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 Kubernetes cluster. You can configure forwarding rules to assign different externally-accessible URLs to different Services. 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.
- You can install the ALB Ingress controller when you create a cluster by setting the Ingress parameter to ALB Ingress 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.
- A kubectl client is connected to the cluster. For more information, see Obtain the kubeconfig file of a cluster and use kubectl to connect to the cluster.
Precautions
- The version of Kubernetes must be 1.18 or later.
- If you use the Flannel network plug-in, the backend Services of the ALB Ingress must be of the NodePort or LoadBalancer type.
- The names of AlbConfig objects, namespaces, Ingresses, and Services cannot start with aliyun.
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****
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 of the ALB instance. Therefore, the ALB instance is accessible only within the virtual private cloud (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 and the vSwitches must be deployed in different zones. 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 object:
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:
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
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
- 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
- Create a cafe-service.yaml file and copy the following content to the file. The file is used to deploy two Deployments named
coffee
andtea
and two Services namedcoffee
andtea
.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
- 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
- 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
- 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
- Run the following command to configure an externally-accessible domain name and a
path
for thecoffee
andtea
Services separately:kubectl apply -f cafe-ingress.yaml
Expected output:
ingress "cafe-ingress" created
- Run the following command to query the address of 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