Ingresses can use HTTP/2 to expose Services. Connections from the load balancer to your application use HTTP/1.x by default. If your application is capable of receiving HTTP/2 requests, you can add the following field to the ingress annotation to enable the use of HTTP/2:

kubernetes.io/elb.http2-enable: 'true'

An HTTPS-compliant load balancer supports HTTP/2.
This function is available in clusters of version v1.23.13-r0, v1.25.8-r0, v1.27.5-r0, or v1.28.3-r0.
After HTTP/2 is configured, if you delete the advanced configuration for enabling HTTP/2 on the CCE console or delete the target annotation from the YAML file, the configuration on the ELB will be retained.

The following shows an example YAML file where an existing load balancer is associated:

apiVersion: networking.k8s.io/v1
kind: Ingress 
metadata: 
  name: ingress-test
  annotations: 
    kubernetes.io/elb.id: <your_elb_id>  # Replace it with the ID of your existing load balancer.
    kubernetes.io/elb.ip: <your_elb_ip>  # Replace it with the IP of your existing load balancer.
    kubernetes.io/elb.port: '443'
    kubernetes.io/elb.http2-enable: 'true' # Enable HTTP/2.
spec:
  tls: 
  - secretName: ingress-test-secret
  rules: 
  - host: ''
    http: 
      paths: 
      - path: '/'
        backend: 
          service:
            name: <your_service_name>  # Replace it with the name of your target Service.
            port: 
              number: 8080             # Replace 8080 with the port number of your target Service.
        property:
          ingress.beta.kubernetes.io/url-match-mode: STARTS_WITH
        pathType: ImplementationSpecific
  ingressClassName: cce

**Table 1** HTTP/2 parameters
Parameter	Mandatory	Type	Description
kubernetes.io/elb.http2-enable	No	String	Whether HTTP/2 is enabled. Request forwarding using HTTP/2 improves the access performance between your application and the load balancer. However, the load balancer still uses HTTP/1.x to forward requests to the backend server. Options: true: enabled false: disabled (default value) Note: HTTP/2 can be enabled or disabled only when the listener uses HTTPS. This parameter is invalid and defaults to false when the listener protocol is HTTP.

Configuring HTTP/2 for a LoadBalancer Ingress