feat(go): add tracing (#768)

Author: Proximyst

cmd/config/cmd.go

@@ -3,6 +3,7 @@ package healthcheck
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"strings"
 
@@ -55,5 +56,6 @@ func run(ctx context.Context, c *cli.Command) error {
 		return fmt.Errorf("health check request returned non-2xx status code: %d", resp.StatusCode)
 	}
 
+	slog.InfoContext(ctx, "OK")
 	return nil
 }

cmd/healthcheck/cmd.go

@@ -10,6 +10,7 @@ import (
 	"github.com/grafana/grafana-image-renderer/cmd/server"
 	"github.com/grafana/grafana-image-renderer/pkg/service"
 	"github.com/urfave/cli/v3"
+	"go.opentelemetry.io/otel/trace"
 )
 
 func NewRootCmd() *cli.Command {
@@ -45,14 +46,42 @@ func NewRootCmd() *cli.Command {
 			default:
 				return ctx, fmt.Errorf("invalid log level: %s", c.String("log-level"))
 			}
-			slog.SetDefault(slog.New(slog.NewTextHandler(c.Writer, &slog.HandlerOptions{AddSource: true, Level: leveler})))
+			slog.SetDefault(slog.New(
+				&traceLogger{
+					underlying: slog.NewTextHandler(c.Writer, &slog.HandlerOptions{AddSource: true, Level: leveler}),
+				},
+			))
 
 			return ctx, nil
 		},
 		Commands: []*cli.Command{
-			config.NewCmd(),
 			healthcheck.NewCmd(),
 			server.NewCmd(),
 		},
 	}
 }
+
+var _ slog.Handler = (*traceLogger)(nil)
+
+type traceLogger struct {
+	underlying slog.Handler
+}
+
+func (t *traceLogger) Enabled(ctx context.Context, level slog.Level) bool {
+	return t.underlying.Enabled(ctx, level)
+}
+
+func (t *traceLogger) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &traceLogger{underlying: t.underlying.WithAttrs(attrs)}
+}
+
+func (t *traceLogger) WithGroup(name string) slog.Handler {
+	return &traceLogger{underlying: t.underlying.WithGroup(name)}
+}
+
+func (t *traceLogger) Handle(ctx context.Context, record slog.Record) error {
+	if sc := trace.SpanContextFromContext(ctx); sc.HasTraceID() {
+		record.AddAttrs(slog.String("trace_id", sc.TraceID().String()))
+	}
+	return t.underlying.Handle(ctx, record)
+}

cmd/root.go

@@ -3,31 +3,34 @@ package server
 import (
 	"context"
 	"fmt"
+	"slices"
 
 	"github.com/grafana/grafana-image-renderer/cmd/config"
 	"github.com/grafana/grafana-image-renderer/pkg/api"
 	"github.com/grafana/grafana-image-renderer/pkg/metrics"
 	"github.com/grafana/grafana-image-renderer/pkg/service"
+	"github.com/grafana/grafana-image-renderer/pkg/traces"
 	"github.com/urfave/cli/v3"
+	"go.opentelemetry.io/otel"
 )
 
 func NewCmd() *cli.Command {
 	return &cli.Command{
 		Name:  "server",
 		Usage: "Run the server part of the service.",
-		Flags: []cli.Flag{
+		Flags: slices.Concat([]cli.Flag{
 			&cli.StringFlag{
 				Name:     "addr",
 				Usage:    "The address to listen on for HTTP requests.",
 				Category: "Server",
 				Value:    ":8081",
 				Sources:  config.FromConfig("server.addr"),
 			},
-			&cli.StringFlag{
+			&cli.StringSliceFlag{
 				Name:     "auth-token",
-				Usage:    "The X-Auth-Token header value that must be sent to the service to permit requests.",
+				Usage:    "The X-Auth-Token header value that must be sent to the service to permit requests. May be repeated.",
 				Category: "Server",
-				Value:    "-",
+				Value:    []string{"-"},
 				Sources:  config.FromConfig("auth.token"),
 			},
 
@@ -51,18 +54,27 @@ func NewCmd() *cli.Command {
 				Category: "Browser",
 				Sources:  config.FromConfig("browser.gpu"),
 			},
-		},
+		}, traces.TracerFlags()),
 		Action: run,
 	}
 }
 
 func run(ctx context.Context, c *cli.Command) error {
 	metrics := metrics.NewRegistry()
+	tracerProvider, err := traces.NewTracerProvider(ctx, c)
+	if err != nil {
+		return fmt.Errorf("failed to set up tracer: %w", err)
+	}
+	if tracerProvider != nil {
+		defer func() { _ = tracerProvider.Shutdown(ctx) }()
+		ctx = traces.WithTracerProvider(ctx, tracerProvider)
+		otel.SetTracerProvider(tracerProvider)
+	}
 	browser := service.NewBrowserService(c.String("browser"), c.StringSlice("browser-flags"),
 		service.WithViewport(1000, 500),
 		service.WithGPU(c.Bool("browser-gpu")))
 	versions := service.NewVersionService()
-	handler, err := api.NewHandler(metrics, browser, api.AuthToken(c.String("auth-token")), versions)
+	handler, err := api.NewHandler(metrics, browser, api.AuthTokens(c.StringSlice("auth-token")), versions)
 	if err != nil {
 		return fmt.Errorf("failed to create API handler: %w", err)
 	}

cmd/server/cmd.go

@@ -0,0 +1,3 @@
+This intends on setting up a FULL dev environment, including all supporting services, such that you can develop the Go backend easily.
+
+To restart and build the docker image again, do `docker compose up -d --build`

devenv/docker/enterprise-host/docker-compose.yaml

@@ -0,0 +1,10 @@
+apiVersion: 1
+
+providers:
+  - name: go-build
+    folder: DevEnv go-build dashboards
+    type: file
+    allowUiUpdates: false
+    updateIntervalSeconds: 60
+    options:
+      path: dashboards