Add some basic logging of config on startup when using stdio (#71)

* Add some basic logging of config on startup when using stdio

Closes #70.

* Still log address when using SSE transport

* Log redacted URLs

Author: sd2k

cmd/mcp-grafana/main.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"flag"
 	"fmt"
-	"log"
+	"log/slog"
 	"os"
 
 	"github.com/mark3labs/mcp-go/server"
@@ -29,19 +29,21 @@ func newServer() *server.MCPServer {
 	return s
 }
 
-func run(transport, addr string) error {
+func run(transport, addr string, logLevel slog.Level) error {
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel})))
 	s := newServer()
 
 	switch transport {
 	case "stdio":
 		srv := server.NewStdioServer(s)
 		srv.SetContextFunc(mcpgrafana.ComposedStdioContextFunc)
+		slog.Info("Starting Grafana MCP server using stdio transport")
 		return srv.Listen(context.Background(), os.Stdin, os.Stdout)
 	case "sse":
 		srv := server.NewSSEServer(s,
 			server.WithSSEContextFunc(mcpgrafana.ComposedSSEContextFunc),
 		)
-		log.Printf("SSE server listening on %s", addr)
+		slog.Info("Starting Grafana MCP server using SSE transport", "address", addr)
 		if err := srv.Start(addr); err != nil {
 			return fmt.Errorf("Server error: %v", err)
 		}
@@ -64,9 +66,18 @@ func main() {
 		"Transport type (stdio or sse)",
 	)
 	addr := flag.String("sse-address", "localhost:8000", "The host and port to start the sse server on")
+	logLevel := flag.String("log-level", "info", "Log level (debug, info, warn, error)")
 	flag.Parse()
 
-	if err := run(transport, *addr); err != nil {
+	if err := run(transport, *addr, parseLevel(*logLevel)); err != nil {
 		panic(err)
 	}
 }
+
+func parseLevel(level string) slog.Level {
+	var l slog.Level
+	if err := l.UnmarshalText([]byte(level)); err != nil {
+		return slog.LevelInfo
+	}
+	return l
+}

mcpgrafana.go

@@ -3,6 +3,7 @@ package mcpgrafana
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"net/url"
 	"os"
@@ -47,6 +48,11 @@ var ExtractGrafanaInfoFromEnv server.StdioContextFunc = func(ctx context.Context
 	if u == "" {
 		u = defaultGrafanaURL
 	}
+	parsedURL, err := url.Parse(u)
+	if err != nil {
+		panic(fmt.Errorf("invalid Grafana URL %s: %w", u, err))
+	}
+	slog.Info("Using Grafana configuration", "url", parsedURL.Redacted(), "api_key_set", apiKey != "")
 	return WithGrafanaURL(WithGrafanaAPIKey(ctx, apiKey), u)
 }
 
@@ -100,22 +106,31 @@ type grafanaClientKey struct{}
 var ExtractGrafanaClientFromEnv server.StdioContextFunc = func(ctx context.Context) context.Context {
 	cfg := client.DefaultTransportConfig()
 	// Extract transport config from env vars, and set it on the context.
-	if u, ok := os.LookupEnv(grafanaURLEnvVar); ok {
-		url, err := url.Parse(u)
+	var grafanaURL string
+	var parsedURL *url.URL
+	var ok bool
+	var err error
+	if grafanaURL, ok = os.LookupEnv(grafanaURLEnvVar); ok {
+		parsedURL, err = url.Parse(grafanaURL)
 		if err != nil {
 			panic(fmt.Errorf("invalid %s: %w", grafanaURLEnvVar, err))
 		}
-		cfg.Host = url.Host
+		cfg.Host = parsedURL.Host
 		// The Grafana client will always prefer HTTPS even if the URL is HTTP,
 		// so we need to limit the schemes to HTTP if the URL is HTTP.
-		if url.Scheme == "http" {
+		if parsedURL.Scheme == "http" {
 			cfg.Schemes = []string{"http"}
 		}
+	} else {
+		parsedURL, _ = url.Parse(defaultGrafanaURL)
 	}
-	if apiKey := os.Getenv(grafanaAPIEnvVar); apiKey != "" {
+
+	apiKey := os.Getenv(grafanaAPIEnvVar)
+	if apiKey != "" {
 		cfg.APIKey = apiKey
 	}
 
+	slog.Debug("Creating Grafana client", "url", parsedURL.Redacted(), "api_key_set", apiKey != "")
 	client := client.NewHTTPClientWithConfig(strfmt.Default, cfg)
 	return context.WithValue(ctx, grafanaClientKey{}, client)
 }
@@ -161,7 +176,15 @@ type incidentClientKey struct{}
 
 var ExtractIncidentClientFromEnv server.StdioContextFunc = func(ctx context.Context) context.Context {
 	grafanaURL, apiKey := urlAndAPIKeyFromEnv()
+	if grafanaURL == "" {
+		grafanaURL = defaultGrafanaURL
+	}
 	incidentURL := fmt.Sprintf("%s/api/plugins/grafana-incident-app/resources/api/v1/", grafanaURL)
+	parsedURL, err := url.Parse(incidentURL)
+	if err != nil {
+		panic(fmt.Errorf("invalid incident URL %s: %w", incidentURL, err))
+	}
+	slog.Debug("Creating Incident client", "url", parsedURL.Redacted(), "api_key_set", apiKey != "")
 	client := incident.NewClient(incidentURL, apiKey)
 	return context.WithValue(ctx, incidentClientKey{}, client)
 }