Use Ingress to provide Layer-7 service access - User Guide for Serverless Kubernetes Clusters| Alibaba Cloud Documentation Center

Use Ingress to provide Layer-7 service access

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Last Updated: Aug 14, 2019 Edit in Github

In the Alibaba Cloud serverless Kubernetes cluster, Server Load Balancer provides Layer-4 service access. You can also use Layer-7 service access provided by Ingress. This document describes how to provide Layer-7 domain name service access in the serverless Kubernetes cluster.

Prerequisites

You have created a Serverless cluster. VPC cluster must be configured with a NAT gateway to access the external network and download the container image.
You have connected to the cluster by using kubectl, see Connect to a Kubernetes cluster by using kubectl.

Instructions

If Server Load Balancer is not specified, system automatically generates a public network Server Load Balancer instance.
The default front-end listening ports for SLB instances are 80 (HTTP Protocol) and 443 (HTTPS protocol ).
By default, the HTTPS certificate of the SLB instance is initialized for the first created Ingress-configured TLS certificate. Otherwise, the system default certificate is initialized. You can modify it in the SLB console as needed.
When you specify to use an existing SLB instance, SLB instance specification must be of performance guarantee type (supports ENI). Also, make sure that ports 80 and 443 are not currently used by other services.

Use the default generated SLB instance

If an SLB instance is not specified, the system automatically generates a performance guaranteed public network SLB instance when the first Ingress is created.

Deploy test services.

Create a file cafe-service.yaml, copy the following code to the file, and then run the kubectl apply -f cafe-service.yaml command to deploy a coffee service and tea service.

apiVersion: extensions/v1beta1
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: extensions/v1beta1
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

The following outputs indicate the services are deployed:

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

Run the kubectl get svc,deploy command to view the status of the services.

NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
svc/coffee-svc   ClusterIP   <none>       <none>        80/TCP    1m
svc/tea-svc      ClusterIP   <none>       <none>        80/TCP    1m

NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/coffee   2         2         2            2           1m
deploy/tea      1         1         1            1           1m

Configure an Ingress.

Create a file cafe-ingress.yaml, copy the following code into the file, and run the kubectl apply -f cafe-ingress.yaml command.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: cafe-ingress
spec:
  rules:
  # Set a Layer-7 domain name.
  - host: foo.bar.com
    http:
      paths:
      # Set the context path.
      - path: /tea
        backend:
          serviceName: tea-svc
          servicePort: 80
      # Set the context path.
      - path: /coffee
        backend:
          serviceName: coffee-svc
          servicePort: 80

The following output indicates that the Ingress is deployed.

ingress "cafe-ingress" created

Run the kubectl get ing command to obtain the IP address of the SLB instance.

NAME           HOSTS         ADDRESS          PORTS     AGE
cafe-ingress   foo.bar.com   139.***.**.***   80        1m

Test service access.

Note The domain name of the SLB instance IP must be resolved manually.
In this example, a DNS domain name resolution rule is added to hosts for testing service access. We recommend that you enter the domain name in your work environment.
```
139.***.**.***    foo.bar.com
```
- Use your browser to access the coffee service.
- Run the following command to access the coffee service:
```
curl -H "Host: foo.bar.com" http://139.***.**.***/coffee
```
- Use your browser to access the coffee service.
- Run the following command to access the tea service:
```
curl -H "Host: foo.bar.com" http://139.***.**.***/tea
```

Use the specified SLB instance

You can specify to use of an existing SLB instance by using the service.beta.kubernetes.io/alicloud-loadbalancer-id annotation, but the SLB instance specification must be of performance guarantee type (supports ENI).

Note System automatically initializes ports 80 and 443 of the SLB instance, make sure that ports are not currently used by other services.

Deploy test services.

Create a file tomcat-service.yml, copy the following code into the file, and run the kubectl apply -f tomcat-service.yml command to deploy a Tomcat application.

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: tomcat
spec:
  replicas: 1
  selector:
    matchLabels:
      run: tomcat
  template:
    metadata:
      labels:
        run: tomcat
    spec:
      containers:
      - image: tomcat:7.0
        imagePullPolicy: Always
        name: tomcat
        ports:
        - containerPort: 8080
          protocol: TCP
      restartPolicy: Always
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat
spec:
  ports:
  - port: 8080
    protocol: TCP
    targetPort: 8080
  selector:
    run: tomcat
  clusterIP: None

The following outputs indicates the Tomcat application is deployed:

deployment "tomcat" created
service "tomcat" created

Run the kubectl get svc,deploy tomcat command to view the application status.

NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
svc/tomcat   ClusterIP   <none>       <none>        8080/TCP   1m

NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/tomcat   1         1         1            1           1m

Apply for an SLB instance.
You must apply for a performance guarantee type SLB instance (such as slb.s2.small) under the cluster and region. According to the specific needs, private or public network can be used. For more information, see Create an SLB instance. In this example, apply for an Internet SLB instance and record the ID of the SLB instance.
Configure an TLS certificate.
You must configure the TLS certificate for HTTPS access.
1. Run the following commands to generate an TLS certificate:
```
$ openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=bar.foo.com/O=bar.foo.com"
$ kubectl create secret tls cert-example --key tls.key --cert tls.crt

secret "cert-example" created
```
2. Run the following command to view the created TLS certificate:
```
$ kubectl get secret cert-example

NAME           TYPE                DATA      AGE
cert-example   kubernetes.io/tls   2         12s
```
Note System automatically initializes the SLB HTTPS default certificate according to the first created Ingress TLS certificate. If you want to modify the HTTPS default certificate, you can modify it in the SLB console. If you want to configure multiple certificates, you can manually add them in the SLB console HTTPS listener domain name extension.

Configure an Ingress.

Create a file tomcat-ingress.yml, copy the following command to the file, and run the kubectl apply -f tomcat-ingress.yml command.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: tomcat-ingress
  annotations:
    # Specify an SLB instance.
    service.beta.kubernetes.io/alicloud-loadbalancer-id: lb-xxxxxxxxxx            ##Set the ID of the target SLB instance.
    service.beta.kubernetes.io/alicloud-loadbalancer-force-override-listeners: "true"
spec:
  tls:
  - hosts:
    - bar.foo.com
    # Set a TLS certificate.
    secretName: cert-example
  rules:
  # Set a Layer-7 domain name.
  - host: bar.foo.com
    http:
      paths:
      # Set the context path.
      - path: /
        backend:
          serviceName: tomcat
          servicePort: 8080

The following output indicates the tomcat-ingress is deployed:

ingress "tomcat-ingress" created

Run the kubectl get ing tomcat-ingress command to obtain the IP address of the SLB instance.

NAME             HOSTS         ADDRESS        PORTS     AGE
tomcat-ingress   bar.foo.com   47.***.**.**   80, 443   1m

Test service access.

Note Currently, the domain name of the SLB instance IP must be resolved manually.
In this example, a DNS domain name resolution rule is added to hosts for testing service access. We recommend that you enter the domain name in your work environment.
```
47.***.**.**   bar.foo.com
```
- Use you browser to access the Tomcat service.
- Run the following command to access the Tomcat service:
```
curl -k -H "Host: bar.foo.com" https://47.***.**.**
```