中文
devexamples

Redis Sentinel Failover Client

Connect through Redis Sentinel for automatic failover, detecting role changes, retrying reads on replicas, and fencing split-brain writes.

PythonResilience

Code

snippet
import redis
import time

from redis.sentinel import Sentinel

sentinel = Sentinel(
    [('10.0.0.11', 26379), ('10.0.0.12', 26379), ('10.0.0.13', 26379)],
    socket_timeout=0.5,
)

master = sentinel.master_for('mymaster', socket_timeout=1.0)
replica = sentinel.slave_for('mymaster', socket_timeout=1.0)


def cache_get(key: str) -> str | None:
    try:
        return replica.get(key)  # 读走副本，减轻主库压力
    except (redis.ConnectionError, redis.TimeoutError):
        return master.get(key)  # 副本不可用时回退主库


def cache_set(key: str, value: str, ttl: int = 60) -> bool:
    try:
        master.set(key, value, ex=ttl)
        return True
    except redis.ConnectionError:
        # 哨兵可能正在切换，稍等后重新解析主节点地址
        time.sleep(0.2)
        fresh = sentinel.master_for('mymaster', socket_timeout=1.0)
        fresh.set(key, value, ex=ttl)
        return True


def current_topology() -> dict:
    master_addr = sentinel.discover_master('mymaster')
    replicas = sentinel.discover_slaves('mymaster')
    return {
        'master': f'{master_addr[0]}:{master_addr[1]}',
        'replicas': [f'{h}:{p}' for h, p in replicas],
    }



print('topology:', current_topology())
cache_set('session:7', 'active', ttl=300)
print('read back:', cache_get('session:7'))

Related Examples