Create Ingress With Default Backend¶

A defaultBackend is often configured in an Ingress controller to service any requests that do not match a path in the spec.

Let's see this in action!

Docker Images¶

Here is the Docker Image used in this tutorial: reyanshkharga/nodeapp:v1

Step 1: Create a Deployment¶

First, let's create a deployment as follows:

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - name: nodeapp
        image: reyanshkharga/nodeapp:v1
        imagePullPolicy: Always
        ports:
          - containerPort: 5000

Apply the manifest to create the Deployment:

kubectl apply -f my-deployment.yml

Verify deployment and pods:

# List deployments
kubectl get deployments

# List pods
kubectl get pods

Step 2: Create a NodePort Service¶

Let's create a NodePort service as follows:

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apiVersion: v1
kind: Service
metadata:
  name: my-nodeport-service
spec:
  type: NodePort
  selector:
    app: demo
  ports:
    - port: 5000
      targetPort: 5000

Apply the manifest to create the NodePort service:

kubectl apply -f my-nodeport-service.yml

Verify service:

kubectl get svc

Step 3: Create Ingress¶

Now that we have the service ready, let's create an Ingress object:

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apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress
  annotations:
    alb.ingress.kubernetes.io/scheme: internet-facing # Default value is internal
    alb.ingress.kubernetes.io/tags: Environment=dev,Team=DevOps # Optional
    alb.ingress.kubernetes.io/load-balancer-name: my-load-balancer # Optional
spec:
  ingressClassName: alb
  defaultBackend:
    service:
      name: my-nodeport-service
      port:
        number: 5000
  rules:
  - http:
      paths:
      - path: /yXnKHUoJGt
        pathType: Prefix
        backend:
          service:
            name: my-nodeport-service
            port:
              number: 5000

Observe the following:

1. We have used annotations to specify load balancer and target group attributes
2. We have one rule that matches /yXnKHUoJGt path and then routes traffic to default backend which in this case is my-nodeport-service.

Apply the manifest to create ingress:

kubectl apply -f my-ingress.yml

Verify ingress:

kubectl get ingress
{OR}
kubectl get ing

Step 4: Verify AWS Resources in AWS Console¶

Visit the AWS console and verify the resources created by AWS Load Balancer Controller.

Pay close attention to the listener rules. You will observe a default listener rule that was set using defaultBackend.

Also, verify that the ALB was created by AWS Load Balancer Controller. You can check the events in the logs as follows:

kubectl logs -f deploy/aws-load-balancer-controller -n aws-load-balancer-controller --all-containers=true

Troubleshooting¶

If you don't see the load balancer in the AWS console, this means the ingress has some issue. To identify the underlying issue, you can examine the logs of the controller as follows:

# Describe the ingress
kubectl describe ing my-ingress

# View aws load balancer controller logs
kubectl logs -f deploy/aws-load-balancer-controller -n aws-load-balancer-controller --all-containers=true

Clean Up¶

Assuming your folder structure looks like the one below:

|-- manifests
│   |-- my-deployment.yml
│   |-- my-nodeport-service.yml
│   |-- my-ingress.yml

Let's delete all the resources we created:

kubectl delete -f manifests/