feat(mcp): scaffold mcp-telemetry server with metrics query tool (#262)

Author: victoriacheng15

cmd/mcp-telemetry/main.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"context"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"observability-hub/internal/env"
+	"observability-hub/internal/mcp/providers"
+	"observability-hub/internal/telemetry"
+)
+
+const serviceName = "mcp.telemetry"
+
+func main() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	env.Load()
+
+	if shutdown, err := telemetry.Init(ctx, serviceName); err != nil {
+		telemetry.Error("failed to init telemetry", "error", err)
+	} else {
+		defer shutdown()
+	}
+
+	thanosURL := os.Getenv("THANOS_URL")
+	lokiURL := os.Getenv("LOKI_URL")
+	tempoURL := os.Getenv("TEMPO_URL")
+
+	if thanosURL == "" {
+		telemetry.Error("THANOS_URL not set")
+		os.Exit(1)
+	}
+
+	provider := providers.NewTelemetryProvider(thanosURL)
+	telemetry.Info("MCP Telemetry server initialized", "thanos_url", thanosURL, "loki_url", lokiURL, "tempo_url", tempoURL)
+
+	server := mcp.NewServer(&mcp.Implementation{
+		Name:    "mcp-telemetry",
+		Version: "1.0.0",
+	}, nil)
+
+	registerTools(server, provider)
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
+	go func() {
+		t := &mcp.StdioTransport{}
+		if err := server.Run(ctx, t); err != nil {
+			telemetry.Error("MCP server stopped", "error", err)
+		}
+	}()
+
+	telemetry.Info("mcp-telemetry ready", "tools", []string{"query_metrics", "query_logs", "query_traces"})
+
+	sig := <-sigChan
+	telemetry.Info("received signal, shutting down", "signal", sig.String())
+	cancel()
+	provider.Close()
+}

cmd/mcp-telemetry/tools.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"observability-hub/internal/mcp/providers"
+	"observability-hub/internal/mcp/tools"
+	"observability-hub/internal/telemetry"
+)
+
+func registerTools(server *mcp.Server, provider *providers.TelemetryProvider) {
+	mcp.AddTool(server, &mcp.Tool{
+		Name:        "query_metrics",
+		Description: "Execute PromQL queries against Thanos/Prometheus for metrics analysis",
+	}, handleQueryMetrics(provider))
+
+	mcp.AddTool(server, &mcp.Tool{
+		Name:        "query_logs",
+		Description: "Execute LogQL queries against Loki for log analysis",
+	}, handleQueryLogs(provider))
+
+	mcp.AddTool(server, &mcp.Tool{
+		Name:        "query_traces",
+		Description: "Retrieve distributed traces from Tempo by trace ID",
+	}, handleQueryTraces(provider))
+
+	telemetry.Info("registered tools", "count", 3)
+}
+
+func handleQueryMetrics(provider *providers.TelemetryProvider) mcp.ToolHandlerFor[tools.QueryMetricsInput, any] {
+	handler := tools.NewQueryMetricsHandler(provider.QueryMetrics)
+	return func(ctx context.Context, _ *mcp.CallToolRequest, input tools.QueryMetricsInput) (*mcp.CallToolResult, any, error) {
+		result, err := handler.Execute(ctx, input)
+		if err != nil {
+			return nil, nil, err
+		}
+		text, _ := json.Marshal(result)
+		return &mcp.CallToolResult{
+			Content: []mcp.Content{&mcp.TextContent{Text: string(text)}},
+		}, nil, nil
+	}
+}
+
+func handleQueryLogs(provider *providers.TelemetryProvider) mcp.ToolHandlerFor[tools.QueryLogsInput, any] {
+	handler := tools.NewQueryLogsHandler(provider.QueryLogs)
+	return func(ctx context.Context, _ *mcp.CallToolRequest, input tools.QueryLogsInput) (*mcp.CallToolResult, any, error) {
+		result, err := handler.Execute(ctx, input)
+		if err != nil {
+			return nil, nil, err
+		}
+		text, _ := json.Marshal(result)
+		return &mcp.CallToolResult{
+			Content: []mcp.Content{&mcp.TextContent{Text: string(text)}},
+		}, nil, nil
+	}
+}
+
+func handleQueryTraces(provider *providers.TelemetryProvider) mcp.ToolHandlerFor[tools.QueryTracesInput, any] {
+	handler := tools.NewQueryTracesHandler(provider.QueryTraces)
+	return func(ctx context.Context, _ *mcp.CallToolRequest, input tools.QueryTracesInput) (*mcp.CallToolResult, any, error) {
+		result, err := handler.Execute(ctx, input)
+		if err != nil {
+			return nil, nil, err
+		}
+		text, _ := json.Marshal(result)
+		return &mcp.CallToolResult{
+			Content: []mcp.Content{&mcp.TextContent{Text: string(text)}},
+		}, nil, nil
+	}
+}