将 redis-sentinel 连接到 Kubernetes 上的 redis-master

Question

I have successfully connected the redis-slaves with the redis-master on Kubernetes using the.yaml manifest file that is deployed as pods on kubernetes.

But when I am trying to connect the redis-sentinel to master it gives connection refused "Could not connect to Redis at 127.0.0.1:26379: Connection refused not connected>"

Below is the redis master, slave and sentinel manifest file:

Redis-Master.yaml

kind: Deployment
metadata:
  labels:
    name: redis
    redis-sentinel: "true"
    role: master
  name: redis-master
spec:
  selector:
    matchLabels:
      app: redis
      role: master
      tier: backend
  replicas: 1
  template:
    metadata:
      labels:
        app: redis
        role: master
        tier: backend
    spec:
      containers:
      - name: master
        image: k8s.gcr.io/redis:e2e  # or just image: redis
        env:
          - name: MASTER
            value: "true"
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
        - containerPort: 6379

Redis-Slave.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-slave
  labels:
    app: redis
    role: slave
    tier: backend
spec:
  strategy:
    type: RollingUpdate
  replicas: 3
  selector:
    matchLabels:
      app: redis
      role: slave
      tier: backend
  template:
    metadata:
      labels:
        app: redis
        role: slave
        tier: backend
    spec:
      containers:
        - name: slave
          image: gcr.io/google_samples/gb-redisslave:v3
          ports:
            - name: redis-server
              containerPort: 6379
          env:
            - name: ALLOW_EMPTY_PASSWORD
              value: "yes"
            - name: REDIS_REPLICATION_MODE
              value: slave
            - name: REDIS_MASTER_HOST
              value: redis-master
            - name: REDIS_MASTER_PORT_NUMBER
              value: "6379"

Redis-sentinel

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-sentinel
  labels:
    app: redis
    role: sentinel  
    tier: backend
spec:
  strategy:
    type: RollingUpdate
  replicas: 3
  selector:
    matchLabels:
      app: redis
      role: sentinel
      tier: backend
  template:
    metadata:
      labels:
        name: redis-sentinel
        redis-sentinel: "true"
        app: redis
        role: sentinel
        tier: backend
    spec:
      containers:
        - name: sentinel
          image: gcr.io/google_samples/gb-redisslave:v3
          ports:
            - name: redis-sentinel
              containerPort: 26379
          env:
            - name: ALLOW_EMPTY_PASSWORD
              value: "yes"
            - name: REDIS_REPLICATION_MODE
              value: sentinel
            - name: REDIS_MASTER_HOST
              value: redis-master
            - name: REDIS_MASTER_PORT_NUMBER
              value: "6379"   

Can you tell me where am I getting wrong with the redis-sentinel manifest file?

Answer 1

There are few things you need to consider when deploying Redis-sentinel that can go wrong in your particular use case:

1. Check firewall rules. Make sure port 26379 of your servers is open. Sentinels by default run listening for connections to TCP port 26379. Otherwise Sentinels can't talk and can't agree about what to do.

2. Check your Sentinel configuration file - sentinel.conf and Redis configuration file - redis.conf . It is mandatory to use a configuration file when running Sentinel, as this file will be used by the system in order to save the current state that will be reloaded in case of restarts. Sentinel will simply refuse to start if no configuration file is given or if the configuration file path is not writable.

3. You need at least three Sentinel instances for a robust deployment.

You can find more info regarding some of the above info here .

Please let me know if that helped.

Answer 2

I am just assuming that you are trying to connect to the pod from outside. You are connecting to 127.0.0.1 which does not exist inside the Kubernetes environment. You need to connect to the IP of the Pod which you get by simply running

kubectl describe pod

or you can create a service and use the name of the service as an env variable in the sentinels.

Answer 3

You can't connect it like this. You must check services on Kubernetes. you can see Redis service IP address. you must connect with the IP address