Add OTLP protocol telemetry options (#1648)

loganrosen · Copilot · web-flow · commit b5ce1c895eff · 2026-06-16T02:19:58.000Z
* Add OTLP protocol telemetry options

Expose OTLP HTTP protocol selection through each SDK telemetry config and map the values to the standard OpenTelemetry protocol environment variables when spawning the Copilot CLI.

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;

* Remove signal-specific OTLP protocol options

Keep the SDK telemetry API focused on the global OTLP HTTP protocol option and rely on direct environment variables for uncommon signal-specific overrides.

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;

* Address telemetry protocol review feedback

Narrow the Python OTLP protocol type, avoid hardcoding the CLI default in docs, and add Rust serde coverage tying protocol wire values to env values.

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;

* Fix Python telemetry protocol docstring lint

Wrap the OTLP protocol TypedDict docstring so Python CI lint passes.

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;

---------

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;
diff --git a/docs/getting-started.md b/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:
diff --git a/docs/observability/opentelemetry.md b/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.
diff --git a/dotnet/README.md b/dotnet/README.md
@@ -752,6 +752,7 @@ 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
diff --git a/dotnet/src/Client.cs b/dotnet/src/Client.cs
@@ -1875,6 +1875,7 @@ 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;
diff --git a/dotnet/src/Types.cs b/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>
diff --git a/dotnet/test/E2E/ClientOptionsE2ETests.cs b/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,
diff --git a/dotnet/test/Unit/TelemetryTests.cs b/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);
diff --git a/go/README.md b/go/README.md
@@ -599,6 +599,7 @@ 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
diff --git a/go/client.go b/go/client.go
@@ -1752,6 +1752,9 @@ 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)
 		}
diff --git a/go/internal/e2e/client_options_e2e_test.go b/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,
diff --git a/go/internal/e2e/telemetry_e2e_test.go b/go/internal/e2e/telemetry_e2e_test.go
@@ -293,6 +293,9 @@ 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)
 		}
@@ -311,6 +314,7 @@ 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",
@@ -319,6 +323,9 @@ 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)
 		}
diff --git a/go/types.go b/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
diff --git a/java/src/main/java/com/github/copilot/CliServerManager.java b/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());
             }
diff --git a/java/src/main/java/com/github/copilot/rpc/TelemetryConfig.java b/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>
diff --git a/java/src/test/java/com/github/copilot/CliServerManagerTest.java b/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);
 
diff --git a/java/src/test/java/com/github/copilot/TelemetryConfigTest.java b/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());
diff --git a/nodejs/README.md b/nodejs/README.md
@@ -808,6 +808,7 @@ 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
diff --git a/nodejs/src/client.ts b/nodejs/src/client.ts
@@ -2029,6 +2029,8 @@ 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)
diff --git a/nodejs/src/types.ts b/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. */
diff --git a/nodejs/test/e2e/client_options.e2e.test.ts b/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");
diff --git a/nodejs/test/telemetry.test.ts b/nodejs/test/telemetry.test.ts
diff --git a/python/README.md b/python/README.md
diff --git a/python/copilot/client.py b/python/copilot/client.py
diff --git a/python/e2e/test_client_options_e2e.py b/python/e2e/test_client_options_e2e.py
diff --git a/python/e2e/test_telemetry_e2e.py b/python/e2e/test_telemetry_e2e.py
diff --git a/python/test_telemetry.py b/python/test_telemetry.py
diff --git a/rust/README.md b/rust/README.md
diff --git a/rust/src/lib.rs b/rust/src/lib.rs

Original file line number	Diff line number	Diff line change
`@@ -1875,6 +1875,7 @@ private static bool IsUnsupportedConnectMethod(RemoteRpcException ex)`
`1875`	`1875`	`{`
`1876`	`1876`	`startInfo.Environment["COPILOT_OTEL_ENABLED"] = "true";`
`1877`	`1877`	`if (telemetry.OtlpEndpoint is not null) startInfo.Environment["OTEL_EXPORTER_OTLP_ENDPOINT"] = telemetry.OtlpEndpoint;`
	`1878`	`+ if (telemetry.OtlpProtocol is not null) startInfo.Environment["OTEL_EXPORTER_OTLP_PROTOCOL"] = telemetry.OtlpProtocol;`
`1878`	`1879`	`if (telemetry.FilePath is not null) startInfo.Environment["COPILOT_OTEL_FILE_EXPORTER_PATH"] = telemetry.FilePath;`
`1879`	`1880`	`if (telemetry.ExporterType is not null) startInfo.Environment["COPILOT_OTEL_EXPORTER_TYPE"] = telemetry.ExporterType;`
`1880`	`1881`	`if (telemetry.SourceName is not null) startInfo.Environment["COPILOT_OTEL_SOURCE_NAME"] = telemetry.SourceName;`
Original file line number	Diff line number	Diff line change
`@@ -1752,6 +1752,9 @@ func (c *Client) startCLIServer(ctx context.Context) error {`
`1752`	`1752`	`if t.OTLPEndpoint != "" {`
`1753`	`1753`	`c.process.Env = setEnvValue(c.process.Env, "OTEL_EXPORTER_OTLP_ENDPOINT", t.OTLPEndpoint)`
`1754`	`1754`	`}`
	`1755`	`+ if t.OTLPProtocol != "" {`
	`1756`	`+ c.process.Env = setEnvValue(c.process.Env, "OTEL_EXPORTER_OTLP_PROTOCOL", t.OTLPProtocol)`
	`1757`	`+ }`
`1755`	`1758`	`if t.FilePath != "" {`
`1756`	`1759`	`c.process.Env = setEnvValue(c.process.Env, "COPILOT_OTEL_FILE_EXPORTER_PATH", t.FilePath)`
`1757`	`1760`	`}`