Configuring a Slow Start for a LoadBalancer Ingress

Prerequisites

• You have created a cluster whose version is v1.23 or later.
• The cluster can be accessed using kubectl. For details, see Connecting to a Cluster Using kubectl.

Notes and Constraints

• Only dedicated load balancers support slow start for HTTP and HTTPS backend server groups.
• Slow start takes effect only when the weighted round robin algorithm is used.
• Slow start takes effect only for new backend server pods.
• After the slow start duration elapses, backend servers will not enter the slow start mode again.
• Slow start takes effect when health check is enabled and backend server pods are running properly.
• If health check is disabled, slow start takes effect immediately.
• With slow start configured for an ingress, all forwarding policies of the ingress take effect.

Procedure

1. Use kubectl to access the cluster. For details, see Connecting to a Cluster Using kubectl.
2. Create a YAML file named ingress-test.yaml. The file name can be customized.

   vi ingress-test.yaml

   An example YAML file of an ingress associated with an existing load balancer is as follows:

   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: ingress-test
     namespace: default
     annotations:
       kubernetes.io/elb.port: '80'
       kubernetes.io/elb.id: <your_elb_id>  # Replace it with the ID of your existing load balancer.
       kubernetes.io/elb.class: performance
       kubernetes.io/elb.slowstart: '30' #Configure a slow start.
   spec:
     rules:
       - host: ''
         http:
           paths:
             - path: /
               backend:
                 service:
                   name: <your_service_name>  # Replace it with the name of your target Service.
                   port:
                     number: 80             # Replace 80 with the port number of your target Service.
               property:
                 ingress.beta.kubernetes.io/url-match-mode: STARTS_WITH
               pathType: ImplementationSpecific
     ingressClassName: cce

   Table 1 Parameters for configuring a slow start

   Parameter	Mandatory	Type	Description
   kubernetes.io/elb.slowstart	No	String	Specifies whether to enable slow start. After you enable it, the load balancer linearly increases the proportion of requests to backend server pods in this mode. When the slow start duration elapses, the load balancer sends full share of requests to backend server pods and exits the slow start mode. Clusters later than v1.23 support this field. The slow start duration ranges from 30 to 1200. Duration of slow start, in seconds. Grayscale release applies only to dedicated load balancers. This parameter is valid only when the allocation policy of the target Service is weighted round robin (WRR) and sticky session is disabled.

3. Create an ingress.

   kubectl create -f ingress-test.yaml

   If information similar to the following is displayed, the ingress has been created:

   ingress/ingress-test created

4. Check the created ingress.

   kubectl get ingress

   If information similar to the following is displayed, the ingress has been created:

   NAME          CLASS    HOSTS     ADDRESS          PORTS   AGE
   ingress-test  cce      *         121.**.**.**     80      10s