Redis in Kubernetes doesn't connect with node

Question

I'm trying to learn DevOps and having issues using Kube.netes with redis and my node.js app

My node.js app connects to redis with following code:

const redis = require('redis');
const client = redis.createClient(process.env.REDIS_URL);
module.exports =  client

My redis.yaml file with a deployment and service :

---
apiVersion: apps/v1  # API version
kind: Deployment
metadata:
  name: redis-master # Unique name for the deployment
  labels:
    app: redis       # Labels to be applied to this deployment
spec:
  selector:
    matchLabels:     # This deployment applies to the Pods matching these labels
      app: redis
      role: master
      tier: backend
  replicas: 1        # Run a single pod in the deployment
  template:          # Template for the pods that will be created by this deployment
    metadata:
      labels:        # Labels to be applied to the Pods in this deployment
        app: redis
        role: master
        tier: backend
    spec:            # Spec for the container which will be run inside the Pod.
      containers:
      - name: master
        image: redis
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
        - containerPort: 6379
---        
apiVersion: v1
kind: Service        # Type of Kubernetes resource
metadata:
  name: redis-master # Name of the Kubernetes resource
  labels:            # Labels that will be applied to this resource
    app: redis
    role: master
    tier: backend
spec:
  ports:
  - port: 6379       # Map incoming connections on port 6379 to the target port 6379 of the Pod
    targetPort: 6379
  selector:          # Map any Pod with the specified labels to this service
    app: redis
    role: master
    tier: backend

my app.yaml file with a deployment and service :

---
apiVersion: apps/v1
kind: Deployment                 # Type of Kubernetes resource
metadata:
  name: go-redis-app             # Unique name of the Kubernetes resource
spec:
  replicas: 3                    # Number of pods to run at any given time
  selector:
    matchLabels:
      app: go-redis-app          # This deployment applies to any Pods matching the specified label
  template:                      # This deployment will create a set of pods using the configurations in this template
    metadata:
      labels:                    # The labels that will be applied to all of the pods in this deployment
        app: go-redis-app 
    spec:
      containers:
      - name: go-redis-app
        image: alsoares59/devops-project:latest
        imagePullPolicy: IfNotPresent
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
          - containerPort: 8080  # Should match the port number that the Go application listens on    
        env:                     # Environment variables passed to the container
          - name: REDIS_URL
            value: redis-master
          - name: PORT
            value: "3000"
---
apiVersion: v1
kind: Service                    # Type of kubernetes resource
metadata:
  name: go-redis-app-service     # Unique name of the resource
spec:
  type: NodePort                 # Expose the Pods by opening a port on each Node and proxying it to the service.
  ports:                         # Take incoming HTTP requests on port 9090 and forward them to the targetPort of 8080
  - name: http
    port: 9090
    targetPort: 8080
  selector:
    app: go-redis-app            # Map any pod with label `app=go-redis-app` to this service

For some reason when creating those deployments and services, my node app will crash saying it can't connect to redis .

[vagrant@centos-minikube k8s]$ kubectl logs go-redis-app-6b687c7bd6-6npt7

> express-redis@1.0.0 start /
> node src/server.js

redis server should be at redis-master
Server listening on port 3000
events.js:292
      throw er; // Unhandled 'error' event
      ^

Error: connect ENOENT redis-master
    at PipeConnectWrap.afterConnect [as oncomplete] (net.js:1146:16)
Emitted 'error' event on RedisClient instance at:
    at RedisClient.on_error (/node_modules/redis/index.js:341:14)
    at Socket.<anonymous> (/node_modules/redis/index.js:222:14)
    at Socket.emit (events.js:315:20)
    at emitErrorNT (internal/streams/destroy.js:106:8)
    at emitErrorCloseNT (internal/streams/destroy.js:74:3)
    at processTicksAndRejections (internal/process/task_queues.js:80:21) {
  errno: -2,
  code: 'ENOENT',
  syscall: 'connect',
  address: 'redis-master'
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! express-redis@1.0.0 start: `node src/server.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the express-redis@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2020-12-23T13_39_56_529Z-debug.log

What am I missing? I know Kube.netes should translate redis-master into redis 's pod IP address but I don't know if he is doing it well.

Answer 1

I found it myself. I had to change the redis-client.js to this:

const redis = require('redis');
console.log("redis server should be at "+process.env.REDIS_URL)
const client = redis.createClient({
    host: process.env.REDIS_URL,
    port: process.env.REDIS_PORT
});

module.exports =  client