[mcp] SDK integration with Streamable HTTP transport (Phase 1.2)

cmd/jaeger/internal/extension/jaegermcp/README.md

@@ -16,7 +16,7 @@ This approach prevents context-window exhaustion in LLMs and enables more effici
 
 ## Status
 
-🚧 **Phase 1: Foundation (In Progress)** - Extension scaffold and lifecycle management
+✅ **Phase 1: Foundation (Complete)** - Extension scaffold, lifecycle management, and MCP SDK integration
 
 Future phases will add:
 - Phase 2: Basic MCP tools (search, span details, errors)
@@ -54,5 +54,6 @@ Phase 1 implements:
 - ✅ Configuration validation
 - ✅ Factory implementation
 - ✅ Server lifecycle management
-- ✅ Basic health endpoint
-- 🚧 MCP SDK integration (coming in Phase 2)
+- ✅ MCP SDK integration
+- ✅ Streamable HTTP transport
+- ✅ Basic health tool (placeholder for Phase 2)

cmd/jaeger/internal/extension/jaegermcp/config.go

@@ -18,7 +18,7 @@ type Config struct {
 	ServerName string `mapstructure:"server_name"`
 
 	// ServerVersion is the version of the MCP server.
-	ServerVersion string `mapstructure:"server_version"`
+	ServerVersion string `mapstructure:"server_version" valid:"required"`
 
 	// MaxSpanDetailsPerRequest limits the number of spans that can be fetched in a single request.
 	MaxSpanDetailsPerRequest int `mapstructure:"max_span_details_per_request" valid:"range(1|100)"`

cmd/jaeger/internal/extension/jaegermcp/config_test.go

@@ -16,13 +16,17 @@ func TestValidate(t *testing.T) {
 		expectError bool
 	}{
 		{
-			name:        "Empty config - valid",
-			config:      &Config{},
-			expectError: false,
+			name: "Empty config - invalid (missing ServerVersion)",
+			config: &Config{
+				MaxSpanDetailsPerRequest: 20,
+				MaxSearchResults:         100,
+			},
+			expectError: true,
 		},
 		{
 			name: "Valid config",
 			config: &Config{
+				ServerVersion:            "1.0.0",
 				MaxSpanDetailsPerRequest: 20,
 				MaxSearchResults:         100,
 			},
@@ -31,6 +35,7 @@ func TestValidate(t *testing.T) {
 		{
 			name: "Invalid MaxSpanDetailsPerRequest (too high)",
 			config: &Config{
+				ServerVersion:            "1.0.0",
 				MaxSpanDetailsPerRequest: 101,
 				MaxSearchResults:         100,
 			},
@@ -39,6 +44,7 @@ func TestValidate(t *testing.T) {
 		{
 			name: "Invalid MaxSearchResults (too high)",
 			config: &Config{
+				ServerVersion:            "1.0.0",
 				MaxSpanDetailsPerRequest: 20,
 				MaxSearchResults:         1001,
 			},

cmd/jaeger/internal/extension/jaegermcp/server.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/extension"
 	"go.opentelemetry.io/collector/extension/extensioncapabilities"
@@ -30,6 +31,7 @@ type server struct {
 	telset     component.TelemetrySettings
 	httpServer *http.Server
 	listener   net.Listener
+	mcpServer  *mcp.Server
 }
 
 // newServer creates a new MCP server instance.
@@ -50,25 +52,48 @@ func (*server) Dependencies() []component.ID {
 func (s *server) Start(_ context.Context, host component.Host) error {
 	s.telset.Logger.Info("Starting Jaeger MCP server", zap.String("endpoint", s.config.HTTP.Endpoint))
 
-	// TODO Phase 2: Get QueryService from jaegerquery extension
+	// TODO Phase 2 (part 2): Get QueryService from jaegerquery extension
 	// This will require jaegerquery to expose QueryService through an Extension interface,
 	// similar to how jaegerstorage exposes storage factories.
 	// For now, we just verify that jaegerquery extension is available.
 	_ = host
 
-	// TODO: Initialize MCP server with Streamable HTTP transport
-	// This will be implemented in Phase 2 once we add the MCP SDK dependency
-
-	// For Phase 1, we just set up a basic HTTP server to validate the extension lifecycle
-	//nolint:noctx // Phase 1 temporary implementation, will be replaced with MCP SDK in Phase 2
+	// Initialize MCP server with implementation details
+	impl := &mcp.Implementation{
+		Name:    s.config.ServerName,
+		Version: s.config.ServerVersion,
+	}
+	// Pass nil for ServerOptions to use default settings.
+	// Custom options (e.g., logging, handlers) can be added in Phase 2 if needed.
+	s.mcpServer = mcp.NewServer(impl, nil)
+
+	// Register a placeholder health tool for Phase 1 Part 2
+	// Actual MCP tools will be implemented in Phase 2
+	mcp.AddTool(s.mcpServer, &mcp.Tool{
+		Name:        "health",
+		Description: "Check if the Jaeger MCP server is running",
+	}, s.healthTool)
+
+	// Set up TCP listener
 	listener, err := net.Listen("tcp", s.config.HTTP.Endpoint)
 	if err != nil {
 		return fmt.Errorf("failed to listen on %s: %w", s.config.HTTP.Endpoint, err)
 	}
 	s.listener = listener
 
-	// Create a basic HTTP server
+	// Create MCP streamable HTTP handler
+	mcpHandler := mcp.NewStreamableHTTPHandler(
+		func(_ *http.Request) *mcp.Server { return s.mcpServer },
+		&mcp.StreamableHTTPOptions{
+			JSONResponse:   false, // Use SSE for streamed events
+			Stateless:      false, // Session state management
+			SessionTimeout: 5 * time.Minute,
+		},
+	)
+
+	// Create HTTP server with MCP handler and health endpoint
 	mux := http.NewServeMux()
+	mux.Handle("/mcp", mcpHandler)
 	mux.HandleFunc("/health", func(w http.ResponseWriter, _ *http.Request) {
 		w.WriteHeader(http.StatusOK)
 		w.Write([]byte("MCP server is running"))
@@ -86,7 +111,9 @@ func (s *server) Start(_ context.Context, host component.Host) error {
 		}
 	}()
 
-	s.telset.Logger.Info("Jaeger MCP server started successfully", zap.String("endpoint", s.config.HTTP.Endpoint))
+	s.telset.Logger.Info("Jaeger MCP server started successfully",
+		zap.String("endpoint", s.config.HTTP.Endpoint),
+		zap.String("mcp_endpoint", "http://"+s.config.HTTP.Endpoint+"/mcp"))
 	return nil
 }
 
@@ -103,3 +130,24 @@ func (s *server) Shutdown(ctx context.Context) error {
 
 	return errors.Join(errs...)
 }
+
+// HealthToolOutput is the strongly-typed output for the health tool.
+type HealthToolOutput struct {
+	Status  string `json:"status" jsonschema:"Server status (ok/error)"`
+	Server  string `json:"server" jsonschema:"Server name"`
+	Version string `json:"version" jsonschema:"Server version"`
+}
+
+// healthTool is a placeholder MCP tool that checks server health.
+// Actual MCP tools for trace querying will be implemented in Phase 2.
+func (s *server) healthTool(
+	_ context.Context,
+	_ *mcp.CallToolRequest,
+	_ struct{},
+) (*mcp.CallToolResult, HealthToolOutput, error) {
+	return nil, HealthToolOutput{
+		Status:  "ok",
+		Server:  s.config.ServerName,
+		Version: s.config.ServerVersion,
+	}, nil
+}

cmd/jaeger/internal/extension/jaegermcp/server_test.go

@@ -5,6 +5,7 @@ package jaegermcp
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -32,7 +33,11 @@ func TestServerLifecycle(t *testing.T) {
 		{
 			name: "successful start and shutdown",
 			config: &Config{
-				HTTP: createDefaultConfig().(*Config).HTTP,
+				HTTP:                     createDefaultConfig().(*Config).HTTP,
+				ServerName:               "jaeger",
+				ServerVersion:            "1.0.0",
+				MaxSpanDetailsPerRequest: 20,
+				MaxSearchResults:         100,
 			},
 			expectedError: "",
 		},
@@ -86,6 +91,10 @@ func TestServerHealthEndpoint(t *testing.T) {
 		HTTP: confighttp.ServerConfig{
 			Endpoint: "localhost:0", // OS will assign a free port
 		},
+		ServerName:               "jaeger",
+		ServerVersion:            "1.0.0",
+		MaxSpanDetailsPerRequest: 20,
+		MaxSearchResults:         100,
 	}
 
 	server := newServer(config, telset)
@@ -96,12 +105,19 @@ func TestServerHealthEndpoint(t *testing.T) {
 		assert.NoError(t, err)
 	}()
 
-	// Give the server a moment to start
-	time.Sleep(100 * time.Millisecond)
-
 	// Get the actual address the server is listening on
 	addr := server.listener.Addr().String()
 
+	// Wait for server to be ready using assert.Eventually
+	assert.Eventually(t, func() bool {
+		resp, err := http.Get(fmt.Sprintf("http://%s/health", addr))
+		if err != nil {
+			return false
+		}
+		defer resp.Body.Close()
+		return resp.StatusCode == http.StatusOK
+	}, 1*time.Second, 10*time.Millisecond, "Server should be ready")
+
 	// Test the health endpoint
 	resp, err := http.Get(fmt.Sprintf("http://%s/health", addr))
 	require.NoError(t, err)
@@ -113,6 +129,64 @@ func TestServerHealthEndpoint(t *testing.T) {
 	assert.Equal(t, "MCP server is running", string(body))
 }
 
+func TestServerMCPEndpoint(t *testing.T) {
+	host := componenttest.NewNopHost()
+	telset := componenttest.NewNopTelemetrySettings()
+
+	// Use a random available port
+	config := &Config{
+		HTTP: confighttp.ServerConfig{
+			Endpoint: "localhost:0", // OS will assign a free port
+		},
+		ServerName:               "jaeger",
+		ServerVersion:            "1.0.0",
+		MaxSpanDetailsPerRequest: 20,
+		MaxSearchResults:         100,
+	}
+
+	server := newServer(config, telset)
+	err := server.Start(context.Background(), host)
+	require.NoError(t, err)
+	defer func() {
+		err := server.Shutdown(context.Background())
+		assert.NoError(t, err)
+	}()
+
+	// Get the actual address the server is listening on
+	addr := server.listener.Addr().String()
+
+	// Wait for server to be ready
+	assert.Eventually(t, func() bool {
+		resp, err := http.Get(fmt.Sprintf("http://%s/health", addr))
+		if err != nil {
+			return false
+		}
+		defer resp.Body.Close()
+		return resp.StatusCode == http.StatusOK
+	}, 1*time.Second, 10*time.Millisecond, "Server should be ready")
+
+	// Test the MCP endpoint with a GET request
+	// According to MCP Streamable HTTP spec, GET should return session info or error
+	resp, err := http.Get(fmt.Sprintf("http://%s/mcp", addr))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+
+	// The MCP endpoint should not return 404 (it exists)
+	assert.NotEqual(t, http.StatusNotFound, resp.StatusCode)
+
+	// Read and validate the response body if it's JSON
+	body, err := io.ReadAll(resp.Body)
+	require.NoError(t, err)
+
+	// If the response is JSON, it should be valid JSON
+	// The MCP spec indicates GET without session ID may return an error or session info
+	if resp.Header.Get("Content-Type") == "application/json" {
+		var result map[string]any
+		err := json.Unmarshal(body, &result)
+		assert.NoError(t, err, "Response should be valid JSON")
+	}
+}
+
 func TestServerShutdownWithError(t *testing.T) {
 	host := componenttest.NewNopHost()
 	telset := componenttest.NewNopTelemetrySettings()

go.mod

@@ -19,6 +19,7 @@ require (
 	github.com/gorilla/mux v1.8.1
 	github.com/jaegertracing/jaeger-idl v0.6.0
 	github.com/kr/pretty v0.3.1
+	github.com/modelcontextprotocol/go-sdk v1.2.0
 	github.com/olivere/elastic/v7 v7.0.32
 	github.com/open-telemetry/opentelemetry-collector-contrib/connector/spanmetricsconnector v0.142.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/kafkaexporter v0.142.0
@@ -121,6 +122,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/signin v1.0.1 // indirect
 	github.com/dennwc/varint v1.0.0 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
+	github.com/google/jsonschema-go v0.3.0 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
 	github.com/googleapis/gax-go/v2 v2.15.0 // indirect
@@ -138,6 +140,7 @@ require (
 	github.com/tg123/go-htpasswd v1.2.4 // indirect
 	github.com/twmb/franz-go/pkg/kadm v1.17.1 // indirect
 	github.com/xdg-go/scram v1.2.0 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	github.com/zeebo/xxh3 v1.0.2 // indirect
 	go.opentelemetry.io/collector/config/configopaque v1.49.0 // indirect
 	go.opentelemetry.io/collector/semconv v0.128.1-0.20250610090210-188191247685 // indirect

go.sum

@@ -258,6 +258,8 @@ github.com/google/go-tpm v0.9.8/go.mod h1:h9jEsEECg7gtLis0upRBQU+GhYVH6jMjrFxI8u
 github.com/google/go-tpm-tools v0.4.4 h1:oiQfAIkc6xTy9Fl5NKTeTJkBTlXdHsxAofmQyxBKY98=
 github.com/google/go-tpm-tools v0.4.4/go.mod h1:T8jXkp2s+eltnCDIsXR84/MTcVU9Ja7bh3Mit0pa4AY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
+github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
 github.com/google/s2a-go v0.1.9 h1:LGD7gtMgezd8a/Xak7mEWL0PjoTQFvpRudN895yqKW0=
 github.com/google/s2a-go v0.1.9/go.mod h1:YA0Ei2ZQL3acow2O62kdp9UlnvMmU7kA6Eutn0dXayM=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -404,6 +406,8 @@ github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zx
 github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/moby/docker-image-spec v1.3.1 h1:jMKff3w6PgbfSa69GfNg+zN/XLhfXJGnEx3Nl2EsFP0=
 github.com/moby/docker-image-spec v1.3.1/go.mod h1:eKmb5VW8vQEh/BAr2yvVNvuiJuY6UIocYsFu/DxxRpo=
+github.com/modelcontextprotocol/go-sdk v1.2.0 h1:Y23co09300CEk8iZ/tMxIX1dVmKZkzoSBZOpJwUnc/s=
+github.com/modelcontextprotocol/go-sdk v1.2.0/go.mod h1:6fM3LCm3yV7pAs8isnKLn07oKtB0MP9LHd3DfAcKw10=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -645,6 +649,8 @@ github.com/xdg-go/stringprep v1.0.4 h1:XLI/Ng3O1Atzq0oBs3TWm+5ZVgkq2aqdlvP9JtoZ6
 github.com/xdg-go/stringprep v1.0.4/go.mod h1:mPGuuIYwz7CmR2bT9j4GbQqutWS1zV24gijq1dTyGkM=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
+github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
+github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 github.com/youmark/pkcs8 v0.0.0-20181117223130-1be2e3e5546d/go.mod h1:rHwXgn7JulP+udvsHwJoVG1YGAP6VLg4y9I5dyZdqmA=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=