feat: support third party orm to interact with go-zero (#1286)

* fixes #987

* chore: fix test failure

* chore: add comments

* feat: support third party orm to interact with go-zero

* chore: refactor

zrpc/resolver/internal/kube/targetparser.go

@@ -0,0 +1,47 @@
+package kube
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"google.golang.org/grpc/resolver"
+)
+
+const (
+	colon            = ":"
+	defaultNamespace = "default"
+)
+
+var emptyService Service
+
+// Service represents a service with namespace, name and port.
+type Service struct {
+	Namespace string
+	Name      string
+	Port      int
+}
+
+// ParseTarget parses the resolver.Target.
+func ParseTarget(target resolver.Target) (Service, error) {
+	var service Service
+	service.Namespace = target.Authority
+	if len(service.Namespace) == 0 {
+		service.Namespace = defaultNamespace
+	}
+
+	segs := strings.SplitN(target.Endpoint, colon, 2)
+	if len(segs) < 2 {
+		return emptyService, fmt.Errorf("bad endpoint: %s", target.Endpoint)
+	}
+
+	service.Name = segs[0]
+	port, err := strconv.Atoi(segs[1])
+	if err != nil {
+		return emptyService, err
+	}
+
+	service.Port = port
+
+	return service, nil
+}