/warm-reboot',
  'scripts/watermarkstat',
  'scripts/watermarkcfg',
- 'scripts/sonic-kdump-config'
+ 'scripts/sonic-kdump-config',
+ 'scripts/centralize_database'
  ],
  entry_points={
  'console_scripts': [