Get started with ALB Ingresses - Container Service for Kubernetes

Application Load Balancer (ALB) Ingresses are compatible with NGINX Ingresses and provide improved traffic forwarding capabilities based on ALB instances. ALB Ingresses support complex forwarding, automatic certificate discovery, and the HTTP, HTTPS, and Quick UDP Internet Connections (QUIC) protocols. ALB Ingresses meet the requirements of cloud-native applications for ultra-high elasticity and balancing of heavy traffic loads at Layer 7. You can configure an ALB Ingress in a Container Service for Kubernetes (ACK) cluster to manage traffic. This topic describes how to deploy Services and access the Services by using an ALB Ingress.

Background information

Terms related to ALB Ingresses:

ALB Ingress controller: a Kubernetes component that manages Ingresses. The ALB Ingress controller serves as an entry point in a cluster and routes external traffic to specific Services. The ALB Ingress controller retrieves the changes to Ingresses and AlbConfigs from the API server when the changes are detected. Then, the ALB Ingress controller performs the following operations in sequence: create ALB instances, configure listeners, create Ingress rules, and configure backend server groups.
AlbConfig CRD: Custom resource definitions (CRDs) extend the Kubernetes API and allow you to create custom resources. An AlbConfig corresponds to one ALB instance.
IngressClass: An IngressClass is an attribute of a Kubernetes Ingress that defines the class or identifier of an Ingress controller. IngressClasses allow you to use multiple Ingress controllers in a cluster and specify a controller for each Ingress.
Ingress: An Ingress is a resource object in Kubernetes that defines the forwarding rules and access rules of external traffic. The Ingress controller forwards traffic based on Ingresses. You can configure forwarding rules in ALB Ingresses by using annotations. After the configurations are complete, HTTP or HTTPS requests can be forwarded to the corresponding Services based on the forwarding rules.
Service: In Kubernetes, a Service is an abstract resource object that defines a set of pods that have the same logical feature and allows you to access the pods by using a fixed virtual IP address and port.
A Service provides stable access to an application and allows other applications or services to communicate with backend pods by accessing the virtual IP address and port of the Service. This eliminates the need to obtain the IP address and port of a specific pod. A Service is an abstraction of a backend application that runs on a set of replicated pods.

The following figure shows the relationship between an ALB instance and an ALB Ingress.

Limits

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.
The NGINX Ingress controller of earlier versions cannot recognize the spec:ingressClassName field in the Ingress resource. If both NGINX Ingresses and ALB Ingresses are configured in your ACK cluster, the ALB Ingresses may be reconciled by an earlier version of 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.

Scenarios

In the following examples, NGINX Services are deployed on four pods. This topic uses the examples to describe how to configure an ALB Ingress to forward requests destined for the same domain name but different URL paths.

Frontend request	Destination Service
`demo.domain.ingress.top/coffee`	`coffee` Service
`demo.domain.ingress.top/tea`	`tea` Service

Prerequisites

An ACK managed cluster or ACK dedicated cluster is created and the cluster runs Kubernetes 1.18 or later. For more information, see Create an ACK managed cluster or Create an ACK dedicated cluster.
Optional. kubectl is used to connect to the cluster by using one of the following methods:
- Obtain the kubeconfig file of a cluster and use kubectl to connect to the cluster.
- Use kubectl on Cloud Shell to manage ACK clusters.

Step 1: Install the ALB Ingress controller

To use ALB Ingresses, install the ALB Ingress controller first.

Install the ALB Ingress controller when you create a cluster

When you create an ACK managed cluster or ACK dedicated cluster, select ALB Ingress in the Ingress section.

You can set Gateway Source to New, Existing, or None. The following table describes the three options.

Important

If you select New or Existing, an AlbConfig and IngressClass are automatically created after the ALB Ingress controller is installed. A listener that uses HTTP and listens on port 80 is configured in the AlbConfig.

Comparison item	New	Existing	None
Use scenarios	This is the first time you use ALB Ingresses in the cluster. No AlbConfig exists in the cluster.	You want to use existing ALB instances.	You want to configure an AlbConfig after the ALB Ingress controller is installed.
How it works	After an AlbConfig is created, an ALB instance is automatically created based on the AlbConfig.	An AlbConfig is automatically created. The `id` field is set to the ID of the specified ALB instance.	Only the ALB Ingress controller is installed. No AlbConfig is created.
What to do next	Set Network Type to the type of network used by the ALB instance and set vSwitch to the vSwitch of the ALB instance. Important To ensure high availability, we recommend that you select at least two vSwitches that reside in different zones.	Set ALB Cloud-native Gateway to the ALB instance that you want to use. To use an AlbConfig to specify an ALB instance, see Reuse an existing ALB instance. Important Basic ALB instances are not supported.	Select an existing AlbConfig or create an AlbConfig later.

Install the ALB Ingress controller in an existing cluster

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Operations > Add-ons.
On the Add-ons page, click the Networking tab. In the Networking section, find the ALB Ingress Controller card and click Install in the lower-right corner.

In the Install ALB Ingress Controller dialog box, set Gateway Source to New, Existing, or None. The following table describes the three options.

Important

Comparison item	New	Existing	None
Use scenarios	This is the first time you use ALB Ingresses in the cluster. No AlbConfig exists in the cluster.	You want to use existing ALB instances.	You want to configure an AlbConfig after the ALB Ingress controller is installed.
How it works	After an AlbConfig is created, an ALB instance is automatically created based on the AlbConfig.	An AlbConfig is automatically created. The `id` field is set to the ID of the specified ALB instance.	Only the ALB Ingress controller is installed. No AlbConfig is created.
What to do next	Set Network Type to the type of network used by the ALB instance and set vSwitch to the vSwitch of the ALB instance. Important To ensure high availability, we recommend that you select at least two vSwitches that reside in different zones.	Set ALB Cloud-native Gateway to the ALB instance that you want to use. To use an AlbConfig to specify an ALB instance, see Reuse an existing ALB instance. Important Basic ALB instances are not supported.	Select an existing AlbConfig or create an AlbConfig later.

Click OK.

Note

To use an ALB Ingress to access Services deployed in an ACK dedicated cluster, you need to first authorize the cluster to access the ALB Ingress controller. For more information, see Authorize an ACK dedicated cluster to access the ALB Ingress controller.

Step 2: Deploy backend Services

Use the ACK console

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Workloads > Deployments.

In the upper-right corner of the Custom Resources page, click Create from YAML.

Sample Template: Select Custom from the drop-down list.

Template: Copy and paste the following code to the code editor. The YAML configuration file is used to deploy two Deployments named coffee and tea, and two Services named coffee-svc and tea-svc.

YAML configuration 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
  type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tea
spec:
  replicas: 2
  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

After the configurations are complete, click Create. The Created message appears.
Verify that the Deployments and Services are created.
1. In the left-side pane, choose Workloads > Deployments. The Deployments named coffee and tea are displayed.
2. In the left-side pane, choose Network > Services. The Services named coffee-svc and tea-svc are displayed.

kubectl

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

YAML configuration 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
  type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tea
spec:
  replicas: 2
  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

View the status of the Deployments and Services.

Run the following command to view the status of the Deployments:

kubectl get deployment

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 view the status of the 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: Create an AlbConfig

Note

If you set Gateway Source to New or Existing in Step 1: Install the ALB Ingress controller, an AlbConfig named alb and an IngressClass named alb are automatically created by ALB Ingress controller. You can skip this step.

Use the ACK console

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Workloads > Custom Resources.

In the upper-right corner of the Custom Resources page, click Create from YAML.

Sample Template: Select Custom from the drop-down list.

Template: Copy and paste the following code to the code editor.

YAML configuration file

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

The following table describes the parameters that you can specify.

Parameter	Required	Description
metadata.name	Yes	The name of the AlbConfig. Note The name of the AlbConfig must be unique in the cluster. Therefore, when you create an AlbConfig, make sure that the AlbConfig name is unique to prevent name conflicts.
spec.config.name	No	The name of the ALB instance.
spec.config.addressType	No	The network type of the ALB instance. Valid values: Internet: Internet-facing. This is the default value. The ALB instance provides services to the Internet and is accessible from the Internet. Note An ALB instance is associated with EIPs to provide Internet services. If you use an Internet-facing ALB instance, you are charged instance fees and bandwidth or data transfer fees for the EIPs. For more information, see Pay-as-you-go. Intranet: internal-facing. The ALB instance provides services within a VPC and cannot be accessed from the Internet.
spec.config.zoneMappings	Yes	The ID of the vSwitch that is associated with the ALB instance. For more information about how to create a vSwitch, see Create and manage a vSwitch. Note The specified vSwitch must be deployed in a zone supported by the ALB instance and deployed in the same VPC as the cluster. For more information about the regions and zones supported by ALB, see Regions and zones in which ALB is available. ALB supports multi-zone deployment. If the current region supports two or more zones, select vSwitches in at least two zones to ensure high availability.
spec.listeners	No	The listener port and protocol of the ALB instance. In this example, an HTTP listener that uses port 80 is configured. A listener defines how ALB receives traffic. We recommend that you use the sample listener configurations. Otherwise, you must create a listener before you can use ALB Ingresses.

After the configurations are complete, click Create. The Created message appears.
Verify that the ALB instance is created.
1. Log on to the ALB console.
2. In the top navigation bar, select the region in which the ALB instance is deployed.
3. On the Instances page, verify that the ALB instance named alb-test is displayed in the instance list.

kubectl

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

YAML configuration file

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

The following table describes the parameters that you can specify.

Parameter	Required	Description
metadata.name	Yes	The name of the AlbConfig. Note The name of the AlbConfig must be unique in the cluster. Therefore, when you create an AlbConfig, make sure that the AlbConfig name is unique to prevent name conflicts.
spec.config.name	No	The name of the ALB instance.
spec.config.addressType	No	The network type of the ALB instance. Valid values: Internet: Internet-facing. This is the default value. The ALB instance provides services to the Internet and is accessible from the Internet. Note An ALB instance is associated with EIPs to provide Internet services. If you use an Internet-facing ALB instance, you are charged instance fees and bandwidth or data transfer fees for the EIPs. For more information, see Pay-as-you-go. Intranet: internal-facing. The ALB instance provides services within a VPC and cannot be accessed from the Internet.
spec.config.zoneMappings	Yes	The ID of the vSwitch that is associated with the ALB instance. For more information about how to create a vSwitch, see Create and manage a vSwitch. Note The specified vSwitch must be deployed in a zone supported by the ALB instance and deployed in the same VPC as the cluster. For more information about the regions and zones supported by ALB, see Regions and zones in which ALB is available. ALB supports multi-zone deployment. If the current region supports two or more zones, select vSwitches in at least two zones to ensure high availability.
spec.listeners	No	The listener port and protocol of the ALB instance. In this example, an HTTP listener that uses port 80 is configured. A listener defines how ALB receives traffic. We recommend that you use the sample listener configurations. Otherwise, you must create a listener before you can use ALB Ingresses.

Run the following command to create an AlbConfig:

kubectl apply -f alb-test.yaml

Expected output:

albconfig.alibabacloud.com/alb-demo created

Step 4: Create an IngressClass

We recommend that you create an IngressClass for each AlbConfig.

Note

Use the ACK console

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Workloads > Custom Resources.

In the upper-right corner of the Custom Resources page, click Create from YAML.

Sample Template: Select Custom from the drop-down list.

Template: Copy and paste the following code to the code editor.

YAML configuration file

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

The following table describes the parameters that you can specify.

Parameter	Required	Description
metadata.name	Yes	The name of the IngressClass. Note The name of an IngressClass must be unique in the cluster. Therefore, when you create an IngressClass, make sure that the IngressClass name is unique to prevent name conflicts.
spec.parameters.name	Yes	The name of the associated AlbConfig.

After the configurations are complete, click Create. The Created message appears.
Verify that the IngressClass is created.
1. In the left-side pane, choose Workloads > Custom Resources.
2. On the Custom Resources page, click the Resource Objects tab.
3. In the API Group search box, enter IngressClass. The IngressClass that you create is displayed.

kubectl

Create a file named alb.yaml. Copy and paste the following content to the file.

YAML configuration file

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

The following table describes the parameters that you can specify.

Parameter	Required	Description
metadata.name	Yes	The name of the IngressClass. Note The name of an IngressClass must be unique in the cluster. Therefore, when you create an IngressClass, make sure that the IngressClass name is unique to prevent name conflicts.
spec.parameters.name	Yes	The name of the associated AlbConfig.

Run the following command to create an IngressClass:

  kubectl apply -f alb.yaml

Expected output:

ingressclass.networking.k8s.io/alb created

Step 5: Create an Ingress

Use the ACK console

Log on to the ACK console. In the left-side navigation pane, click Clusters.
On the Clusters page, find the cluster that you want to manage and click its name. In the left-side pane, choose Network > Ingresses.

On the Ingresses page, click Create Ingress. In the Create Ingress dialog box, configure the Ingress.

Parameter	Description	Example
Gateway Type	You can select ALB, MSE Cloud-native Gateway, or Nginx based on your requirements. For more information about the differences among the three gateway types, see Comparison among NGINX Ingresses, ALB Ingresses, and MSE Ingresses.	ALB
Name	Specify the name of the Ingress.	cafe-ingress
Ingress Class	Specify the class of the Ingress.	alb
Listener/Port	The listener port and protocol of the ALB instance that you specify in the AlbConfig. A listener defines how ALB receives traffic.	HTTP:80
Rules	Click +Add Rule to add an Ingress rule. Domain Name: Enter a custom domain name. Mappings: Specify the following parameters: Path: Enter the URL path of the backend Service. In this example, the root path / is used. Rule: You can select Prefix (Prefix-based Match), Exact (Exact Match), or ImplementationSpecific (Default Value). Service: Select the backend Service. Port: Specify the Service port that you want to expose. You can configure multiple paths for a domain name. Click + Add to add a path.	Domain Name: demo.domain.ingress.top Mappings: Path: /tea Rule: ImplementationSpecific. This is the default value. Service: tea-svc Port: 80 Mappings: Path: /coffee Rule: ImplementationSpecific. This is the default value. Service: coffee-svc Port: 80
TLS Settings	Specifies whether to enable TLS authentication. You can enable TLS authentication for the Ingress. Domain Name: the custom domain name. Secret: the Secret used in the cluster. Select a Secret based on your business requirements. To create a Secret, perform the following steps: Click Create to the right of the Secret field. In the Create Secret dialog box, configure the Name, Cert, and Key parameters. Then, click OK. Select the Secret that you create from the Secret drop-down list. You can click + Add to add more TLS certificates. For more information, see Use an ALB Ingress to configure certificates for an HTTPS listener.	Turn off TLS Settings. In this example, you do not need to configure a TLS certificate.
More	Canary Release: Enable canary releases. You can configure canary release rules based on request headers, cookies, and weights. Note You can configure canary release rules based on only one of the following elements: request headers, cookies, and weights. You can also configure canary release rules based on request headers, cookies, and weights at the same time. In this case, request headers, cookies, and weights take effect in descending order of precedence. Based on Request Header: Distribute traffic based on request headers by adding the `nginx.ingress.kubernetes.io/canary-by-header`, `nginx.ingress.kubernetes.io/canary-by-header-value`, or `nginx.ingress.kubernetes.io/canary-by-header-pattern` annotation. Based on Cookie: Distribute traffic based on cookies by adding the `nginx.ingress.kubernetes.io/canary-by-cookie` annotation. Based on Weight: Distribute traffic based on Service weights (integers from 0 to 100) by adding the `nginx.ingress.kubernetes.io/canary-weight` annotation. Protocol: Select the protocol used by the backend Service by adding the `nginx.ingress.kubernetes.io/backend-protocol` annotation. HTTP, HTTPS, gRPC, and gRPCS are supported. Rewrite Path: Add the `nginx.ingress.kubernetes.io/rewrite-target` annotation to rewrite the paths in client requests before the requests are forwarded to the backend Service.	Turn off Canary Release. Use the default values of the Protocol and Rewrite Path parameters. In this example, you do not need to configure these parameters.
Custom Forwarding Rules	You can enable custom forwarding rules to manage inbound traffic in a fine-grained manner. Note You can add up to 10 conditions to a forwarding rule. The following condition types are available in the Add Condition drop-down list: Host: Specifies that only requests that contain the specified one or more domain names are routed. Multiple domain names are treated with an OR relationship. After you specify the domain names, the system adds the `alb.ingress.kubernetes.io/conditions.host-example` annotation. Path: Specifies that only requests that contain the specified one or more paths are routed. Multiple paths are treated with an OR relationship. After you specify the paths, the system adds the `alb.ingress.kubernetes.io/conditions.path-example` annotation. HTTP Header: Specifies that only requests that contain the specified one or more HTTP headers are routed. Each HTTP request header is a key-value pair. For example, you can set the key to `headername` and value to `headervalue1`. Multiple headers are treated with an OR relationship. After you specify the headers, the system adds the `alb.ingress.kubernetes.io/conditions.http-header-example` annotation. The following actions are available in the Action drop-down list: Forward To Forwards the inbound traffic to multiple backend server groups. To forward the inbound traffic, perform the following operations: From the Service Name drop-down list, select the Service that you want to access. From the Port drop-down list, select the port used to connect to the Service. Specify a custom weight for each backend server group. Note If you use the Flannel component for the cluster, the ClusterIP Service is not supported. If you select Forward To from the Action drop-down list, you do not need to configure the Mappings parameter for the rule. Return Fixed Response Specifies that fixed content is returned to clients by using the ALB Ingress. You can specify the status code, content, and type of content that are returned to clients. Configure the Response Status Code, Response Content Type (Optional), and Response Content (Optional) parameters based on your business requirements. Valid values of the Response Content Type parameter: text/plain: indicates that the content is in plaintext. text/css: indicates that the content is in the XML format. text/html: indicates that the content is in the HTML format. application/javascript: indicates that the content is in the JavaScript format. application/json: indicates that the content is in the JSON format. You can specify multiple conditions and actions in a custom forwarding rule. You can configure domain names, paths, and HTTP request headers as forwarding conditions and forward the inbound traffic to backend server groups or return fixed content to clients. For more information, see Customize the routing rules of an ALB Ingress.	Turn off Custom Forwarding Rules. In this example, you do not need to configure custom forwarding rules.
Annotation	You can enter custom annotation names and values. You can also select or search for annotations by name from the drop-down list. For more information about Ingress annotations, see Annotations. Click +Add Annotation to add an annotation. ACK does not limit the number of Ingress annotations that you can add.	In this example, you do not need to configure annotations.
Label	You can add labels to describe the characteristics of the Ingress. Click +Add Label to add a label. ACK does not limit the number of Ingress labels that you can add.	In this example, you do not need to configure labels.

After the configurations are complete, click OK in the lower-left corner of the Create Ingress panel.
Verify that the Ingress is created.
1. In the left-side pane, choose Network > Ingresses. The Ingress named cafe-ingress is displayed on the Ingresses page.
2. In the Endpoint column of cafe-ingress, view the endpoint.

kubectl

Create a file named cafe-ingress.yaml. Copy and paste the following content to the file. The file is used to create an Ingress.

YAML configuration file

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

The following table describes the parameters that you can specify.

Parameter	Required	Description
metadata.name	Yes	The name of the Ingress. Note The name of an Ingress must be unique in the cluster. Therefore, when you create an Ingress, make sure that the Ingress name is unique to prevent name conflicts.
spec.ingressClassName	Yes	The name of the associated IngressClass.
spec.rules.host	No	The domain name in the HTTP host header. You must set this parameter to a custom domain name. When you access the domain name, such as http://demo.domain.ingress.top, in a browser, the browser automatically adds the Host: demo.domain.ingress.top header when an HTTP request is sent. This way, the server identifies the destination host based on the header. In Kubernetes, the host field in an Ingress rule is used to match the host header in a request. If the host header is matched, the request is sent to the corresponding backend Service. Note If you specify a custom domain name, make sure that the Internet Content Provider (ICP) filing for the domain name is complete. Otherwise, the domain name may fail to be resolved. For more information, see ICP filing application overview. If this parameter is not specified, the Ingress rule matches all requests that are sent to the Ingress controller.
spec.rules.http.paths.path	Yes	The URL path.
spec.rules.http.paths.pathType	Yes	The URL matching rule. For more information, see the Forward requests based on URL paths section of the "Advanced ALB Ingress configurations" topic.
spec.rules.http.paths.backend.service.name	Yes	The name of the Service that you create.
spec.rules.http.paths.backend.service.port.number	Yes	The port number of the Service that you create. The port is important because the port is used to route requests to the backend Service. Make sure that the port is valid to ensure that requests can be routed to the backend Service and processed as expected.

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

Optional. Run the following command to obtain the domain name of the ALB instance:

kubectl get ingress

Expected output:

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

(Optional) Step 6: Configure domain name resolution

If you set the spec.rules.host parameter to a custom domain name when you create the Ingress, you must add a CNAME record to map the domain name to the domain name of the ALB instance. Then, you can access the Services by using the custom domain name.

Log on to the ACK console.
Click the cluster name to go to the cluster details page.
In the left-side pane, choose Network > Ingresses.
In the Endpoint column of cafe-ingress, copy the domain name.

Perform the following steps to create a CNAME record:

Log on to the Alibaba Cloud DNS console.
On the Domain Name Resolution page, click Add Domain Name.
In the Add Domain Name dialog box, enter the domain name of your host and click OK.
Important
Before you create the CNAME record, you must use a TXT record to verify the ownership of the domain name.
Find the domain name that you want to manage and click DNS Settings in the Actions column.
On the DNS Settings page, click Add DNS Record.

In the Add DNS Record panel, configure the following parameters and click OK.

Parameter	Description
Record Type	The type of the DNS record. Select CNAME from the drop-down list.
Hostname	The prefix of the domain name. Example: `www`.
DNS Request Source	The region from which the DNS request is sent. Select Default from the drop-down list.
Value	The CNAME. The CNAME is the domain name that you copied.
TTL	The time-to-live (TTL) of the CNAME record to be cached on the DNS server. In this example, the default value is used.

Step 7: Test traffic forwarding

Enter "test domain name + URL path" in the address bar of a browser to check whether traffic is forwarded to the specified Service.

Note

If you configure a custom domain name, the test domain name is the custom domain name.
If you have not configured a custom domain name, the test domain name is the endpoint of cafe-ingress.

In this example, demo.domain.ingress.top is used.

Enter demo.domain.ingress.top/coffee in the address bar of a browser. The page of the coffee-svc Service appears.
Enter demo.domain.ingress.top/tea in the address bar of a browser. The page of the tea-svc Service appears.

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 forwarding rules, forwarding conditions, and actions, see Customize the routing rules of an ALB Ingress.
For more information about how to use 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 controller troubleshooting and ALB Ingress FAQ.