Add telemetry for initialize (docker#132)

* Add telemetry for initialize.

* Add intitialize span test.

Author: cmrigney

cmd/docker-mcp/internal/interceptors/telemetry.go

@@ -26,6 +26,11 @@ func TelemetryMiddleware() mcp.Middleware {
 			var tracked bool
 
 			switch method {
+			case "initialize":
+				params := req.GetParams().(*mcp.InitializeParams)
+				ctx, span = telemetry.StartInitializeSpan(ctx)
+				telemetry.RecordInitialize(ctx, params)
+				tracked = true
 			case "tools/list":
 				ctx, span = telemetry.StartListSpan(ctx, "tools")
 				telemetry.RecordListTools(ctx)

cmd/docker-mcp/internal/telemetry/telemetry.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
@@ -41,6 +42,9 @@ var (
 	// GatewayStartCounter tracks gateway starts
 	GatewayStartCounter metric.Int64Counter
 
+	// InitializeCounter tracks initialize calls
+	InitializeCounter metric.Int64Counter
+
 	// ListToolsCounter tracks list tools calls
 	ListToolsCounter metric.Int64Counter
 
@@ -134,6 +138,16 @@ func Init() {
 		}
 	}
 
+	InitializeCounter, err = meter.Int64Counter("mcp.initialize",
+		metric.WithDescription("Number of initialize calls"),
+		metric.WithUnit("1"))
+	if err != nil {
+		// Log error but don't fail
+		if os.Getenv("DOCKER_MCP_TELEMETRY_DEBUG") != "" {
+			fmt.Fprintf(os.Stderr, "[MCP-TELEMETRY] Error creating initialize counter: %v\n", err)
+		}
+	}
+
 	ListToolsCounter, err = meter.Int64Counter("mcp.list.tools",
 		metric.WithDescription("Number of list tools calls"),
 		metric.WithUnit("1"))
@@ -401,6 +415,13 @@ func StartPromptSpan(ctx context.Context, promptName string, attrs ...attribute.
 		trace.WithSpanKind(trace.SpanKindClient))
 }
 
+// StartListSpan starts a new span for a list operation (tools, prompts, resources)
+func StartInitializeSpan(ctx context.Context, attrs ...attribute.KeyValue) (context.Context, trace.Span) {
+	return tracer.Start(ctx, "mcp.initialize",
+		trace.WithAttributes(attrs...),
+		trace.WithSpanKind(trace.SpanKindServer))
+}
+
 // StartListSpan starts a new span for a list operation (tools, prompts, resources)
 func StartListSpan(ctx context.Context, listType string, attrs ...attribute.KeyValue) (context.Context, trace.Span) {
 	allAttrs := append([]attribute.KeyValue{
@@ -466,6 +487,25 @@ func RecordGatewayStart(ctx context.Context, transportMode string) {
 		))
 }
 
+func RecordInitialize(ctx context.Context, params *mcp.InitializeParams) {
+	if InitializeCounter == nil {
+		if os.Getenv("DOCKER_MCP_TELEMETRY_DEBUG") != "" {
+			fmt.Fprintf(os.Stderr, "[MCP-TELEMETRY] WARNING: InitializeCounter is nil - metrics not initialized\n")
+		}
+		return // Telemetry not initialized
+	}
+
+	if os.Getenv("DOCKER_MCP_TELEMETRY_DEBUG") != "" {
+		fmt.Fprintf(os.Stderr, "[MCP-TELEMETRY] Initialize called - adding to counter\n")
+	}
+
+	InitializeCounter.Add(ctx, 1,
+		metric.WithAttributes(
+			attribute.String("mcp.client.name", params.ClientInfo.Name),
+			attribute.String("mcp.client.version", params.ClientInfo.Version),
+		))
+}
+
 // RecordListTools records a list tools call
 func RecordListTools(ctx context.Context) {
 	if ListToolsCounter == nil {

cmd/docker-mcp/internal/telemetry/telemetry_test.go

@@ -174,6 +174,44 @@ func TestInitialization(t *testing.T) {
 	})
 }
 
+func TestStartInitializeSpan(t *testing.T) {
+	spanRecorder, _ := setupTestTelemetry(t)
+	Init()
+
+	ctx := context.Background()
+	clientName := "claude-ai"
+	clientVersion := "1.0.0"
+
+	// Start a tool call span
+	newCtx, span := StartInitializeSpan(ctx,
+		attribute.String("mcp.client.name", clientName),
+		attribute.String("mcp.client.version", clientVersion),
+	)
+
+	// Verify context was updated
+	assert.NotEqual(t, ctx, newCtx, "should return new context with span")
+
+	// End the span
+	span.End()
+
+	// Verify span attributes
+	spans := spanRecorder.Ended()
+	require.Len(t, spans, 1)
+
+	recordedSpan := spans[0]
+	assert.Equal(t, "mcp.initialize", recordedSpan.Name())
+
+	// Check attributes
+	attrs := recordedSpan.Attributes()
+	attrMap := make(map[string]string)
+	for _, attr := range attrs {
+		attrMap[string(attr.Key)] = attr.Value.AsString()
+	}
+
+	assert.Equal(t, clientName, attrMap["mcp.client.name"])
+	assert.Equal(t, clientVersion, attrMap["mcp.client.version"])
+}
+
 func TestStartToolCallSpan(t *testing.T) {
 	spanRecorder, _ := setupTestTelemetry(t)
 	Init()

docs/telemetry/README.md

@@ -54,6 +54,7 @@ AI Client (e.g., Claude Code)
 
 #### Startup and Lifecycle
 - **`mcp.gateway.starts`** - Records when the gateway starts, including transport mode (stdio/sse/streaming)
+- **`mcp.initialize`** - Records when the host initializes a connection with the gateway
 
 #### Discovery Operations
 When the gateway connects to MCP servers, it discovers their capabilities:
@@ -115,6 +116,10 @@ All metrics include contextual attributes for filtering and aggregation:
 - **`mcp.server.name`** - Name of the MCP server handling the operation
 - **`mcp.server.type`** - Type of server (docker, stdio, sse, unknown)
 
+### Initialize Attributes
+- **`mcp.client.name`** - Name of the connecting client (e.g. `claude-ai`)
+- **`mcp.client.version`** - Version of the connecting client (e.g. `0.1.0`)
+
 ### Operation-Specific Attributes
 - **`mcp.tool.name`** - Name of the tool being called
 - **`mcp.prompt.name`** - Name of the prompt being retrieved

go.mod

@@ -17,6 +17,8 @@ require (
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/mikefarah/yq/v4 v4.45.4
 	github.com/modelcontextprotocol/go-sdk v0.2.0
+	github.com/opencontainers/go-digest v1.0.0
+	github.com/opencontainers/image-spec v1.1.1
 	github.com/pkg/errors v0.9.1
 	github.com/sigstore/cosign/v2 v2.5.0
 	github.com/sigstore/sigstore v1.9.5
@@ -113,8 +115,6 @@ require (
 	github.com/oklog/ulid v1.3.1 // indirect
 	github.com/onsi/gomega v1.37.0 // indirect
 	github.com/open-policy-agent/opa v1.5.1 // indirect
-	github.com/opencontainers/go-digest v1.0.0 // indirect
-	github.com/opencontainers/image-spec v1.1.1 // indirect
 	github.com/opentracing/opentracing-go v1.2.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect