[otlp] Remove Grpc.Core support for .NET Framework and .NET Standard 2.0 in OTLP exporter

Directory.Packages.props

@@ -57,15 +57,6 @@
           even during major version bumps, so compatibility is not a concern here.
     -->
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="$(LatestRuntimeOutOfBandVer)" />
-
-    <!--
-        We use conservative versions of these packages where an upgrade might
-        introduce breaking changes.
-    -->
-    <PackageVersion Include="Google.Protobuf" Version="[3.22.5,4.0)" />
-    <PackageVersion Include="Grpc" Version="[2.44.0,3.0)" />
-    <PackageVersion Include="Grpc.Core" Version="[2.44.0,3.0)" />
-    <PackageVersion Include="Grpc.Net.Client" Version="[2.52.0,3.0)" />
   </ItemGroup>
 
   <ItemGroup>
@@ -97,6 +88,9 @@
     <PackageVersion Include="Grpc.AspNetCore" Version="[2.59.0,3.0)" />
     <PackageVersion Include="Grpc.AspNetCore.Server" Version="[2.59.0, 3.0)" />
     <PackageVersion Include="Grpc.Tools" Version="[2.59.0,3.0)" />
+    <PackageVersion Include="Google.Protobuf" Version="[3.22.5,4.0)" />
+    <PackageVersion Include="Grpc" Version="[2.44.0,3.0)" />
+    <PackageVersion Include="Grpc.Net.Client" Version="[2.52.0,3.0)" />
     <PackageVersion Include="Microsoft.CSharp" Version="[4.7.0]" />
     <PackageVersion Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" Version="[3.11.0-beta1.23525.2]" />
     <PackageVersion Include="Microsoft.Coyote" Version="1.7.11" />

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/CHANGELOG.md

@@ -7,6 +7,16 @@ Notes](../../RELEASENOTES.md).
 
 ## Unreleased
 
+* **Breaking Change**: .NET Framework and .NET Standard builds now default to
+  exporting over OTLP/HTTP instead of OTLP/gRPC. **This change could result in a
+  failure to export telemetry unless appropriate measures are taken.**
+  Additionally, if you explicitly configure the exporter to use OTLP/gRPC it may
+  result in a `NotSupportedException` without further configuration. Please
+  carefully review issue
+  ([#6209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6209))
+  for additional information and workarounds.
+  ([#6229](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6229))
+
 ## 1.11.2
 
 Released 2025-Mar-04

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

@@ -35,7 +35,9 @@ protected OtlpExportClient(OtlpExporterOptions options, HttpClient httpClient, s
         Guard.ThrowIfNull(signalPath);
 
         Uri exporterEndpoint;
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
         if (options.Protocol == OtlpExportProtocol.Grpc)
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
         {
             exporterEndpoint = options.Endpoint.AppendPathIfNotPresent(signalPath);
         }

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OpenTelemetry.Exporter.OpenTelemetryProtocol.csproj

@@ -23,10 +23,6 @@
     <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry\OpenTelemetry.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <PackageReference Include="Grpc.Core" Condition="'$(TargetFramework)' == 'netstandard2.0' OR '$(TargetFramework)' == '$(NetFrameworkMinimumSupportedVersion)'" />
-  </ItemGroup>
-
   <ItemGroup>
     <Reference Include="System.Net.Http" Condition="'$(TargetFramework)' == '$(NetFrameworkMinimumSupportedVersion)'" />
   </ItemGroup>

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExportProtocol.cs

@@ -11,6 +11,9 @@ public enum OtlpExportProtocol : byte
     /// <summary>
     /// OTLP over gRPC (corresponds to 'grpc' Protocol configuration option). Used as default.
     /// </summary>
+#if NET462_OR_GREATER || NETSTANDARD2_0
+    [Obsolete("CAUTION: OTLP/gRPC is no longer supported for .NET Framework or .NET Standard targets without supplying a properly configured HttpClientFactory. It is strongly encouraged that you migrate to using OTLP/HTTP.")]
+#endif
     Grpc = 0,
 
     /// <summary>

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExportProtocolParser.cs

@@ -10,7 +10,9 @@ public static bool TryParse(string value, out OtlpExportProtocol result)
         switch (value?.Trim())
         {
             case "grpc":
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
                 result = OtlpExportProtocol.Grpc;
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
                 return true;
             case "http/protobuf":
                 result = OtlpExportProtocol.HttpProtobuf;

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptions.cs

@@ -26,7 +26,11 @@ public class OtlpExporterOptions : IOtlpExporterOptions
 {
     internal const string DefaultGrpcEndpoint = "http://localhost:4317";
     internal const string DefaultHttpEndpoint = "http://localhost:4318";
+#if NET462_OR_GREATER || NETSTANDARD2_0
+    internal const OtlpExportProtocol DefaultOtlpExportProtocol = OtlpExportProtocol.HttpProtobuf;
+#else
     internal const OtlpExportProtocol DefaultOtlpExportProtocol = OtlpExportProtocol.Grpc;
+#endif
 
     internal static readonly KeyValuePair<string, string>[] StandardHeaders = new KeyValuePair<string, string>[]
     {
@@ -84,7 +88,9 @@ public Uri Endpoint
         {
             if (this.endpoint == null)
             {
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
                 return this.Protocol == OtlpExportProtocol.Grpc
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
                     ? new Uri(DefaultGrpcEndpoint)
                     : new Uri(DefaultHttpEndpoint);
             }

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptionsExtensions.cs

@@ -9,9 +9,6 @@
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation;
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.ExportClient;
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Transmission;
-#if NET462_OR_GREATER || NETSTANDARD2_0
-using Grpc.Core;
-#endif
 
 namespace OpenTelemetry.Exporter;
 
@@ -25,30 +22,6 @@ internal static class OtlpExporterOptionsExtensions
     private const string MetricsHttpServicePath = "v1/metrics";
     private const string LogsHttpServicePath = "v1/logs";
 
-#if NET462_OR_GREATER || NETSTANDARD2_0
-    public static Channel CreateChannel(this OtlpExporterOptions options)
-    {
-        if (options.Endpoint.Scheme != Uri.UriSchemeHttp && options.Endpoint.Scheme != Uri.UriSchemeHttps)
-        {
-            throw new NotSupportedException($"Endpoint URI scheme ({options.Endpoint.Scheme}) is not supported. Currently only \"http\" and \"https\" are supported.");
-        }
-
-        ChannelCredentials channelCredentials;
-        if (options.Endpoint.Scheme == Uri.UriSchemeHttps)
-        {
-            channelCredentials = new SslCredentials();
-        }
-        else
-        {
-            channelCredentials = ChannelCredentials.Insecure;
-        }
-
-        return new Channel(options.Endpoint.Authority, channelCredentials);
-    }
-
-    public static Metadata GetMetadataFromHeaders(this OtlpExporterOptions options) => options.GetHeaders<Metadata>((m, k, v) => m.Add(k, v));
-#endif
-
     public static THeaders GetHeaders<THeaders>(this OtlpExporterOptions options, Action<THeaders, string, string> addHeader)
         where THeaders : new()
     {
@@ -129,25 +102,12 @@ public static IExportClient GetExportClient(this OtlpExporterOptions options, Ot
     {
         var httpClient = options.HttpClientFactory?.Invoke() ?? throw new InvalidOperationException("OtlpExporterOptions was missing HttpClientFactory or it returned null.");
 
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
         if (options.Protocol != OtlpExportProtocol.Grpc && options.Protocol != OtlpExportProtocol.HttpProtobuf)
         {
             throw new NotSupportedException($"Protocol {options.Protocol} is not supported.");
         }
 
-#if NET462_OR_GREATER || NETSTANDARD2_0
-        if (options.Protocol == OtlpExportProtocol.Grpc)
-        {
-            var servicePath = otlpSignalType switch
-            {
-                OtlpSignalType.Traces => TraceGrpcServicePath,
-                OtlpSignalType.Metrics => MetricsGrpcServicePath,
-                OtlpSignalType.Logs => LogsGrpcServicePath,
-                _ => throw new NotSupportedException($"OtlpSignalType {otlpSignalType} is not supported."),
-            };
-            return new GrpcExportClient(options, servicePath);
-        }
-#endif
-
         return otlpSignalType switch
         {
             OtlpSignalType.Traces => options.Protocol == OtlpExportProtocol.Grpc
@@ -164,6 +124,7 @@ public static IExportClient GetExportClient(this OtlpExporterOptions options, Ot
 
             _ => throw new NotSupportedException($"OtlpSignalType {otlpSignalType} is not supported."),
         };
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
     }
 
     public static void TryEnableIHttpClientFactoryIntegration(this OtlpExporterOptions options, IServiceProvider serviceProvider, string httpClientName)

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpLogExporterHelperExtensions.cs

@@ -284,6 +284,17 @@ internal static BaseProcessor<LogRecord> BuildOtlpLogExporter(
         Debug.Assert(sdkLimitOptions != null, "sdkLimitOptions was null");
         Debug.Assert(experimentalOptions != null, "experimentalOptions was null");
 
+#if NET462_OR_GREATER || NETSTANDARD2_0
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
+        if (exporterOptions!.Protocol == OtlpExportProtocol.Grpc &&
+            ReferenceEquals(exporterOptions.HttpClientFactory, exporterOptions.DefaultHttpClientFactory))
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
+        {
+            throw new NotSupportedException("OtlpExportProtocol.Grpc with the default HTTP client factory is not supported on .NET Framework or .NET Standard 2.0." +
+                "Please switch to OtlpExportProtocol.HttpProtobuf or provide a custom HttpClientFactory.");
+        }
+#endif
+
         if (!skipUseOtlpExporterRegistrationCheck)
         {
             serviceProvider!.EnsureNoUseOtlpExporterRegistrations();

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpMetricExporterExtensions.cs

@@ -168,6 +168,17 @@ internal static MetricReader BuildOtlpExporterMetricReader(
         Debug.Assert(metricReaderOptions != null, "metricReaderOptions was null");
         Debug.Assert(experimentalOptions != null, "experimentalOptions was null");
 
+#if NET462_OR_GREATER || NETSTANDARD2_0
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
+        if (exporterOptions!.Protocol == OtlpExportProtocol.Grpc &&
+            ReferenceEquals(exporterOptions.HttpClientFactory, exporterOptions.DefaultHttpClientFactory))
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
+        {
+            throw new NotSupportedException("OtlpExportProtocol.Grpc with the default HTTP client factory is not supported on .NET Framework or .NET Standard 2.0." +
+                "Please switch to OtlpExportProtocol.HttpProtobuf or provide a custom HttpClientFactory.");
+        }
+#endif
+
         if (!skipUseOtlpExporterRegistrationCheck)
         {
             serviceProvider!.EnsureNoUseOtlpExporterRegistrations();

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpTraceExporterHelperExtensions.cs

@@ -129,6 +129,17 @@ internal static BaseProcessor<Activity> BuildOtlpExporterProcessor(
         Debug.Assert(experimentalOptions != null, "experimentalOptions was null");
         Debug.Assert(batchExportProcessorOptions != null, "batchExportProcessorOptions was null");
 
+#if NET462_OR_GREATER || NETSTANDARD2_0
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
+        if (exporterOptions!.Protocol == OtlpExportProtocol.Grpc &&
+            ReferenceEquals(exporterOptions.HttpClientFactory, exporterOptions.DefaultHttpClientFactory))
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
+        {
+            throw new NotSupportedException("OtlpExportProtocol.Grpc with the default HTTP client factory is not supported on .NET Framework or .NET Standard 2.0." +
+                "Please switch to OtlpExportProtocol.HttpProtobuf or provide a custom HttpClientFactory.");
+        }
+#endif
+
         if (!skipUseOtlpExporterRegistrationCheck)
         {
             serviceProvider!.EnsureNoUseOtlpExporterRegistrations();

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/IntegrationTest/IntegrationTests.cs

@@ -34,6 +34,7 @@ public void Dispose()
         this.openTelemetryEventListener.Dispose();
     }
 
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
     [InlineData(OtlpExportProtocol.Grpc, ":4317", ExportProcessorType.Batch, false)]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/traces", ExportProcessorType.Batch, false)]
     [InlineData(OtlpExportProtocol.Grpc, ":4317", ExportProcessorType.Batch, true)]
@@ -44,6 +45,7 @@ public void Dispose()
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/traces", ExportProcessorType.Simple, true)]
     [InlineData(OtlpExportProtocol.Grpc, ":5317", ExportProcessorType.Simple, true, "https")]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":5318/v1/traces", ExportProcessorType.Simple, true, "https")]
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
     [Trait("CategoryName", "CollectorIntegrationTests")]
     [SkipUnlessEnvVarFoundTheory(CollectorHostnameEnvVarName)]
     public void TraceExportResultIsSuccess(OtlpExportProtocol protocol, string endpoint, ExportProcessorType exportProcessorType, bool forceFlush, string scheme = "http")
@@ -118,6 +120,7 @@ public void TraceExportResultIsSuccess(OtlpExportProtocol protocol, string endpo
         }
     }
 
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
     [InlineData(OtlpExportProtocol.Grpc, ":4317", false, false)]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/metrics", false, false)]
     [InlineData(OtlpExportProtocol.Grpc, ":4317", false, true)]
@@ -128,6 +131,7 @@ public void TraceExportResultIsSuccess(OtlpExportProtocol protocol, string endpo
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/metrics", true, true)]
     [InlineData(OtlpExportProtocol.Grpc, ":5317", true, true, "https")]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":5318/v1/metrics", true, true, "https")]
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
     [Trait("CategoryName", "CollectorIntegrationTests")]
     [SkipUnlessEnvVarFoundTheory(CollectorHostnameEnvVarName)]
     public void MetricExportResultIsSuccess(OtlpExportProtocol protocol, string endpoint, bool useManualExport, bool forceFlush, string scheme = "http")
@@ -202,12 +206,14 @@ public void MetricExportResultIsSuccess(OtlpExportProtocol protocol, string endp
         }
     }
 
+#pragma warning disable CS0618 // Suppressing gRPC obsolete warning
     [InlineData(OtlpExportProtocol.Grpc, ":4317", ExportProcessorType.Batch)]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/logs", ExportProcessorType.Batch)]
     [InlineData(OtlpExportProtocol.Grpc, ":4317", ExportProcessorType.Simple)]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":4318/v1/logs", ExportProcessorType.Simple)]
     [InlineData(OtlpExportProtocol.Grpc, ":5317", ExportProcessorType.Simple, "https")]
     [InlineData(OtlpExportProtocol.HttpProtobuf, ":5318/v1/logs", ExportProcessorType.Simple, "https")]
+#pragma warning restore CS0618 // Suppressing gRPC obsolete warning
     [Trait("CategoryName", "CollectorIntegrationTests")]
     [SkipUnlessEnvVarFoundTheory(CollectorHostnameEnvVarName)]
     public void LogExportResultIsSuccess(OtlpExportProtocol protocol, string endpoint, ExportProcessorType exportProcessorType, string scheme = "http")