How to Access Multiple Services in EKS using a Single Application Load Balancer?

Part 1: How to Access a Service in EKS Using an Application Load Balancer?

In Part 1, the AWS Load Balancer Controller was enabled on the EKS cluster.

That Ingress was set up for only one service, though. This post will be about using a single load balancer to access multiple services in EKS.

Photo by Ave Calvar on Unsplash

(Since I explained the installation and configuration of the AWS Load Balancer Controller in the previous post, I will omit it here.)

We will attempt to configure this diagram on AWS:

We will deploy two applications; email-app, payment-app

There will be multiple pods for each application.

00-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: email-app
  name: email-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: email-app
  template:
    metadata:
      labels:
        app: email-app
    spec:
      containers:
      - image: ailhan/web-debug
        name: email-app
        env:
        - name: TEXT
          value: "Hello from the Email App"
        - name: HOSTNAME
          value: "true"
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: payment-app
  name: payment-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: payment-app
  template:
    metadata:
      labels:
        app: payment-app
    spec:
      containers:
      - image: ailhan/web-debug
        name: payment-app
        env:
        - name: TEXT
          value: "Hello from the Payment App"
        - name: HOSTNAME
          value: "true"

Apply:

➜  ~ kubectl apply -f 00-deployment.yaml
deployment.apps/email-app created
deployment.apps/payment-app created

The pods can be exposed using the NodePort Service.

01-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: email-app-expose
spec:
  type: NodePort
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: email-app
---
apiVersion: v1
kind: Service
metadata:
  name: payment-app-expose
spec:
  type: NodePort
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: payment-app

Apply:

➜  ~ kubectl apply -f 01-service.yaml
service/email-app-expose created
service/payment-app-expose created

Let’s create the application load balancer via Ingress (before proceeding, please ensure you’ve installed the AWS Load Balancer Controller from Part 1):

02-ingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: main-lb
  annotations:
    alb.ingress.kubernetes.io/scheme: internet-facing
    alb.ingress.kubernetes.io/target-type: ip
    alb.ingress.kubernetes.io/load-balancer-name: "main-lb"
spec:
  ingressClassName: alb
  rules:
    - http:
        paths:
        - path: /email
          pathType: Prefix
          backend:
            service:
              name: email-app-expose
              port:
                number: 80
        - path: /payment
          pathType: Prefix
          backend:
            service:
              name: payment-app-expose
              port:
                number: 80

Apply:

➜  ~ kubectl apply -f 02-ingress.yaml
ingress.networking.k8s.io/main-lb created

The load balancer has been successfully created:

Let’s examine the application load balancer’s rules:

Let’s test it:

The load balancer distributes the traffic among those services.