Access Services by using an ALB Ingress - Container Service for Kubernetes

Application Load Balancer (ALB) Ingresses support HTTP, HTTPS, and QUIC and meet the requirement of cloud-native applications for high elasticity and Layer 7 traffic management on a large scale. ALB Ingresses are also compatible with NGINX Ingresses. In addition, ALB Ingresses support complex routes and automatic TLS certificate management to allow you to flexibly manage traffic. You can configure Ingress rules to access different Services in a cluster through different URLs.

Prerequisites

An ACK Serverless cluster is created and the cluster runs Kubernetes 1.18 or later. For more information, see ACK Serverless quick start.
Two vSwitches that reside in different zones of the virtual private cloud (VPC) where the ACK cluster is deployed are created. For more information, see Create and manage a vSwitch.
The ALB Ingress controller is installed in the cluster. For more information, see Manage the ALB Ingress controller.
The kubectl client is connected to the ACK Serverless cluster. For more information, see Connect to an ACK cluster by using kubectl.

Usage notes

If you use the Flannel network plug-in, the backend Services of the ALB Ingress gateway must be of the NodePort or LoadBalancer type.
The names of AlbConfig objects, namespaces, Ingresses, and Services cannot start with aliyun.
Earlier NGINX Ingress controller versions cannot recognize the spec : ingressClassName field in the Ingress resource. If an earlier NGINX Ingress controller version is installed and both NGINX Ingresses and ALB Ingresses are used in your ACK cluster, the ALB Ingresses may be reconciled by the NGINX Ingress controller. To avoid this problem, update the NGINX Ingress controller at the earliest opportunity or use annotations to specify the IngressClasses of ALB Ingresses. For more information, see Update the NGINX Ingress controller or Advanced ALB Ingress configurations.

Step 1: Create an AlbConfig object

Create a file named alb-test.yaml and copy the following content to the file. The file is used to create an AlbConfig Object.

apiVersion: alibabacloud.com/v1
kind: AlbConfig
metadata:
  name: alb-demo
spec:
  config:
    name: alb-test
    addressType: Internet
    zoneMappings:
    - vSwitchId: vsw-uf6ccg2a9g71hx8go****
    - vSwitchId: vsw-uf6nun9tql5t8nh15****
  listeners:
    - port: 80
      protocol: HTTP

Parameter	Description
spec.config.name	The name of the ALB instance. This parameter is optional.
spec.config.addressType	The type of IP address that the ALB instance uses to provide services. This parameter is required. Valid values: Internet: The ALB instance uses a public IP address. The domain name of the Ingress is resolved to the public IP address of the ALB instance. Therefore, the ALB instance is accessible over the Internet. This is the default value. Intranet: The ALB instance uses a private IP address. The domain name of the Ingress is resolved to the private IP address. Therefore, the ALB instance is accessible only within the VPC where the ALB instance is deployed.
spec.config.zoneMappings	The IDs of the vSwitches that are used by the ALB Ingress. You must specify at least two vSwitch IDs. The vSwitches must be deployed in different zones and in the VPC where the cluster resides. The zones of the vSwitches must be supported by ALB Ingresses. This parameter is required. For more information about the regions and zones that are supported by ALB Ingresses, see Supported regions and zones.

Run the following command to create an AlbConfig:

kubectl apply -f alb-test.yaml

Expected output:

albconfig.alibabacloud.com/alb-demo created

Create a file named alb.yaml and copy the following content to the file:

Clusters that run Kubernetes 1.19 or later

apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: alb
spec:
  controller: ingress.k8s.alibabacloud/alb
  parameters:
    apiGroup: alibabacloud.com
    kind: AlbConfig
    name: alb-demo

Clusters that run Kubernetes versions earlier than V1.19

apiVersion: networking.k8s.io/v1beta1
kind: IngressClass
metadata:
  name: alb
spec:
  controller: ingress.k8s.alibabacloud/alb
  parameters:
    apiGroup: alibabacloud.com
    kind: AlbConfig
    name: alb-demo

Run the following command to create an IngressClass:

  kubectl apply -f alb.yaml

Expected output:

ingressclass.networking.k8s.io/alb created

Step 2: Deploy Services

Create a cafe-service.yaml file and copy the following content to the file. The file is used to deploy two Deployments named coffee and tea and two Services named coffee and tea.

View the content of the YAML file

apiVersion: apps/v1
kind: Deployment
metadata:
  name: coffee
spec:
  replicas: 2
  selector:
    matchLabels:
      app: coffee
  template:
    metadata:
      labels:
        app: coffee
    spec:
      containers:
      - name: coffee
        image: registry.cn-hangzhou.aliyuncs.com/acs-sample/nginxdemos:latest
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: coffee-svc
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
  selector:
    app: coffee
  clusterIP: None
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tea
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tea
  template:
    metadata:
      labels:
        app: tea
    spec:
      containers:
      - name: tea
        image: registry.cn-hangzhou.aliyuncs.com/acs-sample/nginxdemos:latest
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: tea-svc
  labels:
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
  selector:
    app: tea
  clusterIP: None

Run the following command to deploy the Deployments and Services:

kubectl apply -f cafe-service.yaml

Expected output:

deployment "coffee" created
service "coffee-svc" created
deployment "tea" created
service "tea-svc" created

Query the status of the Deployments and Services.

Run the following command to query the deployment progress of the application:

kubectl get deploy

Expected output:

NAME                             READY   UP-TO-DATE   AVAILABLE   AGE
coffee                           1/2     2            1           2m26s
tea                              1/1     1            1           2m26s

Run the following command to query the status of Services:

kubectl get svc

Expected output:

NAME                          TYPE           CLUSTER-IP       EXTERNAL-IP           PORT(S)                 AGE
coffee-svc                    NodePort       172.16.XX.XX     <none>                80:32056/TCP            9m38s
tea-svc                       NodePort       172.16.XX.XX     <none>                80:31696/TCP            9m38s

Step 3: Configure an ALB Ingress

Create a file named cafe-ingress.yaml and copy the following content to the file:

Clusters that run Kubernetes 1.19 or later

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress 
spec:
  ingressClassName: alb
  rules:
   - host: demo.domain.ingress.top
     http:
      paths:
      # Configure a context path.
      - path: /tea
        pathType: ImplementationSpecific
        backend:
          service:
            name: tea-svc
            port:
              number: 80
      # Configure a context path.
      - path: /coffee
        pathType: ImplementationSpecific
        backend:
          service:
            name: coffee-svc
            port: 
              number: 80

Clusters that run Kubernetes versions earlier than V1.19

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: cafe-ingress
spec:
  ingressClassName: alb
  rules:
   - host: demo.domain.ingress.top
     http:
      paths:
      # Configure a context path. 
      - path: /tea
        backend:
          serviceName: tea-svc
          servicePort: 80
      # Configure a context path. 
      - path: /coffee
        backend:
          serviceName: coffee-svc
          servicePort: 80

Run the following command to configure an externally-accessible domain name and a path for the coffee and tea Services separately:
```
kubectl apply -f cafe-ingress.yaml
```
Expected output:
```
ingress.networking.k8s.io/cafe-ingress created
```

Run the following command to query the domain name of the Ingress used to expose the ALB instance:

kubectl get ing

Expected output:

NAME           CLASS    HOSTS                         ADDRESS                                               PORTS   AGE
cafe-ingress   alb      demo.domain.ingress.top       alb-m551oo2zn63yov****.cn-hangzhou.alb.aliyuncs.com   80      50s

Step 4: Access the Services

After you obtain the address of the ALB instance, use the CLI to access the coffee Service:

curl -H Host:demo.domain.ingress.top http://alb-lhwdm5c9h8lrcm****.cn-hangzhou.alb.aliyuncs.com/coffee

After you obtain the address of the ALB instance, use the CLI to access the tea Service:

curl -H Host:demo.domain.ingress.top http://alb-lhwdm5c9h8lrcm****.cn-hangzhou.alb.aliyuncs.com/tea

References

For more information about advanced ALB Ingress configurations, such as forwarding requests destined for different domain names or URLs to different backend server groups, health checks, redirecting requests from HTTP to HTTPS, canary releases, and custom listener ports, see Advanced ALB Ingress configurations.
For more information about how to configure custom ALB Ingress routing rules, forwarding conditions, and actions, see Customize the routing rules of an ALB Ingress.
For more information about how to configure an HTTPS listener to forward HTTPS requests, see Use an ALB Ingress to configure certificates for an HTTPS listener.
For more information about how to troubleshoot ALB Ingress issues, see ALB Ingress FAQ.