feat: introduce handshake to client and gRPC server

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/golang/mock v1.6.0
 	github.com/stretchr/testify v1.7.1
 	go.uber.org/automaxprocs v1.5.2
+	golang.org/x/net v0.8.0
 	golang.org/x/sync v0.1.0
 	google.golang.org/grpc v1.54.0
 	google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.2.0
@@ -17,7 +18,6 @@ require (
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/net v0.8.0 // indirect
 	golang.org/x/sys v0.6.0 // indirect
 	golang.org/x/text v0.8.0 // indirect
 	google.golang.org/genproto v0.0.0-20230110181048-76db0878b65f // indirect

pkg/function/client/client.go

@@ -3,19 +3,21 @@ package client
 import (
 	"context"
 	"fmt"
+	"io"
+	"log"
+	"os"
+	"runtime"
+	"strconv"
+
 	functionpb "github.com/numaproj/numaflow-go/pkg/apis/proto/function/v1"
 	"github.com/numaproj/numaflow-go/pkg/function"
+	"github.com/numaproj/numaflow-go/pkg/info"
 	_ "go.uber.org/automaxprocs"
 	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/protobuf/types/known/emptypb"
-	"io"
-	"log"
-	"os"
-	"runtime"
-	"strconv"
 )
 
 // client contains the grpc connection and the grpc client.
@@ -26,14 +28,14 @@ type client struct {
 
 // New creates a new client object.
 func New(inputOptions ...Option) (*client, error) {
-
 	var opts = &options{
-		maxMessageSize: function.DefaultMaxMessageSize,
+		maxMessageSize:      function.DefaultMaxMessageSize,
+		sereverInfoFilePath: info.ServerInfoFilePath,
 	}
 
 	// Populate connection variables for client connection
 	// based on multiprocessing enabled/disabled
-	if function.IsMapMultiProcEnabled() == true {
+	if function.IsMapMultiProcEnabled() {
 		regMultProcResolver()
 		opts.sockAddr = function.TCP_ADDR
 	} else {
@@ -44,12 +46,22 @@ func New(inputOptions ...Option) (*client, error) {
 		inputOption(opts)
 	}
 
+	// TODO: WaitUntilReady() check unitl SIGTERM is received.
+	serverInfo, err := info.Read(info.WithServerInfoFilePath(opts.sereverInfoFilePath))
+	if err != nil {
+		// TODO: return nil, err
+		log.Println("Failed to execute info.Read(): ", err)
+	}
+	// TODO: Use serverInfo to check compatibility and start the right gRPC client.
+	if serverInfo != nil {
+		log.Printf("ServerInfo: %v\n", serverInfo)
+	}
+
 	c := new(client)
 	var conn *grpc.ClientConn
-	var err error
 	var sockAddr string
 	// Make a TCP connection client for multiprocessing grpc server
-	if function.IsMapMultiProcEnabled() == true {
+	if function.IsMapMultiProcEnabled() {
 		log.Println("Multiprocessing TCP Client ", function.TCP, opts.sockAddr)
 		sockAddr = fmt.Sprintf("%s%s", connAddr, opts.sockAddr)
 		conn, err = grpc.Dial(

pkg/function/client/options.go

@@ -1,8 +1,9 @@
 package client
 
 type options struct {
-	sockAddr       string
-	maxMessageSize int
+	sockAddr            string
+	maxMessageSize      int
+	sereverInfoFilePath string
 }
 
 // Option is the interface to apply options.
@@ -21,3 +22,10 @@ func WithMaxMessageSize(size int) Option {
 		opts.maxMessageSize = size
 	}
 }
+
+// WithServerInfoFilePath sets the server info file path to the given path.
+func WithServerInfoFilePath(f string) Option {
+	return func(o *options) {
+		o.sereverInfoFilePath = f
+	}
+}

pkg/function/server/options.go

@@ -1,8 +1,9 @@
 package server
 
 type options struct {
-	sockAddr       string
-	maxMessageSize int
+	sockAddr            string
+	maxMessageSize      int
+	sereverInfoFilePath string
 }
 
 // Option is the interface to apply options.
@@ -21,3 +22,10 @@ func WithSockAddr(addr string) Option {
 		opts.sockAddr = addr
 	}
 }
+
+// WithServerInfoFilePath sets the server info file path to the given path.
+func WithServerInfoFilePath(f string) Option {
+	return func(opts *options) {
+		opts.sereverInfoFilePath = f
+	}
+}

pkg/function/server/server.go

@@ -11,6 +11,7 @@ import (
 
 	functionpb "github.com/numaproj/numaflow-go/pkg/apis/proto/function/v1"
 	functionsdk "github.com/numaproj/numaflow-go/pkg/function"
+	"github.com/numaproj/numaflow-go/pkg/info"
 	"google.golang.org/grpc"
 )
 
@@ -83,14 +84,21 @@ func (s *server) RegisterReducer(r functionsdk.ReduceHandler) *server {
 // Start starts the gRPC server via unix domain socket at configs.Addr and return error.
 func (s *server) Start(ctx context.Context, inputOptions ...Option) error {
 	var opts = &options{
-		sockAddr:       functionsdk.UDS_ADDR,
-		maxMessageSize: functionsdk.DefaultMaxMessageSize,
+		sockAddr:            functionsdk.UDS_ADDR,
+		maxMessageSize:      functionsdk.DefaultMaxMessageSize,
+		sereverInfoFilePath: info.ServerInfoFilePath,
 	}
 
 	for _, inputOption := range inputOptions {
 		inputOption(opts)
 	}
 
+	// Write server info to the file
+	serverInfo := &info.ServerInfo{Protocol: info.UDS, Language: info.Go, Version: info.GetSDKVersion()}
+	if err := info.Write(serverInfo, info.WithServerInfoFilePath(opts.sereverInfoFilePath)); err != nil {
+		return err
+	}
+
 	cleanup := func() error {
 		// err if no opts.sockAddr should be ignored
 		if _, err := os.Stat(opts.sockAddr); err == nil {
@@ -109,6 +117,7 @@ func (s *server) Start(ctx context.Context, inputOptions ...Option) error {
 	if err != nil {
 		return fmt.Errorf("failed to execute net.Listen(%q, %q): %v", functionsdk.UDS, functionsdk.UDS_ADDR, err)
 	}
+	defer func() { _ = lis.Close() }()
 	grpcServer := grpc.NewServer(
 		grpc.MaxRecvMsgSize(opts.maxMessageSize),
 		grpc.MaxSendMsgSize(opts.maxMessageSize),

pkg/function/server/server_test.go

@@ -3,13 +3,14 @@ package server
 import (
 	"context"
 	"fmt"
-	"google.golang.org/protobuf/types/known/emptypb"
 	"os"
 	"strconv"
 	"sync"
 	"testing"
 	"time"
 
+	"google.golang.org/protobuf/types/known/emptypb"
+
 	"github.com/stretchr/testify/assert"
 	grpcmd "google.golang.org/grpc/metadata"
 	"google.golang.org/protobuf/types/known/timestamppb"
@@ -41,12 +42,21 @@ type fields struct {
 }
 
 func Test_server_map(t *testing.T) {
-	file, err := os.CreateTemp("/tmp", "numaflow-test.sock")
+	socketFile, err := os.CreateTemp("/tmp", "numaflow-test.sock")
 	assert.NoError(t, err)
 	defer func() {
-		err = os.RemoveAll(file.Name())
+		err = os.RemoveAll(socketFile.Name())
+		assert.NoError(t, err)
+	}()
+
+	serverInfoFile, err := os.CreateTemp("/tmp", "numaflow-test-info")
+	fmt.Println(serverInfoFile.Name())
+	assert.NoError(t, err)
+	defer func() {
+		err = os.RemoveAll(serverInfoFile.Name())
 		assert.NoError(t, err)
 	}()
+
 	tests := []struct {
 		name   string
 		fields fields
@@ -66,14 +76,15 @@ func Test_server_map(t *testing.T) {
 			// note: using actual UDS connection
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 			defer cancel()
-			go New().RegisterMapper(tt.fields.mapHandler).Start(ctx, WithSockAddr(file.Name()))
-			c, err := client.New(client.WithSockAddr(file.Name()))
+			go New().RegisterMapper(tt.fields.mapHandler).Start(ctx, WithSockAddr(socketFile.Name()), WithServerInfoFilePath(serverInfoFile.Name()))
+			c, err := client.New(client.WithSockAddr(socketFile.Name()), client.WithServerInfoFilePath(serverInfoFile.Name()))
 			waitUntilReady(ctx, c, t)
 			assert.NoError(t, err)
 			defer func() {
 				err = c.CloseConn(ctx)
 				assert.NoError(t, err)
 			}()
+
 			for i := 0; i < 10; i++ {
 				keys := []string{fmt.Sprintf("client_%d", i)}
 				list, err := c.MapFn(ctx, &functionpb.Datum{
@@ -95,12 +106,20 @@ func Test_server_map(t *testing.T) {
 }
 
 func Test_server_mapT(t *testing.T) {
-	file, err := os.CreateTemp("/tmp", "numaflow-test.sock")
+	socketFile, err := os.CreateTemp("/tmp", "numaflow-test.sock")
 	assert.NoError(t, err)
 	defer func() {
-		err = os.RemoveAll(file.Name())
+		err = os.RemoveAll(socketFile.Name())
 		assert.NoError(t, err)
 	}()
+
+	serverInfoFile, err := os.CreateTemp("/tmp", "numaflow-test-info")
+	assert.NoError(t, err)
+	defer func() {
+		err = os.RemoveAll(serverInfoFile.Name())
+		assert.NoError(t, err)
+	}()
+
 	tests := []struct {
 		name   string
 		fields fields
@@ -120,8 +139,8 @@ func Test_server_mapT(t *testing.T) {
 			// note: using actual UDS connection
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 			defer cancel()
-			go New().RegisterMapperT(tt.fields.mapTHandler).Start(ctx, WithSockAddr(file.Name()))
-			c, err := client.New(client.WithSockAddr(file.Name()))
+			go New().RegisterMapperT(tt.fields.mapTHandler).Start(ctx, WithSockAddr(socketFile.Name()), WithServerInfoFilePath(serverInfoFile.Name()))
+			c, err := client.New(client.WithSockAddr(socketFile.Name()), client.WithServerInfoFilePath(serverInfoFile.Name()))
 			waitUntilReady(ctx, c, t)
 			assert.NoError(t, err)
 			defer func() {
@@ -155,6 +174,14 @@ func Test_server_reduce(t *testing.T) {
 		err = os.RemoveAll(file.Name())
 		assert.NoError(t, err)
 	}()
+
+	serverInfoFile, err := os.CreateTemp("/tmp", "numaflow-test-info")
+	assert.NoError(t, err)
+	defer func() {
+		err = os.RemoveAll(serverInfoFile.Name())
+		assert.NoError(t, err)
+	}()
+
 	var testKeys = []string{"reduce_key"}
 	tests := []struct {
 		name   string
@@ -197,9 +224,9 @@ func Test_server_reduce(t *testing.T) {
 			// note: using actual UDS connection
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 			defer cancel()
-			go New().RegisterReducer(tt.fields.reduceHandler).Start(ctx, WithSockAddr(file.Name()))
+			go New().RegisterReducer(tt.fields.reduceHandler).Start(ctx, WithSockAddr(file.Name()), WithServerInfoFilePath(serverInfoFile.Name()))
 
-			c, err := client.New(client.WithSockAddr(file.Name()))
+			c, err := client.New(client.WithSockAddr(file.Name()), client.WithServerInfoFilePath(serverInfoFile.Name()))
 			waitUntilReady(ctx, c, t)
 			assert.NoError(t, err)
 			defer func() {
@@ -228,9 +255,7 @@ func Test_server_reduce(t *testing.T) {
 			wg.Add(1)
 			go func() {
 				defer wg.Done()
-				for _, d := range resultDatumList {
-					dList.Elements = append(dList.Elements, d)
-				}
+				dList.Elements = append(dList.Elements, resultDatumList...)
 			}()
 
 			wg.Wait()

pkg/info/doc.go

@@ -0,0 +1,19 @@
+// Package info is used for the gRPC server to provide the information such as protocol, sdk version, language, etc, to the client.
+//
+// The server information can be used by the client to determine:
+//   - what is right protocol to use (UDS or TCP)
+//   - what is the numaflow sdk version used by the server
+//   - what is language used by the server
+//
+// The gRPC server (UDF, UDSink, etc) is supposed to have a shared file system with the client (numa container).
+//
+// Write()
+// The gPRC server must use this function to write the correct ServerInfo when it starts.
+//
+// Read()
+// The client is supposed to call the function to read the server information, before it starts to communicate with the gRPC server.
+//
+// WaitUntilReady()
+// This function checks if the server info file is ready to read.
+// The client (numa container) is supposed to call the function before it starts to Read() the server info file.
+package info

pkg/info/options.go

@@ -0,0 +1,20 @@
+package info
+
+type options struct {
+	svrInfoFilePath string
+}
+
+func defaultOptions() *options {
+	return &options{
+		svrInfoFilePath: ServerInfoFilePath,
+	}
+}
+
+type Option func(*options)
+
+// WithServerInfoFilePath sets the server info file path
+func WithServerInfoFilePath(f string) Option {
+	return func(o *options) {
+		o.svrInfoFilePath = f
+	}
+}