Kubernetes中Redis主从集群部分Pod无法写入的问题求助
2026-8-6
问题：Kubernetes Redis StatefulSet仅主节点可写入，副本节点写入报错
尝试连接Kubernetes Pod中的Redis时，发现仅1个Pod（redis-0）可以正常读写，其余Pod执行写入操作时均报错：ReplyError: READONLY You can't write against a read only replica.
报错示例
ReplyError: READONLY You can't write against a read only replica.
相关配置文件
pv.yaml
apiVersion: v1 kind: PersistentVolume metadata: name: local-pv1 spec: storageClassName: local-storage capacity: storage: 1Gi accessModes: - ReadWriteOnce hostPath: path: "/storage/data1" --- apiVersion: v1 kind: PersistentVolume metadata: name: local-pv2 spec: storageClassName: local-storage capacity: storage: 1Gi accessModes: - ReadWriteOnce hostPath: path: "/storage/data2" --- apiVersion: v1 kind: PersistentVolume metadata: name: local-pv3 spec: storageClassName: local-storage capacity: storage: 2Gi accessModes: - ReadWriteOnce hostPath: path: "/storage/data3"
redis-service.yaml
apiVersion: v1 kind: Service metadata: name: redis spec: clusterIP: None ports: - port: 6379 targetPort: 6379 name: redis selector: app: redis
redis-statefulset.yaml
apiVersion: apps/v1 kind: StatefulSet metadata: name: redis spec: serviceName: redis replicas: 6 selector: matchLabels: app: redis template: metadata: labels: app: redis spec: initContainers: - name: config image: redis:alpine command: [ "sh", "-c" ] args: - | cp /tmp/redis/redis.conf /etc/redis/redis.conf echo "finding master..." MASTER_FDQN=`hostname -f | sed -e 's/redis-[0-9]\./redis-0./'` if [ "$(redis-cli -h sentinel -p 5000 ping)" != "PONG" ]; then echo "master not found, defaulting to redis-0" if [ "$(hostname)" == "redis-0" ]; then echo "this is redis-0, not updating config..." else echo "updating redis.conf..." echo "slaveof $MASTER_FDQN 6379" >> /etc/redis/redis.conf fi else echo "sentinel found, finding master" MASTER="$(redis-cli -h sentinel -p 5000 sentinel get-master-addr-by-name mymaster | grep -E '(^redis-\d{1,})|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})')" echo "master found : $MASTER, updating redis.conf" echo "slaveof $MASTER 6379" >> /etc/redis/redis.conf fi volumeMounts: - name: redis-config mountPath: /etc/redis/ - name: config mountPath: /tmp/redis/ containers: - name: redis image: redis:alpine command: ["redis-server"] args: ["/etc/redis/redis.conf"] ports: - containerPort: 6379 name: redis volumeMounts: - name: data mountPath: /data - name: redis-config mountPath: /etc/redis/ volumes: - name: redis-config emptyDir: {} - name: config configMap: name: redis-config volumeClaimTemplates: - metadata: name: data spec: accessModes: [ "ReadWriteOnce" ] storageClassName: "local-storage" resources: requests: storage: 500Mi
sc.yaml
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: local-storage provisioner: kubernetes.io/no-provisioner volumeBindingMode: WaitForFirstConsumer allowVolumeExpansion: true reclaimPolicy: Delete
客户端代码（Main.ts）
import Redis from "ioredis"; const redisClient = new Redis({ port: 6379, host: 'redis', password: "a-very-complex-password-here" }) (() => { setInterval(async () => { try { await redisClient.set("TEST::" + Date.now(),"a") } catch (error) { console.log(error); } },5000) })()
Pod日志
Pod 1（redis-0）日志
[ 'TEST::1672209760072', 'TEST::1672209760073', 'TEST::1672149366766', 'TEST::1672149491854', 'TEST::1672149136595', 'TEST::1672149081725', 'TEST::1672149276699', 'TEST::1672209840134', 'TEST::1672209800104', 'TEST::1672209655044', 'TEST::1672209659981', 'TEST::1672209594929', 'TEST::1672209785102', 'TEST::1672209589922', 'TEST::1672209795107', 'TEST::1672149296731', 'TEST::1672209735048', 'TEST::1672209700017', 'TEST::1672209750066', 'TEST::1672209740054', 'TEST::1672149306733', 'TEST::1672149086555', 'TEST::1672209593891', 'TEST::1672149256729', 'TEST::1672209730062', 'TEST::1672209695012', 'TEST::1672149136714', 'TEST::1672149181721', 'TEST::1672149221659', 'TEST::1672149456827', 'TEST::1672209578963', 'TEST::1672149201722', 'TEST::1672209640039', 'TEST::1672149186635', 'TEST::1672209625042', 'TEST::1672209610038', 'TEST::1672209605038', 'TEST::1672149111711', 'TEST::1672149151714', 'TEST::1672209634958', 'TEST::1672149391784', 'TEST::1672149516863', 'TEST::1672209573871', 'TEST::1672209820125', 'TEST::1672209563958', 'TEST::1672209560752', 'TEST::1672149521868', 'TEST::1672149291714', 'TEST::1672209715059', 'TEST::1672209575748', 'TEST::1672209805109', 'TEST::1672149526866', 'TEST::1672149261689', 'TEST::1672209565751', 'TEST::1672209615041', 'TEST::1672209595035', 'TEST::1672149381772', 'TEST::1672149311728', 'TEST::1672209590040', 'TEST::1672149141599', 'TEST::1672149471832', 'TEST::1672149461828', 'TEST::1672209820119', 'TEST::1672209725060', 'TEST::1672209588961', 'TEST::1672209790098', 'TEST::1672209710024', 'TEST::1672149511859', 'TEST::1672149291731', 'TEST::1672209578882', 'TEST::1672149191723', 'TEST::1672149141712', 'TEST::1672209750070', 'TEST::1672149336740', 'TEST::1672209573963', 'TEST::1672209780096', 'TEST::1672149396786', 'TEST::1672149391782', 'TEST::1672149091708', 'TEST::1672209580751', 'TEST::1672149176629', 'TEST::1672209585036', 'TEST::1672209553962', 'TEST::1672209730046', 'TEST::1672209614945', 'TEST::1672149401788', 'TEST::1672149111579', 'TEST::1672149361761', 'TEST::1672149236728', 'TEST::1672149416802', 'TEST::1672149501854', 'TEST::1672149376772', 'TEST::1672209600035', 'TEST::1672149201646', 'TEST::1672149511861', 'TEST::1672209845144', 'TEST::1672209568866', 'TEST::1672209805112', 'TEST::1672149326734', 'TEST::1672149146601', ... 219 more items ]
Pod 2（redis-1）日志
ReplyError: READONLY You can't write against a read only replica. at parseError (/usr/src/app/node_modules/redis-parser/lib/parser.js:179:12) at parseType (/usr/src/app/node_modules/redis-parser/lib/parser.js:302:14) { command: { name: 'set', args: [ 'UFUK::1672209926379', 'a' ] } } [] ReplyError: READONLY You can't write against a read only replica. at parseError (/usr/src/app/node_modules/redis-parser/lib/parser.js:179:12) at parseType (/usr/src/app/node_modules/redis-parser/lib/parser.js:302:14) { command: { name: 'set', args: [ 'UFUK::1672209926381', 'a' ] } } ReplyError: READONLY You can't write against a read only replica. at parseError (/usr/src/app/node_modules/redis-parser/lib/parser.js:179:12) at parseType (/usr/src/app/node_modules/redis-parser/lib/parser.js:302:14) { command: { name: 'set', args: [ 'UFUK::1672209931382', 'a' ] } } []
解决方案
问题根源
当前Redis StatefulSet是主从架构：redis-0是主节点（可读写），其余Pod都是从节点（只读，仅同步主节点数据）。而客户端连接的是Headless Service（redis），它会将请求轮询分发到所有Redis Pod，当写请求打到从节点时就会触发READONLY报错。
方案1：部署Redis Sentinel实现自动主从发现与读写分离
- 部署Redis Sentinel：创建Sentinel的StatefulSet/Deployment，配置它监控Redis主节点（mymaster）。Sentinel会自动监控主节点状态，当主节点故障时自动切换新的主节点，并通知客户端更新主节点地址。
- 修改客户端代码：使用ioredis的Sentinel模式连接，让客户端自动发现主节点，写操作发往主节点，读操作可选择发往从节点：
import Redis from "ioredis"; // 连接Sentinel集群，自动发现主节点 const redisClient = new Redis({ sentinels: [ { host: 'sentinel-0.sentinel', port: 26379 }, { host: 'sentinel-1.sentinel', port: 26379 }, { host: 'sentinel-2.sentinel', port: 26379 } ], name: 'mymaster', // Sentinel监控的主节点名称 password: "a-very-complex-password-here" }) // 写操作自动发往主节点 (() => { setInterval(async () => { try { await redisClient.set("TEST::" + Date.now(),"a") } catch (error) { console.log(error); } },5000) })()
方案2：创建专属Service指向主节点
如果不需要自动故障切换，可以直接创建一个Service固定指向redis-0（主节点），客户端连接这个Service进行写操作：
apiVersion: v1 kind: Service metadata: name: redis-master spec: ports: - port: 6379 targetPort: 6379 selector: statefulset.kubernetes.io/pod-name: redis-0
修改客户端代码的host为redis-master：
const redisClient = new Redis({ port: 6379, host: 'redis-master', // 指向主节点专属Service password: "a-very-complex-password-here" })
补充说明
当前StatefulSet的initContainer中已经包含了Sentinel相关的配置逻辑，但实际并未部署Sentinel组件，所以所有非redis-0的Pod默认被配置为redis-0的从节点。如果选择方案1，需要完善Sentinel的部署，确保Sentinel集群正常运行，这样主节点故障时能自动切换，客户端也能自动感知新的主节点。
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