feat: support build tag to reduce binary size w/o k8s (#4323)

zrpc/resolver/internal/kubebuilder.go

@@ -1,3 +1,5 @@
+//go:build !no_k8s
+
 package internal
 
 import (

zrpc/resolver/internal/register.go

@@ -0,0 +1,8 @@
+//go:build no_k8s
+
+package internal
+
+// RegisterResolver registers the direct, etcd and discov schemes to the resolver.
+func RegisterResolver() {
+	register()
+}

zrpc/resolver/internal/register_k8s.go

@@ -0,0 +1,13 @@
+//go:build !no_k8s
+
+package internal
+
+import "google.golang.org/grpc/resolver"
+
+var k8sResolverBuilder kubeBuilder
+
+// RegisterResolver registers the direct, etcd, discov and k8s schemes to the resolver.
+func RegisterResolver() {
+	register()
+	resolver.Register(&k8sResolverBuilder)
+}

zrpc/resolver/internal/resolver.go

@@ -28,15 +28,12 @@ var (
 	directResolverBuilder directBuilder
 	discovResolverBuilder discovBuilder
 	etcdResolverBuilder   etcdBuilder
-	k8sResolverBuilder    kubeBuilder
 )
 
-// RegisterResolver registers the direct and discov schemes to the resolver.
-func RegisterResolver() {
+func register() {
 	resolver.Register(&directResolverBuilder)
 	resolver.Register(&discovResolverBuilder)
 	resolver.Register(&etcdResolverBuilder)
-	resolver.Register(&k8sResolverBuilder)
 }
 
 type nopResolver struct {