feat: set zbctl user agent

In order to distinguish between go-client and zbctl add a new possibility to set the UserAgent as client config.
Zbctl use that config and set their own user agent header.

This is useful to understand which client types and versions are mostly used.

(cherry picked from commit 329884a)

clients/go/cmd/zbctl/internal/commands/root.go

@@ -131,6 +131,7 @@ var initClient = func(cmd *cobra.Command, args []string) error {
 	client, err = zbc.NewClient(&zbc.ClientConfig{
 		GatewayAddress:      fmt.Sprintf("%s:%s", host, port),
 		CredentialsProvider: credsProvider,
+		UserAgent:           "zeebe-client-zbctl/" + Version,
 	})
 	return err
 }

clients/go/pkg/zbc/client.go

@@ -65,7 +65,10 @@ type ClientConfig struct {
 	// of 45 seconds being used
 	KeepAlive time.Duration
 
-	DialOpts []grpc.DialOption
+	// UserAgent is an optional field, to specify the user-agent header which should be sent by each
+	// gRPC request. Defaults to zeebe-client-go/%version.
+	UserAgent string
+	DialOpts  []grpc.DialOption
 }
 
 // ErrFileNotFound is returned whenever a file can't be found at the provided path. Use this value to do error comparison.
@@ -158,7 +161,11 @@ func NewClient(config *ClientConfig) (Client, error) {
 		return nil, err
 	}
 
-	config.DialOpts = append(config.DialOpts, grpc.WithUserAgent("zeebe-client-go/"+getVersion()))
+	if config.UserAgent == "" {
+		config.UserAgent = "zeebe-client-go/" + getVersion()
+	}
+
+	config.DialOpts = append(config.DialOpts, grpc.WithUserAgent(config.UserAgent))
 
 	conn, err := grpc.Dial(config.GatewayAddress, config.DialOpts...)
 	if err != nil {

clients/go/pkg/zbc/client_test.go

@@ -18,6 +18,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"github.com/camunda/zeebe/clients/go/v8/internal/utils"
+	"google.golang.org/grpc/metadata"
 	"net"
 	"strconv"
 	"strings"
@@ -164,6 +166,61 @@ func (s *clientTestSuite) TestGatewayAddressEnvVar() {
 	s.EqualValues(fmt.Sprintf("0.0.0.0:%s", parts[len(parts)-1]), config.GatewayAddress)
 }
 
+func (s *clientTestSuite) TestDefaultUserAgent() {
+	// given
+	var incomingContext = make(map[string][]string)
+	lis, server := createServerWithUnaryInterceptor(func(ctx context.Context, _ interface{}, _ *grpc.UnaryServerInfo, _ grpc.UnaryHandler) (interface{}, error) {
+		incomingContext, _ = metadata.FromIncomingContext(ctx)
+		return nil, nil
+	})
+	go server.Serve(lis)
+	defer server.Stop()
+
+	// when
+	client, err := NewClient(&ClientConfig{
+		GatewayAddress:         lis.Addr().String(),
+		UsePlaintextConnection: true,
+	})
+	s.Require().NoError(err)
+	ctx, cancel := context.WithTimeout(context.Background(), utils.DefaultTestTimeout)
+	defer cancel()
+
+	_, err = client.NewTopologyCommand().Send(ctx)
+	userAgent := incomingContext["user-agent"]
+
+	// then
+	s.Require().Len(userAgent, 1)
+	s.Require().Contains(userAgent[0], "zeebe-client-go/"+getVersion())
+}
+
+func (s *clientTestSuite) TestSpecificUserAgent() {
+	// given
+	var incomingContext = make(map[string][]string)
+	lis, server := createServerWithUnaryInterceptor(func(ctx context.Context, _ interface{}, _ *grpc.UnaryServerInfo, _ grpc.UnaryHandler) (interface{}, error) {
+		incomingContext, _ = metadata.FromIncomingContext(ctx)
+		return nil, nil
+	})
+	go server.Serve(lis)
+	defer server.Stop()
+
+	// when
+	client, err := NewClient(&ClientConfig{
+		GatewayAddress:         lis.Addr().String(),
+		UsePlaintextConnection: true,
+		UserAgent:              "anotherUserAgentLikeZbctl",
+	})
+	s.Require().NoError(err)
+	ctx, cancel := context.WithTimeout(context.Background(), utils.DefaultTestTimeout)
+	defer cancel()
+
+	_, err = client.NewTopologyCommand().Send(ctx)
+	userAgent := incomingContext["user-agent"]
+
+	// then
+	s.Require().Len(userAgent, 1)
+	s.Require().Contains(userAgent[0], "anotherUserAgentLikeZbctl")
+}
+
 func (s *clientTestSuite) TestCaCertificateEnvVar() {
 	// given
 	lis, grpcServer := createSecureServer(false)