opentracing support

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

cmd/dagger/cmd/compute.go

@@ -3,11 +3,9 @@ package cmd
 import (
 	"fmt"
 
-	"dagger.io/go/cmd/dagger/logger"
 	"dagger.io/go/dagger"
 
-	"github.com/moby/buildkit/util/appcontext"
-
+	"github.com/rs/zerolog/log"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -29,8 +27,8 @@ var computeCmd = &cobra.Command{
 		}
 	},
 	Run: func(cmd *cobra.Command, args []string) {
-		lg := logger.New()
-		ctx := lg.WithContext(appcontext.Context())
+		ctx := cmd.Context()
+		lg := log.Ctx(ctx)
 
 		env, err := dagger.NewEnv()
 		if err != nil {

cmd/dagger/cmd/root.go

@@ -1,9 +1,13 @@
 package cmd
 
 import (
+	"os"
 	"strings"
 
 	"dagger.io/go/cmd/dagger/logger"
+	"github.com/moby/buildkit/util/appcontext"
+	"github.com/opentracing/opentracing-go"
+	otlog "github.com/opentracing/opentracing-go/log"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -39,9 +43,27 @@ func init() {
 }
 
 func Execute() {
-	lg := logger.New()
+	var (
+		lg  = logger.New()
+		ctx = lg.WithContext(appcontext.Context())
 
-	if err := rootCmd.Execute(); err != nil {
+		closer = logger.InitTracing()
+		span   opentracing.Span
+	)
+
+	if len(os.Args) > 1 {
+		span, ctx = opentracing.StartSpanFromContext(ctx, os.Args[1])
+		span.LogFields(otlog.String("command", strings.Join(os.Args, " ")))
+	}
+
+	defer func() {
+		if span != nil {
+			span.Finish()
+		}
+		closer.Close()
+	}()
+
+	if err := rootCmd.ExecuteContext(ctx); err != nil {
 		lg.Fatal().Err(err).Msg("failed to execute command")
 	}
 }

cmd/dagger/logger/tracer.go

@@ -0,0 +1,36 @@
+package logger
+
+import (
+	"io"
+	"os"
+
+	opentracing "github.com/opentracing/opentracing-go"
+	jaeger "github.com/uber/jaeger-client-go"
+)
+
+func InitTracing() io.Closer {
+	traceAddr := os.Getenv("JAEGER_TRACE")
+	if traceAddr == "" {
+		return &nopCloser{}
+	}
+
+	tr, err := jaeger.NewUDPTransport(traceAddr, 0)
+	if err != nil {
+		panic(err)
+	}
+
+	tracer, closer := jaeger.NewTracer(
+		"dagger",
+		jaeger.NewConstSampler(true),
+		jaeger.NewRemoteReporter(tr),
+	)
+	opentracing.SetGlobalTracer(tracer)
+	return closer
+}
+
+type nopCloser struct {
+}
+
+func (*nopCloser) Close() error {
+	return nil
+}