re-wire logging on top of zerolog

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

cmd/dagger/cmd/compute.go

@@ -1,37 +1,45 @@
 package cmd
 
 import (
-	"context"
 	"fmt"
 
-	"dagger.cloud/go/cmd/dagger/ui"
+	"dagger.cloud/go/cmd/dagger/logger"
 	"dagger.cloud/go/dagger"
+
+	"github.com/moby/buildkit/util/appcontext"
+
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
 var computeCmd = &cobra.Command{
 	Use:   "compute CONFIG",
 	Short: "Compute a configuration",
 	Args:  cobra.ExactArgs(1),
+	PreRun: func(cmd *cobra.Command, args []string) {
+		// Fix Viper bug for duplicate flags:
+		// https://github.com/spf13/viper/issues/233
+		if err := viper.BindPFlags(cmd.Flags()); err != nil {
+			panic(err)
+		}
+	},
 	Run: func(cmd *cobra.Command, args []string) {
-		ctx := context.TODO()
+		lg := logger.New()
+		ctx := lg.WithContext(appcontext.Context())
+
 		// FIXME: boot and bootdir should be config fields, not args
 		c, err := dagger.NewClient(ctx, "", "", args[0])
 		if err != nil {
-			ui.FatalErr(err)
+			lg.Fatal().Err(err).Msg("unable to create client")
 		}
 		// FIXME: configure which config to compute (duh)
 		// FIXME: configure inputs
-		ui.Info("Running")
+		lg.Info().Msg("running")
 		output, err := c.Compute(ctx)
 		if err != nil {
-			ui.FatalErr(err)
+			lg.Fatal().Err(err).Msg("failed to compute")
 		}
-		ui.Info("Processing output")
+		lg.Info().Msg("processing output")
 		fmt.Println(output.JSON())
 	},
 }
-
-func init() {
-	//	computeCmd.Flags().StringP("catalog", "c", "", "Cue package catalog")
-}

cmd/dagger/cmd/root.go

@@ -1,8 +1,11 @@
 package cmd
 
 import (
-	"dagger.cloud/go/cmd/dagger/ui"
+	"strings"
+
+	"dagger.cloud/go/cmd/dagger/logger"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
 var rootCmd = &cobra.Command{
@@ -11,9 +14,9 @@ var rootCmd = &cobra.Command{
 }
 
 func init() {
-	// --debug
-	rootCmd.PersistentFlags().Bool("debug", false, "Enable debug mode")
-	// --workspace
+	rootCmd.PersistentFlags().String("log-format", "", "Log format (json, pretty). Defaults to json if the terminal is not a tty")
+	rootCmd.PersistentFlags().StringP("log-level", "l", "debug", "Log level")
+
 	rootCmd.AddCommand(
 		computeCmd,
 		// Create an env
@@ -26,10 +29,19 @@ func init() {
 		//		computeCmd,
 		//		listCmd,
 	)
+
+	if err := viper.BindPFlags(rootCmd.PersistentFlags()); err != nil {
+		panic(err)
+	}
+	viper.SetEnvPrefix("dagger")
+	viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
+	viper.AutomaticEnv()
 }
 
 func Execute() {
+	lg := logger.New()
+
 	if err := rootCmd.Execute(); err != nil {
-		ui.FatalErr(err)
+		lg.Fatal().Err(err).Msg("failed to execute command")
 	}
 }

cmd/dagger/logger/logger.go

@@ -0,0 +1,51 @@
+// Logger utilities for the CLI
+//
+// These utilities rely on command line flags to set up the logger, therefore
+// they are tightly coupled with the CLI and should not be used outside.
+
+package logger
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/rs/zerolog"
+	"github.com/spf13/viper"
+	"golang.org/x/term"
+)
+
+func New() zerolog.Logger {
+	logger := zerolog.
+		New(os.Stderr).
+		With().
+		Timestamp().
+		Logger()
+
+	if prettyLogs() {
+		logger = logger.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+	} else {
+		logger = logger.With().Timestamp().Caller().Logger()
+	}
+
+	level := viper.GetString("log-level")
+	lvl, err := zerolog.ParseLevel(level)
+	if err != nil {
+		panic(err)
+	}
+	return logger.Level(lvl)
+}
+
+func prettyLogs() bool {
+	switch f := viper.GetString("log-format"); f {
+	case "json":
+		return false
+	case "pretty":
+		return true
+	case "":
+		return term.IsTerminal(int(os.Stdout.Fd()))
+	default:
+		fmt.Fprintf(os.Stderr, "invalid --log-format %q\n", f)
+		os.Exit(1)
+	}
+	return false
+}