service: add react web app serving option

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

service/options.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
+	"embed"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -352,6 +353,17 @@ func WithGatewayOpts(opts ...runtime.ServeMuxOption) Option {
 	}
 }
 
+// WithReactUI add static single page app serving to the http server
+// subpath is the path in the read-only file embed.FS to use as root to serve
+// static content
+func WithReactUI(fs embed.FS, subpath string) Option {
+	return func(o *options) {
+		o.reactUI = fs
+		o.reactUISubPath = subpath
+		o.hasReactUI = true
+	}
+}
+
 type options struct {
 	ctx     context.Context
 	name    string
@@ -394,6 +406,10 @@ type options struct {
 	gatewayOpts   []runtime.ServeMuxOption
 	cors          cors.Options
 
+	reactUI        embed.FS
+	reactUISubPath string
+	hasReactUI     bool
+
 	error         error
 	gatewayPrefix string
 }

service/service.go

@@ -133,6 +133,9 @@ func newService(opts ...Option) (*service, error) {
 	if err := s.gateway(s.opts.gatewayOpts...); err != nil {
 		return nil, err
 	}
+	if err := s.reactApp(); err != nil {
+		return nil, err
+	}
 	// we do not configure grpc web here as the grpc handlers are not yet registered
 	return s, nil
 }
@@ -203,7 +206,7 @@ func (s *service) run() error {
 	hServer := &http.Server{
 		Handler: alice.New(s.opts.middlewares...).Then(cors.New(s.opts.cors).Handler(s.opts.mux)),
 	}
-	if s.opts.Gateway() || s.opts.grpcWeb {
+	if s.opts.Gateway() || s.opts.grpcWeb || s.opts.hasReactUI {
 		go func() {
 			errs <- hServer.Serve(hList)
 			hServer.Shutdown(s.opts.ctx)

service/web.go

@@ -5,6 +5,8 @@ import (
 	"time"
 
 	"github.com/improbable-eng/grpc-web/go/grpcweb"
+
+	"go.linka.cloud/grpc/react"
 )
 
 var defaultWebOptions = []grpcweb.Option{
@@ -33,3 +35,15 @@ func (s *service) grpcWeb(opts ...grpcweb.Option) error {
 	}
 	return nil
 }
+
+func (s *service) reactApp() error {
+	if !s.opts.hasReactUI {
+		return nil
+	}
+	h, err := react.NewHandler(s.opts.reactUI, s.opts.reactUISubPath)
+	if err != nil {
+		return err
+	}
+	s.opts.mux.Handle("/", h)
+	return nil
+}