feat(otlp): add custom headers support for OTLP exporter (#1)

Author: CalvinAllen

README.md

@@ -225,6 +225,7 @@ catch (Exception ex)
 | `ServiceVersion` | `string` | `"1.0.0"` | Service version |
 | `OtlpEndpoint` | `string` | `null` | OTLP collector endpoint (e.g., `http://localhost:4317`) |
 | `UseOtlpHttp` | `bool` | `false` | Use HTTP/protobuf instead of gRPC |
+| `OtlpHeaders` | `IDictionary<string, string>` | empty | Custom headers for OTLP requests (auth, API keys) |
 | `EnableConsoleExporter` | `bool` | `false` | Output telemetry to console (for debugging) |
 | `EnableTracing` | `bool` | `true` | Enable distributed tracing |
 | `EnableMetrics` | `bool` | `true` | Enable metrics collection |
@@ -256,6 +257,23 @@ VsixTelemetry.Initialize(new TelemetryConfiguration
 });
 ```
 
+### Example: Using Custom Headers (Honeycomb, etc.)
+
+```csharp
+var config = new TelemetryConfiguration
+{
+    ServiceName = "MyExtension",
+    OtlpEndpoint = "https://api.honeycomb.io:443",
+    UseOtlpHttp = true
+};
+
+// Add authentication headers
+config.OtlpHeaders["x-honeycomb-team"] = "your-api-key";
+config.OtlpHeaders["x-honeycomb-dataset"] = "your-dataset";
+
+VsixTelemetry.Initialize(config);
+```
+
 ---
 
 ## Dependency Injection

src/CodingWithCalvin.Otel4Vsix/TelemetryConfiguration.cs

@@ -40,6 +40,21 @@ public sealed class TelemetryConfiguration
         /// </remarks>
         public bool UseOtlpHttp { get; set; }
 
+        /// <summary>
+        /// Gets custom headers to include in OTLP export requests.
+        /// </summary>
+        /// <remarks>
+        /// Use this to add authentication headers (API keys, bearer tokens) or other custom headers
+        /// required by your telemetry backend.
+        /// <example>
+        /// <code>
+        /// config.OtlpHeaders["x-api-key"] = "your-api-key";
+        /// config.OtlpHeaders["Authorization"] = "Bearer your-token";
+        /// </code>
+        /// </example>
+        /// </remarks>
+        public IDictionary<string, string> OtlpHeaders { get; } = new Dictionary<string, string>();
+
         /// <summary>
         /// Gets or sets a value indicating whether the console exporter is enabled.
         /// </summary>

src/CodingWithCalvin.Otel4Vsix/VsixTelemetry.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.Metrics;
+using System.Linq;
 using System.Threading;
 using Microsoft.Extensions.Logging;
 using OpenTelemetry;
@@ -367,11 +368,7 @@ private static TracerProvider BuildTracerProvider(ResourceBuilder resourceBuilde
             {
                 builder.AddOtlpExporter(options =>
                 {
-                    options.Endpoint = new Uri(_configuration.OtlpEndpoint);
-                    options.Protocol = _configuration.UseOtlpHttp
-                        ? OtlpExportProtocol.HttpProtobuf
-                        : OtlpExportProtocol.Grpc;
-                    options.TimeoutMilliseconds = _configuration.ExportTimeoutMilliseconds;
+                    ConfigureOtlpExporter(options);
                 });
             }
 
@@ -395,11 +392,7 @@ private static OpenTelemetry.Metrics.MeterProvider BuildMeterProvider(ResourceBu
             {
                 builder.AddOtlpExporter(options =>
                 {
-                    options.Endpoint = new Uri(_configuration.OtlpEndpoint);
-                    options.Protocol = _configuration.UseOtlpHttp
-                        ? OtlpExportProtocol.HttpProtobuf
-                        : OtlpExportProtocol.Grpc;
-                    options.TimeoutMilliseconds = _configuration.ExportTimeoutMilliseconds;
+                    ConfigureOtlpExporter(options);
                 });
             }
 
@@ -427,11 +420,7 @@ private static ILoggerFactory BuildLoggerFactory(ResourceBuilder resourceBuilder
                     {
                         options.AddOtlpExporter(exporterOptions =>
                         {
-                            exporterOptions.Endpoint = new Uri(_configuration.OtlpEndpoint);
-                            exporterOptions.Protocol = _configuration.UseOtlpHttp
-                                ? OtlpExportProtocol.HttpProtobuf
-                                : OtlpExportProtocol.Grpc;
-                            exporterOptions.TimeoutMilliseconds = _configuration.ExportTimeoutMilliseconds;
+                            ConfigureOtlpExporter(exporterOptions);
                         });
                     }
 
@@ -444,6 +433,23 @@ private static ILoggerFactory BuildLoggerFactory(ResourceBuilder resourceBuilder
             });
         }
 
+        private static void ConfigureOtlpExporter(OtlpExporterOptions options)
+        {
+            options.Endpoint = new Uri(_configuration.OtlpEndpoint);
+            options.Protocol = _configuration.UseOtlpHttp
+                ? OtlpExportProtocol.HttpProtobuf
+                : OtlpExportProtocol.Grpc;
+            options.TimeoutMilliseconds = _configuration.ExportTimeoutMilliseconds;
+
+            // Add custom headers if configured
+            if (_configuration.OtlpHeaders.Count > 0)
+            {
+                var headerString = string.Join(",",
+                    _configuration.OtlpHeaders.Select(kvp => $"{kvp.Key}={kvp.Value}"));
+                options.Headers = headerString;
+            }
+        }
+
         private static void ThrowIfNotInitialized()
         {
             if (!_isInitialized)