Configuring Health Check on Multiple Ports of a LoadBalancer Service

The annotation field related to the health check of the LoadBalancer Service is upgraded from Kubernetes.io/elb.health-check-option to Kubernetes.io/elb.health-check-options. Each Service port can be configured separately, and you can configure only some ports. If the port protocol does not need to be configured separately, the original annotation field is still available and does not need to be modified.

Notes and Constraints

This feature is available in the following versions:
- v1.19: v1.19.16-r5 or later
- v1.21: v1.21.8-r0 or later
- v1.23: v1.23.6-r0 or later
- v1.25: v1.25.2-r0 or later
- Versions later than v1.25
Either kubernetes.io/elb.health-check-option or kubernetes.io/elb.health-check-options can be configured.
The target_service_port field is mandatory and must be unique.
For a TCP port, the health check protocol can only be TCP or HTTP. For a UDP port, the health check protocol must be UDP.

Procedure

The following is an example of using the kubernetes.io/elb.health-check-options annotation:

apiVersion: v1
kind: Service
metadata:
  name: nginx
  namespace: default
  labels: 
    app: nginx
    version: v1
  annotations:
    kubernetes.io/elb.class: union         # Load balancer type
    kubernetes.io/elb.id: <your_elb_id>    # Load balancer ID. Replace it with the actual value.
    kubernetes.io/elb.lb-algorithm: ROUND_ROBIN  # Load balancer algorithm
    kubernetes.io/elb.health-check-flag: 'on'    # Enable ELB health check.
    kubernetes.io/elb.health-check-options: '[
	{
		"protocol": "TCP",
		"delay": "5",
		"timeout": "10",
		"max_retries": "3",
		"target_service_port": "TCP:1",
		"monitor_port": "22"
	},
	{
		"protocol": "HTTP",
		"delay": "5",
		"timeout": "10",
		"max_retries": "3",
		"path": "/",
		"target_service_port": "TCP:2",
		"monitor_port": "22",
                "expected_codes": "200-399,401,404"
	}
    ]'
spec:
  selector:
    app: nginx
    version: v1
  externalTrafficPolicy: Cluster
  ports:
    - name: cce-service-0
      targetPort: 1
      nodePort: 0
      port: 1
      protocol: TCP
    - name: cce-service-1
      targetPort: 2
      nodePort: 0
      port: 2
      protocol: TCP
  type: LoadBalancer
  loadBalancerIP: **.**.**.**

**Table 1** elb.health-check-options
Parameter	Mandatory	Type	Description
target_service_port	Yes	String	Port for health check specified by spec.ports. The value consists of the protocol and port number, for example, TCP:80.
monitor_port	No	String	Re-specified port for health check. If this parameter is not specified, the service port is used by default. NOTE: Ensure that the port is in the listening state on the node where the pod is located. Otherwise, the health check result will be affected.
delay	No	String	Health check interval (s) Value range: 1 to 50. Default value: 5
timeout	No	String	Health check timeout, in seconds. Value range: 1 to 50. Default value: 10
max_retries	No	String	Maximum number of health check retries. Value range: 1 to 10. Default value: 3
protocol	No	String	Health check protocol. Default value: protocol of the associated Service Value options: TCP, UDP, or HTTP
path	No	String	Health check URL. This parameter needs to be configured when the protocol is HTTP. Default value: / Value range: 1-80 characters