Introduce client metadata headers

Author: Prince Rachit Sinha

dev/gpctl/cmd/clusters.go

@@ -88,7 +88,7 @@ func getClustersClient(ctx context.Context) (*grpc.ClientConn, api.ClusterServic
 		secopt = grpc.WithTransportCredentials(creds)
 	}
 
-	conn, err := grpc.Dial(fmt.Sprintf("localhost:%s", localPort), secopt)
+	conn, err := grpc.Dial(fmt.Sprintf("localhost:%s", localPort), secopt, util.WithClientUnaryInterceptor())
 	if err != nil {
 		return nil, nil, err
 	}

dev/gpctl/cmd/imagebuilds.go

@@ -78,7 +78,7 @@ func getImagebuildsClient(ctx context.Context) (*grpc.ClientConn, api.ImageBuild
 		secopt = grpc.WithTransportCredentials(creds)
 	}
 
-	conn, err := grpc.Dial(fmt.Sprintf("localhost:%d", freePort), secopt)
+	conn, err := grpc.Dial(fmt.Sprintf("localhost:%d", freePort), secopt, util.WithClientUnaryInterceptor())
 	if err != nil {
 		return nil, nil, err
 	}

dev/gpctl/cmd/workspaces.go

@@ -133,7 +133,7 @@ func getWorkspacesClient(ctx context.Context) (*grpc.ClientConn, api.WorkspaceMa
 
 		secopt = grpc.WithTransportCredentials(creds)
 	}
-	conn, err := grpc.Dial(addr, secopt)
+	conn, err := grpc.Dial(addr, secopt, util.WithClientUnaryInterceptor())
 	if err != nil {
 		return nil, nil, err
 	}

dev/gpctl/pkg/util/grpc.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2020 Gitpod GmbH. All rights reserved.
+// Licensed under the GNU Affero General Public License (AGPL).
+// See License-AGPL.txt in the project root for license information.
+
+package util
+
+import (
+	"context"
+	"os"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+const clientNameKey = "client-name"
+
+// create unique client names. Concatenate both HOST and HOSTNAME so that we can track the executions
+// from both linux and macos
+var clientName = "gpctl:" + os.Getenv("USER") + "@" + os.Getenv("HOSTNAME") + os.Getenv("HOST")
+
+func clientInterceptor(
+	ctx context.Context,
+	method string,
+	req interface{},
+	reply interface{},
+	cc *grpc.ClientConn,
+	invoker grpc.UnaryInvoker,
+	opts ...grpc.CallOption,
+) error {
+	ctx = metadata.AppendToOutgoingContext(ctx, clientNameKey, clientName)
+	err := invoker(ctx, method, req, reply, cc, opts...)
+	return err
+}
+
+func WithClientUnaryInterceptor() grpc.DialOption {
+	return grpc.WithUnaryInterceptor(clientInterceptor)
+}