cmd/output: added support for listing outputs

Signed-off-by: Sam Alba <sam.alba@gmail.com>

cmd/dagger/cmd/output/list.go

@@ -0,0 +1,81 @@
+package output
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+	"text/tabwriter"
+
+	"go.dagger.io/dagger/client"
+	"go.dagger.io/dagger/cmd/dagger/cmd/common"
+	"go.dagger.io/dagger/cmd/dagger/logger"
+	"go.dagger.io/dagger/environment"
+	"go.dagger.io/dagger/solver"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+var listCmd = &cobra.Command{
+	Use:   "list [TARGET] [flags]",
+	Short: "List the outputs of an environment",
+	Args:  cobra.MaximumNArgs(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) {
+		lg := logger.New()
+		ctx := lg.WithContext(cmd.Context())
+
+		workspace := common.CurrentWorkspace(ctx)
+		st := common.CurrentEnvironmentState(ctx, workspace)
+
+		lg = lg.With().
+			Str("environment", st.Name).
+			Logger()
+
+		c, err := client.New(ctx, "", false)
+		if err != nil {
+			lg.Fatal().Err(err).Msg("unable to create client")
+		}
+
+		_, err = c.Do(ctx, st, func(ctx context.Context, env *environment.Environment, s solver.Solver) error {
+			outputs, err := env.ScanOutputs(ctx)
+			if err != nil {
+				return err
+			}
+
+			w := tabwriter.NewWriter(os.Stdout, 0, 4, 2, ' ', 0)
+			fmt.Fprintln(w, "Output\tType\tValue\tDescription")
+
+			for _, out := range outputs {
+				isConcrete := (out.IsConcreteR() == nil)
+				valStr := "-"
+				if isConcrete {
+					valStr, _ = out.Cue().String()
+				}
+
+				valStr = strings.ReplaceAll(valStr, "\n", "\\n")
+
+				fmt.Fprintf(w, "%s\t%s\t%s\t%s\n",
+					out.Path(),
+					common.ValueType(out),
+					valStr,
+					common.ValueDocString(out),
+				)
+			}
+
+			w.Flush()
+			return nil
+		})
+
+		if err != nil {
+			lg.Fatal().Err(err).Msg("failed to query environment")
+		}
+	},
+}

cmd/dagger/cmd/output/root.go

@@ -9,7 +9,6 @@ var Cmd = &cobra.Command{
 }
 
 func init() {
-	Cmd.AddCommand(
+	// Cmd.AddCommand(dirCmd)
-		dirCmd,
+	Cmd.AddCommand(listCmd)
-	)
 }