连接DCS单机、主备、读写分离、Proxy集群实例

from redis.backoff import ExponentialBackoff
from redis.retry import Retry
from redis.client import Redis
from redis.connection import BlockingConnectionPool
from redis.exceptions import (
    BusyLoadingError,
    ConnectionError,
    TimeoutError
)

redis_client = None


def create_redis_client(context):
    logger = context.getLogger()
    redis_address = context.getUserData("redis_ip_address")
    redis_host = redis_address.split(":")[0]
    redis_port = redis_address.split(":")[1]
    redis_password = context.getUserData("redis_password")
    logger.info("redis host={}".format(redis_host))
    logger.info("redis port={}".format(redis_port))
    retry = Retry(ExponentialBackoff(), 3)
    pool = BlockingConnectionPool(host=redis_host, port=redis_port,
                                  password=redis_password,
                                  max_connections=20, timeout=3,
                                  socket_timeout=2,
                                  socket_connect_timeout=2,
                                  retry=retry,
                                  retry_on_error=[BusyLoadingError,
                                                  ConnectionError,
                                                  TimeoutError],
                                  health_check_interval=60,
                                  decode_responses=True)
    return Redis(connection_pool=pool)


def initializer(context):
    global redis_client
    redis_client = create_redis_client(context)
    redis_client.ping()


def handler(event, context):
    logger = context.getLogger()
    redis_client.set('foo', 'bar')
    value = redis_client.get('foo')
    logger.info("redis get key foo value={}".format(value))
    return value

客户端使用连接池时不要将获取连接的操作放在初始化函数 initializer 方法中，否则只会在初始化时获取一个连接而导致连接池使用无效。当网络抖动时可能会使已获取的连接断连，后续复用该实例的并发请求时可能会因断连而访问redis失败。