[Bug] Service (Serve) changing port from 8000 to 9000 doesn't work

[kevin85421]

Why are these changes needed?

Without this PR, users can only serve requests via port 8000.

To serve requests via another port (e.g. 9000), user needs to specify spec.serveConfig.port and the head Pod's serve port to 9000. See RESTful API and single-application config schema for more details.

The HTTPProxy is used to check the health condition (code) of Serve deployments. If the Serve deployments are healthy, the HTTPProxy will add the label "ray.io/serve=true" to the Pod. Note that the selector of Kubernetes Serve service also includes "ray.io/serve=true". That is, the traffic will be redirected to the Serve deployments after HTTPProxy believes that the deployments are healthy.

Others

• Convert HealthCheckPath (public) into healthCheckPath (private) because the variable is only used by the function CheckHealth().

• The single-application config schema indicates that port is an int in Python. However, the size of int type in Python depends on the underlying platform and implementation. Hence, I am unsure about which integer type to use in Golang (e.g. int, int32, int64). I conducted the following experiment and found that there is no difference between int, int32, and int64 after serializing. Hence, I declare Port as an int in this PR.

  package main
  
  import (
      "bytes"
      "encoding/json"
      "fmt"
  )
  
  func main() {
      // Define sample integer values
      valueInt := 42
      valueInt32 := int32(42)
      valueInt64 := int64(42)
  
      // Serialize int to JSON
      jsonInt, _ := json.Marshal(valueInt)
      fmt.Println("Serialized int:", jsonInt, string(jsonInt))
  
      // Serialize int32 to JSON
      jsonInt32, _ := json.Marshal(valueInt32)
      fmt.Println("Serialized int32:", jsonInt32, string(jsonInt32))
  
      // Serialize int64 to JSON
      jsonInt64, _ := json.Marshal(valueInt64)
      fmt.Println("Serialized int64:", jsonInt64, string(jsonInt64))
  
      // Compare the byte slices
      equal := bytes.Equal(jsonInt, jsonInt32) && bytes.Equal(jsonInt32, jsonInt64)
      fmt.Println("Are the byte slices equal?", equal)
  }
  
  # STDOUT
  Serialized int: [52 50] 42
  Serialized int32: [52 50] 42
  Serialized int64: [52 50] 42
  Are the byte slices equal? true

Related issue number

Closes #570

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

# Step 0: Build the KubeRay operator
# Step 1: Install the KubeRay operator. Note that we need to use the local Helm chart because this PR includes CRD 
changes.
# (path: helm-chart/kuberay-operator)
helm install kuberay-operator . --set image.repository=controller,image.tag=latest

# Step 2: Create a RayService (path: ray-operator/config/samples)
kubectl apply -f ray-service.different-port.yaml

# Step 3: Wait until the service `rayservice-sample-serve-svc` is created and forward the port 9000
kubectl port-forward svc/rayservice-sample-serve-svc 9000

# Step 4: Test it
curl -X POST -H 'Content-Type: application/json' localhost:9000 -d '["PEAR", 12]'

[kevin85421]

cc @Yicheng-Lu-llll

[Yicheng-Lu-llll]

LGTM!