Add OTLP protocol telemetry options

docs/getting-started.md

@@ -2227,11 +2227,14 @@ Dependency: `io.opentelemetry:opentelemetry-api`
 | Option | Node.js | Python | Go | Rust | Java | .NET | Description |
 |---|---|---|---|---|---|---|---|
 | OTLP endpoint | `otlpEndpoint` | `otlp_endpoint` | `OTLPEndpoint` | `otlp_endpoint` | `otlpEndpoint` | `OtlpEndpoint` | OTLP HTTP endpoint URL |
+| OTLP protocol | `otlpProtocol` | `otlp_protocol` | `OTLPProtocol` | `otlp_protocol` | `otlpProtocol` | `OtlpProtocol` | OTLP HTTP protocol for all signals: `"http/json"` or `"http/protobuf"` |
 | File path | `filePath` | `file_path` | `FilePath` | `file_path` | `filePath` | `FilePath` | File path for JSON-lines trace output |
 | Exporter type | `exporterType` | `exporter_type` | `ExporterType` | `exporter_type` | `exporterType` | `ExporterType` | `"otlp-http"` or `"file"` |
 | Source name | `sourceName` | `source_name` | `SourceName` | `source_name` | `sourceName` | `SourceName` | Instrumentation scope name |
 | Capture content | `captureContent` | `capture_content` | `CaptureContent` | `capture_content` | `captureContent` | `CaptureContent` | Whether to capture message content |
 
+The OTLP protocol field configures the CLI's `"otlp-http"` exporter for all signals. Leave it unset to use the CLI default, or set it to `"http/protobuf"` to export protobuf over HTTP.
+
 ### File export
 
 To write traces to a local file instead of an OTLP endpoint:

docs/observability/opentelemetry.md

@@ -104,11 +104,14 @@ let client = Client::start(ClientOptions::new()
 | Option | Node.js | Python | Go | .NET | Java | Rust | Description |
 |---|---|---|---|---|---|---|---|
 | OTLP endpoint | `otlpEndpoint` | `otlp_endpoint` | `OTLPEndpoint` | `OtlpEndpoint` | `otlpEndpoint` | `otlp_endpoint` | OTLP HTTP endpoint URL |
+| OTLP protocol | `otlpProtocol` | `otlp_protocol` | `OTLPProtocol` | `OtlpProtocol` | `otlpProtocol` | `otlp_protocol` | OTLP HTTP protocol for all signals: `"http/json"` or `"http/protobuf"` |
 | File path | `filePath` | `file_path` | `FilePath` | `FilePath` | `filePath` | `file_path` | File path for JSON-lines trace output |
 | Exporter type | `exporterType` | `exporter_type` | `ExporterType` | `ExporterType` | `exporterType` | `exporter_type` | `"otlp-http"` or `"file"` |
 | Source name | `sourceName` | `source_name` | `SourceName` | `SourceName` | `sourceName` | `source_name` | Instrumentation scope name |
 | Capture content | `captureContent` | `capture_content` | `CaptureContent` | `CaptureContent` | `captureContent` | `capture_content` | Whether to capture message content |
 
+The OTLP protocol field configures the CLI's `"otlp-http"` exporter for all signals. Leave it unset to use the CLI default, or set it to `"http/protobuf"` to export protobuf over HTTP.
+
 ### Trace context propagation
 
 > **Most users don't need this.** The `TelemetryConfig` above is all you need to collect traces from the CLI. The trace context propagation described in this section is an **advanced feature** for applications that create their own OpenTelemetry spans and want them to appear in the **same distributed trace** as the CLI's spans.

dotnet/README.md

@@ -738,6 +738,7 @@ var client = new CopilotClient(new CopilotClientOptions
 **TelemetryConfig properties:**
 
 - `OtlpEndpoint` - OTLP HTTP endpoint URL
+- `OtlpProtocol` - OTLP HTTP protocol for all signals (`"http/json"` or `"http/protobuf"`)
 - `FilePath` - File path for JSON-lines trace output
 - `ExporterType` - `"otlp-http"` or `"file"`
 - `SourceName` - Instrumentation scope name

dotnet/src/Client.cs

@@ -1805,6 +1805,7 @@ private static bool IsUnsupportedConnectMethod(RemoteRpcException ex)
         {
             startInfo.Environment["COPILOT_OTEL_ENABLED"] = "true";
             if (telemetry.OtlpEndpoint is not null) startInfo.Environment["OTEL_EXPORTER_OTLP_ENDPOINT"] = telemetry.OtlpEndpoint;
+            if (telemetry.OtlpProtocol is not null) startInfo.Environment["OTEL_EXPORTER_OTLP_PROTOCOL"] = telemetry.OtlpProtocol;
             if (telemetry.FilePath is not null) startInfo.Environment["COPILOT_OTEL_FILE_EXPORTER_PATH"] = telemetry.FilePath;
             if (telemetry.ExporterType is not null) startInfo.Environment["COPILOT_OTEL_EXPORTER_TYPE"] = telemetry.ExporterType;
             if (telemetry.SourceName is not null) startInfo.Environment["COPILOT_OTEL_SOURCE_NAME"] = telemetry.SourceName;

dotnet/src/Types.cs

@@ -413,6 +413,14 @@ public sealed class TelemetryConfig
     /// </remarks>
     public string? OtlpEndpoint { get; set; }
 
+    /// <summary>
+    /// OTLP HTTP protocol for all signals (<c>"http/json"</c> or <c>"http/protobuf"</c>).
+    /// </summary>
+    /// <remarks>
+    /// Maps to the <c>OTEL_EXPORTER_OTLP_PROTOCOL</c> environment variable.
+    /// </remarks>
+    public string? OtlpProtocol { get; set; }
+
     /// <summary>
     /// File path for the file exporter.
     /// </summary>

dotnet/test/E2E/ClientOptionsE2ETests.cs

@@ -78,6 +78,7 @@ public async Task Should_Propagate_Process_Options_To_Spawned_Cli()
             Telemetry = new TelemetryConfig
             {
                 OtlpEndpoint = "http://127.0.0.1:4318",
+                OtlpProtocol = "http/protobuf",
                 FilePath = telemetryPath,
                 ExporterType = "file",
                 SourceName = "dotnet-sdk-e2e",
@@ -104,6 +105,7 @@ public async Task Should_Propagate_Process_Options_To_Spawned_Cli()
         Assert.Equal("process-option-token", capturedEnv.GetProperty("COPILOT_SDK_AUTH_TOKEN").GetString());
         Assert.Equal("true", capturedEnv.GetProperty("COPILOT_OTEL_ENABLED").GetString());
         Assert.Equal("http://127.0.0.1:4318", capturedEnv.GetProperty("OTEL_EXPORTER_OTLP_ENDPOINT").GetString());
+        Assert.Equal("http/protobuf", capturedEnv.GetProperty("OTEL_EXPORTER_OTLP_PROTOCOL").GetString());
         Assert.Equal(telemetryPath, capturedEnv.GetProperty("COPILOT_OTEL_FILE_EXPORTER_PATH").GetString());
         Assert.Equal("file", capturedEnv.GetProperty("COPILOT_OTEL_EXPORTER_TYPE").GetString());
         Assert.Equal("dotnet-sdk-e2e", capturedEnv.GetProperty("COPILOT_OTEL_SOURCE_NAME").GetString());
@@ -642,6 +644,7 @@ function saveCapture() {
               COPILOT_SDK_AUTH_TOKEN: process.env.COPILOT_SDK_AUTH_TOKEN,
               COPILOT_OTEL_ENABLED: process.env.COPILOT_OTEL_ENABLED,
               OTEL_EXPORTER_OTLP_ENDPOINT: process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
+              OTEL_EXPORTER_OTLP_PROTOCOL: process.env.OTEL_EXPORTER_OTLP_PROTOCOL,
               COPILOT_OTEL_FILE_EXPORTER_PATH: process.env.COPILOT_OTEL_FILE_EXPORTER_PATH,
               COPILOT_OTEL_EXPORTER_TYPE: process.env.COPILOT_OTEL_EXPORTER_TYPE,
               COPILOT_OTEL_SOURCE_NAME: process.env.COPILOT_OTEL_SOURCE_NAME,

dotnet/test/Unit/TelemetryTests.cs

@@ -16,6 +16,7 @@ public void TelemetryConfig_DefaultValues_AreNull()
         var config = new TelemetryConfig();
 
         Assert.Null(config.OtlpEndpoint);
+        Assert.Null(config.OtlpProtocol);
         Assert.Null(config.FilePath);
         Assert.Null(config.ExporterType);
         Assert.Null(config.SourceName);
@@ -28,13 +29,15 @@ public void TelemetryConfig_CanSetAllProperties()
         var config = new TelemetryConfig
         {
             OtlpEndpoint = "http://localhost:4318",
+            OtlpProtocol = "http/protobuf",
             FilePath = "/tmp/traces.json",
             ExporterType = "otlp-http",
             SourceName = "my-app",
             CaptureContent = true
         };
 
         Assert.Equal("http://localhost:4318", config.OtlpEndpoint);
+        Assert.Equal("http/protobuf", config.OtlpProtocol);
         Assert.Equal("/tmp/traces.json", config.FilePath);
         Assert.Equal("otlp-http", config.ExporterType);
         Assert.Equal("my-app", config.SourceName);

go/README.md

@@ -573,6 +573,7 @@ client, err := copilot.NewClient(copilot.ClientOptions{
 **TelemetryConfig fields:**
 
 - `OTLPEndpoint` (string): OTLP HTTP endpoint URL
+- `OTLPProtocol` (string): OTLP HTTP protocol for all signals (`"http/json"` or `"http/protobuf"`)
 - `FilePath` (string): File path for JSON-lines trace output
 - `ExporterType` (string): `"otlp-http"` or `"file"`
 - `SourceName` (string): Instrumentation scope name

go/client.go

@@ -1695,6 +1695,9 @@ func (c *Client) startCLIServer(ctx context.Context) error {
 		if t.OTLPEndpoint != "" {
 			c.process.Env = setEnvValue(c.process.Env, "OTEL_EXPORTER_OTLP_ENDPOINT", t.OTLPEndpoint)
 		}
+		if t.OTLPProtocol != "" {
+			c.process.Env = setEnvValue(c.process.Env, "OTEL_EXPORTER_OTLP_PROTOCOL", t.OTLPProtocol)
+		}
 		if t.FilePath != "" {
 			c.process.Env = setEnvValue(c.process.Env, "COPILOT_OTEL_FILE_EXPORTER_PATH", t.FilePath)
 		}

go/internal/e2e/client_options_e2e_test.go

@@ -110,6 +110,7 @@ func TestClientOptionsE2E(t *testing.T) {
 			opts.SessionIdleTimeoutSeconds = 17
 			opts.Telemetry = &copilot.TelemetryConfig{
 				OTLPEndpoint:   "http://127.0.0.1:4318",
+				OTLPProtocol:   "http/protobuf",
 				FilePath:       telemetryPath,
 				ExporterType:   "file",
 				SourceName:     "go-sdk-e2e",
@@ -147,6 +148,7 @@ func TestClientOptionsE2E(t *testing.T) {
 			"COPILOT_SDK_AUTH_TOKEN":                             "process-option-token",
 			"COPILOT_OTEL_ENABLED":                               "true",
 			"OTEL_EXPORTER_OTLP_ENDPOINT":                        "http://127.0.0.1:4318",
+			"OTEL_EXPORTER_OTLP_PROTOCOL":                        "http/protobuf",
 			"COPILOT_OTEL_FILE_EXPORTER_PATH":                    telemetryPath,
 			"COPILOT_OTEL_EXPORTER_TYPE":                         "file",
 			"COPILOT_OTEL_SOURCE_NAME":                           "go-sdk-e2e",
@@ -195,6 +197,7 @@ func TestClientOptionsE2E(t *testing.T) {
 			t.Errorf("Expected session.create.params.includeSubAgentStreamingEvents=false, got %v", params["includeSubAgentStreamingEvents"])
 		}
 	})
+
 }
 
 // ---------------------------------------------------------------------------
@@ -372,6 +375,7 @@ function saveCapture() {
       COPILOT_SDK_AUTH_TOKEN: process.env.COPILOT_SDK_AUTH_TOKEN,
       COPILOT_OTEL_ENABLED: process.env.COPILOT_OTEL_ENABLED,
       OTEL_EXPORTER_OTLP_ENDPOINT: process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
+      OTEL_EXPORTER_OTLP_PROTOCOL: process.env.OTEL_EXPORTER_OTLP_PROTOCOL,
       COPILOT_OTEL_FILE_EXPORTER_PATH: process.env.COPILOT_OTEL_FILE_EXPORTER_PATH,
       COPILOT_OTEL_EXPORTER_TYPE: process.env.COPILOT_OTEL_EXPORTER_TYPE,
       COPILOT_OTEL_SOURCE_NAME: process.env.COPILOT_OTEL_SOURCE_NAME,

go/internal/e2e/telemetry_e2e_test.go

@@ -307,6 +307,9 @@ func TestTelemetryConfigUnit(t *testing.T) {
 		if cfg.OTLPEndpoint != "" {
 			t.Errorf("Expected empty OTLPEndpoint, got %q", cfg.OTLPEndpoint)
 		}
+		if cfg.OTLPProtocol != "" {
+			t.Errorf("Expected empty OTLPProtocol, got %q", cfg.OTLPProtocol)
+		}
 		if cfg.FilePath != "" {
 			t.Errorf("Expected empty FilePath, got %q", cfg.FilePath)
 		}
@@ -325,6 +328,7 @@ func TestTelemetryConfigUnit(t *testing.T) {
 		// Mirrors: TelemetryConfig_CanSetAllProperties
 		cfg := copilot.TelemetryConfig{
 			OTLPEndpoint:   "http://localhost:4318",
+			OTLPProtocol:   "http/protobuf",
 			FilePath:       "/tmp/traces.json",
 			ExporterType:   "otlp-http",
 			SourceName:     "my-app",
@@ -333,6 +337,9 @@ func TestTelemetryConfigUnit(t *testing.T) {
 		if cfg.OTLPEndpoint != "http://localhost:4318" {
 			t.Errorf("OTLPEndpoint mismatch: %q", cfg.OTLPEndpoint)
 		}
+		if cfg.OTLPProtocol != "http/protobuf" {
+			t.Errorf("OTLPProtocol mismatch: %q", cfg.OTLPProtocol)
+		}
 		if cfg.FilePath != "/tmp/traces.json" {
 			t.Errorf("FilePath mismatch: %q", cfg.FilePath)
 		}

go/types.go

@@ -159,6 +159,10 @@ type TelemetryConfig struct {
 	// Sets OTEL_EXPORTER_OTLP_ENDPOINT.
 	OTLPEndpoint string
 
+	// OTLPProtocol is the OTLP HTTP protocol for all signals.
+	// Sets OTEL_EXPORTER_OTLP_PROTOCOL.
+	OTLPProtocol string
+
 	// FilePath is the file path for JSON-lines trace output.
 	// Sets COPILOT_OTEL_FILE_EXPORTER_PATH.
 	FilePath string

java/src/main/java/com/github/copilot/CliServerManager.java

@@ -150,6 +150,9 @@ ProcessInfo startCliServer() throws IOException, InterruptedException {
             if (telemetry.getOtlpEndpoint() != null) {
                 pb.environment().put("OTEL_EXPORTER_OTLP_ENDPOINT", telemetry.getOtlpEndpoint());
             }
+            if (telemetry.getOtlpProtocol() != null) {
+                pb.environment().put("OTEL_EXPORTER_OTLP_PROTOCOL", telemetry.getOtlpProtocol());
+            }
             if (telemetry.getFilePath() != null) {
                 pb.environment().put("COPILOT_OTEL_FILE_EXPORTER_PATH", telemetry.getFilePath());
             }

java/src/main/java/com/github/copilot/rpc/TelemetryConfig.java

@@ -30,6 +30,7 @@
 public class TelemetryConfig {
 
     private String otlpEndpoint;
+    private String otlpProtocol;
     private String filePath;
     private String exporterType;
     private String sourceName;
@@ -58,6 +59,29 @@ public TelemetryConfig setOtlpEndpoint(String otlpEndpoint) {
         return this;
     }
 
+    /**
+     * Gets the OTLP HTTP protocol for all signals.
+     * <p>
+     * Maps to the {@code OTEL_EXPORTER_OTLP_PROTOCOL} environment variable.
+     *
+     * @return the OTLP HTTP protocol, or {@code null}
+     */
+    public String getOtlpProtocol() {
+        return otlpProtocol;
+    }
+
+    /**
+     * Sets the OTLP HTTP protocol for all signals.
+     *
+     * @param otlpProtocol
+     *            the protocol ({@code "http/json"} or {@code "http/protobuf"})
+     * @return this config for method chaining
+     */
+    public TelemetryConfig setOtlpProtocol(String otlpProtocol) {
+        this.otlpProtocol = otlpProtocol;
+        return this;
+    }
+
     /**
      * Gets the file path for the file exporter.
      * <p>

java/src/test/java/com/github/copilot/CliServerManagerTest.java

@@ -231,8 +231,9 @@ void startCliServerWithNullCliPath() throws Exception {
     void startCliServerWithTelemetryAllOptions() throws Exception {
         // The telemetry env vars are applied before ProcessBuilder.start()
         // so even with a nonexistent CLI path, the telemetry code path is exercised
-        var telemetry = new TelemetryConfig().setOtlpEndpoint("http://localhost:4318").setFilePath("/tmp/telemetry.log")
-                .setExporterType("otlp-http").setSourceName("test-app").setCaptureContent(true);
+        var telemetry = new TelemetryConfig().setOtlpEndpoint("http://localhost:4318").setOtlpProtocol("http/protobuf")
+                .setFilePath("/tmp/telemetry.log").setExporterType("otlp-http").setSourceName("test-app")
+                .setCaptureContent(true);
         var options = new CopilotClientOptions().setCliPath(NONEXISTENT_CLI).setTelemetry(telemetry).setUseStdio(true);
         var manager = new CliServerManager(options);
 

java/src/test/java/com/github/copilot/TelemetryConfigTest.java

@@ -19,6 +19,7 @@ class TelemetryConfigTest {
     void defaultValuesAreNull() {
         var config = new TelemetryConfig();
         assertNull(config.getOtlpEndpoint());
+        assertNull(config.getOtlpProtocol());
         assertNull(config.getFilePath());
         assertNull(config.getExporterType());
         assertNull(config.getSourceName());
@@ -32,6 +33,13 @@ void otlpEndpointGetterSetter() {
         assertEquals("http://localhost:4318", config.getOtlpEndpoint());
     }
 
+    @Test
+    void otlpProtocolGetterSetter() {
+        var config = new TelemetryConfig();
+        config.setOtlpProtocol("http/protobuf");
+        assertEquals("http/protobuf", config.getOtlpProtocol());
+    }
+
     @Test
     void filePathGetterSetter() {
         var config = new TelemetryConfig();
@@ -65,10 +73,12 @@ void captureContentGetterSetter() {
 
     @Test
     void fluentChainingReturnsThis() {
-        var config = new TelemetryConfig().setOtlpEndpoint("http://localhost:4318").setFilePath("/tmp/spans.json")
-                .setExporterType("file").setSourceName("sdk-test").setCaptureContent(true);
+        var config = new TelemetryConfig().setOtlpEndpoint("http://localhost:4318").setOtlpProtocol("http/protobuf")
+                .setFilePath("/tmp/spans.json").setExporterType("file").setSourceName("sdk-test")
+                .setCaptureContent(true);
 
         assertEquals("http://localhost:4318", config.getOtlpEndpoint());
+        assertEquals("http/protobuf", config.getOtlpProtocol());
         assertEquals("/tmp/spans.json", config.getFilePath());
         assertEquals("file", config.getExporterType());
         assertEquals("sdk-test", config.getSourceName());

nodejs/README.md

@@ -786,6 +786,7 @@ With just this configuration, the CLI emits spans for every session, message, an
 **TelemetryConfig options:**
 
 - `otlpEndpoint?: string` - OTLP HTTP endpoint URL
+- `otlpProtocol?: "http/json" | "http/protobuf"` - OTLP HTTP protocol for all signals
 - `filePath?: string` - File path for JSON-lines trace output
 - `exporterType?: string` - `"otlp-http"` or `"file"`
 - `sourceName?: string` - Instrumentation scope name

nodejs/src/client.ts

@@ -1929,6 +1929,8 @@ export class CopilotClient {
                 envWithoutNodeDebug.COPILOT_OTEL_ENABLED = "true";
                 if (t.otlpEndpoint !== undefined)
                     envWithoutNodeDebug.OTEL_EXPORTER_OTLP_ENDPOINT = t.otlpEndpoint;
+                if (t.otlpProtocol !== undefined)
+                    envWithoutNodeDebug.OTEL_EXPORTER_OTLP_PROTOCOL = t.otlpProtocol;
                 if (t.filePath !== undefined)
                     envWithoutNodeDebug.COPILOT_OTEL_FILE_EXPORTER_PATH = t.filePath;
                 if (t.exporterType !== undefined)

nodejs/src/types.ts

@@ -55,6 +55,8 @@ export type TraceContextProvider = () => TraceContext | Promise<TraceContext>;
 export interface TelemetryConfig {
     /** OTLP HTTP endpoint URL for trace/metric export. Sets OTEL_EXPORTER_OTLP_ENDPOINT. */
     otlpEndpoint?: string;
+    /** OTLP HTTP protocol for all signals. Sets OTEL_EXPORTER_OTLP_PROTOCOL. */
+    otlpProtocol?: "http/json" | "http/protobuf";
     /** File path for JSON-lines trace output. Sets COPILOT_OTEL_FILE_EXPORTER_PATH. */
     filePath?: string;
     /** Exporter backend type: "otlp-http" or "file". Sets COPILOT_OTEL_EXPORTER_TYPE. */

nodejs/test/e2e/client_options.e2e.test.ts

@@ -29,6 +29,7 @@ function saveCapture() {
       COPILOT_SDK_AUTH_TOKEN: process.env.COPILOT_SDK_AUTH_TOKEN,
       COPILOT_OTEL_ENABLED: process.env.COPILOT_OTEL_ENABLED,
       OTEL_EXPORTER_OTLP_ENDPOINT: process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
+      OTEL_EXPORTER_OTLP_PROTOCOL: process.env.OTEL_EXPORTER_OTLP_PROTOCOL,
       COPILOT_OTEL_FILE_EXPORTER_PATH: process.env.COPILOT_OTEL_FILE_EXPORTER_PATH,
       COPILOT_OTEL_EXPORTER_TYPE: process.env.COPILOT_OTEL_EXPORTER_TYPE,
       COPILOT_OTEL_SOURCE_NAME: process.env.COPILOT_OTEL_SOURCE_NAME,
@@ -247,6 +248,7 @@ describe("Client options", async () => {
             sessionIdleTimeoutSeconds: 17,
             telemetry: {
                 otlpEndpoint: "http://127.0.0.1:4318",
+                otlpProtocol: "http/protobuf",
                 filePath: telemetryPath,
                 exporterType: "file",
                 sourceName: "ts-sdk-e2e",
@@ -283,6 +285,7 @@ describe("Client options", async () => {
         expect(capture.env.COPILOT_SDK_AUTH_TOKEN).toBe("process-option-token");
         expect(capture.env.COPILOT_OTEL_ENABLED).toBe("true");
         expect(capture.env.OTEL_EXPORTER_OTLP_ENDPOINT).toBe("http://127.0.0.1:4318");
+        expect(capture.env.OTEL_EXPORTER_OTLP_PROTOCOL).toBe("http/protobuf");
         expect(capture.env.COPILOT_OTEL_FILE_EXPORTER_PATH).toBe(telemetryPath);
         expect(capture.env.COPILOT_OTEL_EXPORTER_TYPE).toBe("file");
         expect(capture.env.COPILOT_OTEL_SOURCE_NAME).toBe("ts-sdk-e2e");