ALB Ingresses provide access to Services by using Application Load Balancer (ALB). ALB Ingresses are suitable for handling traffic fluctuations. This topic describes how to use an ALB Ingress to expose Services in a Container Service for Kubernetes (ACK) cluster.

Background information

An Ingress provides a collection of rules that manage external access to Services in a cluster. You can configure forwarding rules to assign Services different externally-accessible URLs. However, NGINX Ingresses and Layer 4 Server Load Balancer (SLB) Ingresses cannot meet the requirements of cloud-native applications, such as complex routing, multiple application layer protocols support (such as QUIC), and balancing of heavy traffic loads at Layer 7.

Prerequisites

  • The ALB Ingress controller is installed.
    • When you create an ACK cluster, select ALB Ingress in the Ingress field on the Component Configurations wizard page.
    • If you use an existing cluster that does not have the ALB Ingress controller installed, refer to Manage system components and install the ALB Ingress controller in the cluster.
  • If you want to expose Services in an ACK dedicated cluster by using an ALB Ingress, you must grant the required permissions to the ALB Ingress controller that is installed in the cluster before you deploy the Services. For more information, see Grant permissions to the ALB Ingress controller in a dedicated Kubernetes cluster.
  • A kubectl client is connected to the cluster. For more information, see Connect to ACK clusters by using kubectl.

Precautions

If you use the Flannel network plug-in, the backend Services of the ALB Ingress must be of the NodePort or LoadBalancer type.

Step 1: Create an AlbConfig object

  1. Create a file named alb-test.yaml and copy the following content into the file. The file is used to create an AlbConfig Object. 
    apiVersion: alibabacloud.com/v1
kind: AlbConfig
metadata:
  name: default
spec:
  config:
    name: alb-test
    addressType: Internet
    zoneMappings:
    - vSwitchId: vsw-uf6ccg2a9g71hx8go****
    - vSwitchId: vsw-uf6nun9tql5t8nh15****
    Parameter Description
    spec.config.name The name of the ALB instance. This parameter is optional.
    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 of the ALB instance. Therefore, the ALB instance is accessible only within the virtual private cloud (VPC) where the ALB instance is deployed.
    zoneMappings The IDs of the vSwitches that are used by the ALB Ingress. You must specify at least two vSwitch IDs and the vSwitches must be deployed in different zones. This parameter is required. For more information about the regions and zones that are supported by ALB Ingresses, see Supported regions and zones.
  2. Run the following command to create an AlbConfig object: 
    kubectl apply -f alb-test.yaml
    Expected output:
    AlbConfig.alibabacloud.com/default created
  3. Create a file named alb.yaml and copy the following content into the file: 
    apiVersion: networking.k8s.io/v1beta1
kind: IngressClass
metadata:
  name: alb
spec:
  controller: ingress.k8s.alibabacloud/alb
  parameters:
    apiGroup: alibabacloud.com
    kind: AlbConfig
    name: default
    apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: alb
spec:
  controller: ingress.k8s.alibabacloud/alb
  parameters:
    apiGroup: alibabacloud.com
    kind: AlbConfig
    name: default

  4. Run the following command to create an IngressClass: 
    kubectl apply -f alb.yaml
    Expected output:
    ingressclass.networking.k8s.io/alb created

Step 2: Deploy applications

  1. Create a cafe-service.yaml file and copy the following content into the file. The file is used to deploy two Deployments named coffee and tea and two Services named coffee and tea. 
    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
  type: NodePort
---
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
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
  selector:
    app: tea
  type: NodePort
  2. 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
  3. Run the following command to query the status of the Services that you created: 
    kubectl get svc,deploy

    Expected output:

    NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
coffee-svc   NodePort    172.16.231.169   <none>        80:31124/TCP   6s
tea-svc      NodePort    172.16.38.182    <none>        80:32174/TCP   5s
NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/coffee   2         2         2            2           1m
deploy/tea      1         1         1            1           1m

Step 3: Configure an Ingress

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

  2. 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 "cafe-ingress" created
  3. Run the following command to query the IP address of the ALB instance: 
    kubectl get ing

    Expected output:

    NAME           CLASS    HOSTS   ADDRESS                                               PORTS   AGE
cafe-ingress   <none>   *       alb-m551oo2zn63yov****.cn-hangzhou.alb.aliyuncs.com   80      50s

Step 4: Access the service

  • After you obtain the IP address of the ALB instance, use one of the following methods to access the coffee Service:
    • Access the coffee Service by using a browser. 1
    • Access the coffee Service by using a CLI. 
      curl http://alb-m551oo2zn63yov****.cn-hangzhou.alb.aliyuncs.com/coffee
  • After you obtain the IP address of the ALB instance, use one of the following methods to access the tea Service:
    • Access the tea Service by using a browser. SLB2
    • Access the tea Service by using a CLI. 
      curl http://alb-m551oo2zn63yov****.cn-hangzhou.alb.aliyuncs.com/tea