sonic-buildimage/dockers/docker-database/flush_unused_database

#!/usr/bin/python3
from swsscommon import swsscommon
import subprocess
import time
import syslog

while(True):
    output = subprocess.Popen(['sonic-db-cli', 'PING'], stdout=subprocess.PIPE, text=True).communicate()[0]
    if 'PONG' in output:
        break
    time.sleep(1)

instlists = swsscommon.SonicDBConfig.getInstanceList()
for instname, v in instlists.items():
    insthost = v.hostname
    instsocket = v.unixSocketPath

    dblists = swsscommon.SonicDBConfig.getDbList()
    for dbname in dblists:
        dbid = swsscommon.SonicDBConfig.getDbId(dbname)
        dbinst = swsscommon.SonicDBConfig.getDbInst(dbname)

        # this DB is on current instance, skip flush
        if dbinst == instname:
            continue

        try:
            # Migrate code from py-redis to swsscommon, original code:
            #    r = redis.Redis(host=insthost, unix_socket_path=instsocket, db=dbid)
            #    py-redis will use TCP connection when unix_socket_path is None
            #    https://github.com/redis/redis-py/blob/d95d8a24ed2af3eae80b7b0f14cbccc9dbe86e96/redis/client.py#L1006
            if instsocket is not None:
                # connect with Unix socket
                connector = swsscommon.DBConnector(dbid, instsocket, 0)
            else:
                # connect with TCP socket
                port = swsscommon.SonicDBConfig.getDbPort(dbname);
                connector = swsscommon.DBConnector(dbid, insthost, port, 0)

            connector.flushdb()
        except RuntimeError:
           syslog.syslog(syslog.LOG_INFO,"flushdb:Redis Unix Socket connection error for path {} and dbaname {}".format(instsocket, dbname))