api/resolver: update resolver to enable subdomain routing (#1747)

* api/resolver: update domain / service prefix usage

* api/resolver/subdomain: implement subdomain resolver for domain resolution

* api/handler: fix tests

api/resolver/options.go

@@ -1,23 +1,17 @@
 package resolver
 
 import (
-	"net/http"
+	"github.com/micro/go-micro/v2/registry"
 )
 
-// NewOptions returns new initialised options
-func NewOptions(opts ...Option) Options {
-	var options Options
-	for _, o := range opts {
-		o(&options)
-	}
-
-	if options.Namespace == nil {
-		options.Namespace = StaticNamespace("go.micro")
-	}
-
-	return options
+type Options struct {
+	Handler       string
+	Domain     string
+	ServicePrefix string
 }
 
+type Option func(o *Options)
+
 // WithHandler sets the handler being used
 func WithHandler(h string) Option {
 	return func(o *Options) {
@@ -25,9 +19,29 @@ func WithHandler(h string) Option {
 	}
 }
 
-// WithNamespace sets the function which determines the namespace for a request
-func WithNamespace(n func(*http.Request) string) Option {
+// WithDomain sets the namespace option
+func WithDomain(n string) Option {
 	return func(o *Options) {
-		o.Namespace = n
+		o.Domain = n
 	}
 }
+
+// WithServicePrefix sets the ServicePrefix option
+func WithServicePrefix(p string) Option {
+	return func(o *Options) {
+		o.ServicePrefix = p
+	}
+}
+
+// NewOptions returns new initialised options
+func NewOptions(opts ...Option) Options {
+	var options Options
+	for _, o := range opts {
+		o(&options)
+	}
+	if len(options.Domain) == 0 {
+		options.Domain = registry.DefaultDomain
+	}
+
+	return options
+}