How to use ALB Ingresses in Knative - Container Service for Kubernetes

Application Load Balancer (ALB) runs at the application layer and supports protocols such as HTTP, HTTPS, and Quick UDP Internet Connections (QUIC). ALB offers high elasticity and can process a large amount of network traffic at Layer 7. In addition, ALB supports canary releases based on headers and cookies. This topic describes how to use ALB Ingresses in Knative.

Prerequisites

An ACK Serverless cluster or ACK managed cluster is created. For more information, see Create an ACK Serverless cluster or Create an ACK managed cluster.
The ALB Ingress controller is installed.

Configure an ALB Ingress

You can configure an ALB Ingress by using one of the following methods:

Method 1: Select an ALB Ingress when you deploy Knative

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, click the name of the cluster that you want to manage and choose Applications > Knative in the left-side navigation pane.
On the Components tab, click Deploy Knative.
On the Deploy Knative page, select ALB and select at least two vSwitches. For more information about how to create vSwitches, see Create a vSwitch.
After you complete the configuration, click Deploy.

Method 2: Modify the configuration file of Knative to configure an ALB Ingress

If Knative is deployed, you can modify the configuration file of Knative to configure an ALB Ingress. For more information about how to deploy Knative, see Deploy Knative in an ACK cluster and Deploy Knative in an ACK Serverless cluster.

Run the following command to modify the config-network.yaml file:
```
kubectl -n knative-serving edit configmap config-network
```

Refer to the following template to modify and save the config-network.yaml file.

Modify ingress.class: alb.ingress.networking.knative.dev, configure the vswitch-ids parameter, and save the config-network file and exit. For more information about the regions and zones that support ALB Ingresses, see Regions and zones in which ALB is available.

apiVersion: v1
data:
  ...
  ingress.class: alb.ingress.networking.knative.dev # Specify the ALB Ingress controller. 
  vswitch-ids: vsw-uf6kbvc7mccqia2pi****,vsw-uf66scyuw2fncpn38**** # Replace with the IDs of the two vSwitches that you created in different zones. The system automatically binds the vSwitches when you create an ALB instance. 
  ...
kind: ConfigMap
metadata:
  name: config-network
  namespace: knative-serving
  ...

Use an existing ALB Ingress

If Knative is deployed, you can modify the configuration file of Knative to specify an ALB Ingress. For more information about how to deploy Knative, see Deploy Knative in an ACK cluster and Deploy Knative in an ACK Serverless cluster.

Run the following command to modify the config-network.yaml file:
```
kubectl -n knative-serving edit configmap config-network
```

Refer to the following template to modify and save the config-network.yaml file.

Modify ingress.class: alb.ingress.networking.knative.dev in the configuration file and set albconfig to an existing ALB Ingress. You do not need to configure the vswitch-ids parameter.

apiVersion: v1
data:
  ...
  ingress.class: alb.ingress.networking.knative.dev # Specify the ALB Ingress controller. 
  albconfig: alb-dev-albconfig # Specify the name of an existing AlbConfig. You must specify this parameter if you use an existing ALB Ingress. 
  ...
kind: ConfigMap
metadata:
  name: config-network
  namespace: knative-serving
  ...

Use the ALB Ingress to access a Service

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, click the name of the cluster that you want to manage and choose Applications > Knative in the left-side navigation pane.

On the Services tab of the Knative page, set Namespace to default, click Create from Template, copy the following YAML content to the template editor, and then click Create.

The template creates a Service named helloworld-go.

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-go
spec:
  template:
    spec:
      containers:
      - image: registry-vpc.cn-beijing.aliyuncs.com/knative-sample/helloworld-go:73fbdd56
        env:
        - name: TARGET
          value: "Knative"

On the Services page, record the domain name and gateway IP address of the helloworld-go Service in the Default Domain and Gateway columns, respectively.

Run the following command to access the Service named helloworld-go:

curl -H "host: helloworld-go.default.example.com" http://alb-******.cn-beijing.alb.aliyuncs.com	 # Replace the IP address and domain name with the actual values.

Expected output:

Hello Knative!

The output indicates that the Service can be accessed as normal.