Add HTTP/Protobuf exporter for OTLP Logs (#3225)

examples/Console/Program.cs

@@ -169,6 +169,9 @@ internal class LogsOptions
     {
         [Option("useExporter", Default = "otlp", HelpText = "Options include otlp or console.", Required = false)]
         public string UseExporter { get; set; }
+
+        [Option('p', "protocol", HelpText = "Transport protocol used by OTLP exporter. Supported values: grpc and http/protobuf. Only applicable if Exporter is OTLP", Default = "grpc")]
+        public string Protocol { get; set; }
     }
 
     [Verb("inmemory", HelpText = "Specify the options required to test InMemory Exporter")]

examples/Console/TestLogs.cs

@@ -40,10 +40,10 @@ internal static object Run(LogsOptions options)
                          * launch the OpenTelemetry Collector with an OTLP receiver, by running:
                          *
                          *  - On Unix based systems use:
-                         *     docker run --rm -it -p 4317:4317 -v $(pwd):/cfg otel/opentelemetry-collector:0.33.0 --config=/cfg/otlp-collector-example/config.yaml
+                         *     docker run --rm -it -p 4317:4317 -p 4318:4318 -v $(pwd):/cfg otel/opentelemetry-collector:0.48.0 --config=/cfg/otlp-collector-example/config.yaml
                          *
                          *  - On Windows use:
-                         *     docker run --rm -it -p 4317:4317 -v "%cd%":/cfg otel/opentelemetry-collector:0.33.0 --config=/cfg/otlp-collector-example/config.yaml
+                         *     docker run --rm -it -p 4317:4317 -p 4318:4318 -v "%cd%":/cfg otel/opentelemetry-collector:0.48.0 --config=/cfg/otlp-collector-example/config.yaml
                          *
                          * Open another terminal window at the examples/Console/ directory and
                          * launch the OTLP example by running:
@@ -59,7 +59,28 @@ internal static object Run(LogsOptions options)
                         // See: https://docs.microsoft.com/aspnet/core/grpc/troubleshoot#call-insecure-grpc-services-with-net-core-client
                         AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);
 
-                        opt.AddOtlpExporter();
+                        if (options.Protocol.Trim().ToLower().Equals("grpc"))
+                        {
+                            opt.AddOtlpExporter(otlpOptions =>
+                            {
+                                otlpOptions.Protocol = OpenTelemetry.Exporter.OtlpExportProtocol.Grpc;
+                            });
+                        }
+                        else if (options.Protocol.Trim().ToLower().Equals("http/protobuf"))
+                        {
+                            opt.AddOtlpExporter(otlpOptions =>
+                            {
+                                otlpOptions.Protocol = OpenTelemetry.Exporter.OtlpExportProtocol.HttpProtobuf;
+                            });
+                        }
+                        else
+                        {
+                            System.Console.WriteLine($"Export protocol {options.Protocol} is not supported. Default protocol 'grpc' will be used.");
+                            opt.AddOtlpExporter(otlpOptions =>
+                            {
+                                otlpOptions.Protocol = OpenTelemetry.Exporter.OtlpExportProtocol.Grpc;
+                            });
+                        }
                     }
                     else
                     {

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/CHANGELOG.md

@@ -5,6 +5,10 @@
 * LogExporter to support Logging Scopes.
   ([#3277](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3217))
 
+* Support `HttpProtobuf` protocol with logs & added `HttpClientFactory`
+option
+([#3224](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3224))
+
 ## 1.3.0-beta.1
 
 Released 2022-Apr-15

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpGrpcLogExportClient.cs

@@ -21,7 +21,7 @@
 
 namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.ExportClient
 {
-    /// <summary>Class for sending OTLP metrics export request over gRPC.</summary>
+    /// <summary>Class for sending OTLP Logs export request over gRPC.</summary>
     internal sealed class OtlpGrpcLogExportClient : BaseOtlpGrpcExportClient<OtlpCollector.ExportLogsServiceRequest>
     {
         private readonly OtlpCollector.LogsService.LogsServiceClient logsClient;

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpHttpLogExportClient.cs

@@ -0,0 +1,86 @@
+// <copyright file="OtlpHttpLogExportClient.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.IO;
+using System.Net;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Runtime.CompilerServices;
+#if NET5_0_OR_GREATER
+using System.Threading;
+#endif
+using System.Threading.Tasks;
+using Google.Protobuf;
+using OtlpCollector = Opentelemetry.Proto.Collector.Logs.V1;
+
+namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.ExportClient
+{
+    /// <summary>Class for sending OTLP log export request over HTTP.</summary>
+    internal sealed class OtlpHttpLogExportClient : BaseOtlpHttpExportClient<OtlpCollector.ExportLogsServiceRequest>
+    {
+        internal const string MediaContentType = "application/x-protobuf";
+        private const string LogsExportPath = "v1/logs";
+
+        public OtlpHttpLogExportClient(OtlpExporterOptions options, HttpClient httpClient)
+            : base(options, httpClient, LogsExportPath)
+        {
+        }
+
+        protected override HttpContent CreateHttpContent(OtlpCollector.ExportLogsServiceRequest exportRequest)
+        {
+            return new ExportRequestContent(exportRequest);
+        }
+
+        internal sealed class ExportRequestContent : HttpContent
+        {
+            private static readonly MediaTypeHeaderValue ProtobufMediaTypeHeader = new(MediaContentType);
+
+            private readonly OtlpCollector.ExportLogsServiceRequest exportRequest;
+
+            public ExportRequestContent(OtlpCollector.ExportLogsServiceRequest exportRequest)
+            {
+                this.exportRequest = exportRequest;
+                this.Headers.ContentType = ProtobufMediaTypeHeader;
+            }
+
+#if NET5_0_OR_GREATER
+            protected override void SerializeToStream(Stream stream, TransportContext context, CancellationToken cancellationToken)
+            {
+                this.SerializeToStreamInternal(stream);
+            }
+#endif
+
+            protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
+            {
+                this.SerializeToStreamInternal(stream);
+                return Task.CompletedTask;
+            }
+
+            protected override bool TryComputeLength(out long length)
+            {
+                // We can't know the length of the content being pushed to the output stream.
+                length = -1;
+                return false;
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            private void SerializeToStreamInternal(Stream stream)
+            {
+                this.exportRequest.WriteTo(stream);
+            }
+        }
+    }
+}

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptionsExtensions.cs

@@ -22,6 +22,7 @@
 #if NETSTANDARD2_1 || NET5_0_OR_GREATER
 using Grpc.Net.Client;
 #endif
+using LogOtlpCollector = Opentelemetry.Proto.Collector.Logs.V1;
 using MetricsOtlpCollector = Opentelemetry.Proto.Collector.Metrics.V1;
 using TraceOtlpCollector = Opentelemetry.Proto.Collector.Trace.V1;
 
@@ -110,6 +111,16 @@ public static THeaders GetHeaders<THeaders>(this OtlpExporterOptions options, Ac
                 _ => throw new NotSupportedException($"Protocol {options.Protocol} is not supported."),
             };
 
+        public static IExportClient<LogOtlpCollector.ExportLogsServiceRequest> GetLogExportClient(this OtlpExporterOptions options) =>
+            options.Protocol switch
+            {
+                OtlpExportProtocol.Grpc => new OtlpGrpcLogExportClient(options),
+                OtlpExportProtocol.HttpProtobuf => new OtlpHttpLogExportClient(
+                    options,
+                    options.HttpClientFactory?.Invoke() ?? throw new InvalidOperationException("OtlpExporterOptions was missing HttpClientFactory or it returned null.")),
+                _ => throw new NotSupportedException($"Protocol {options.Protocol} is not supported."),
+            };
+
         public static OtlpExportProtocol? ToOtlpExportProtocol(this string protocol) =>
             protocol.Trim() switch
             {

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpLogExporter.cs

@@ -55,8 +55,7 @@ internal OtlpLogExporter(OtlpExporterOptions options, IExportClient<OtlpCollecto
             }
             else
             {
-                // TODO: this instantiation should be aligned with the protocol option (grpc or http/protobuf) when OtlpHttpMetricsExportClient will be implemented.
-                this.exportClient = new OtlpGrpcLogExportClient(options);
+                this.exportClient = options.GetLogExportClient();
             }
         }