Update system prune flag --all confirmation prompt

cmd/nerdctl/system_prune.go

@@ -23,7 +23,6 @@ import (
 	"github.com/containerd/nerdctl/pkg/api/types"
 	"github.com/containerd/nerdctl/pkg/clientutil"
 	"github.com/containerd/nerdctl/pkg/cmd/system"
-	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
 
@@ -80,12 +79,6 @@ func grantSystemPrunePermission(cmd *cobra.Command, options types.SystemPruneOpt
 		return false, err
 	}
 
-	if !options.All {
-		logrus.Warn("Currently, `nerdctl system prune` requires --all to be specified. Skip pruning.")
-		// NOP
-		return false, nil
-	}
-
 	if !force {
 		var confirm string
 		msg := `This will remove:
@@ -95,10 +88,16 @@ func grantSystemPrunePermission(cmd *cobra.Command, options types.SystemPruneOpt
 			msg += `
   - all volumes not used by at least one container`
 		}
-		msg += `
+		if options.All {
+			msg += `
   - all images without at least one container associated to them
-  - all build cache
-`
+  - all build cache`
+		} else {
+			msg += `
+  - all dangling images
+  - all dangling build cache`
+		}
+
 		msg += "\nAre you sure you want to continue? [y/N] "
 		fmt.Fprintf(options.Stdout, "WARNING! %s", msg)
 		fmt.Fscanf(cmd.InOrStdin(), "%s", &confirm)

pkg/api/types/builder_types.go

@@ -63,13 +63,13 @@ type BuilderBuildOptions struct {
 	BuildContext string
 }
 
-// BuilderPruneOptions specifies options for `nerdctl builder build`.
+// BuilderPruneOptions specifies options for `nerdctl builder prune`.
 type BuilderPruneOptions struct {
 	Stderr io.Writer
 	// GOptions is the global options
 	GOptions GlobalCommandOptions
 	// BuildKitHost is the buildkit host
 	BuildKitHost string
-	// All will remove all unused build cache, not just dangling ones
+	// All will remove all unused images and all build cache, not just dangling ones
 	All bool
 }

pkg/cmd/system/prune.go

@@ -57,7 +57,7 @@ func Prune(ctx context.Context, client *containerd.Client, options types.SystemP
 	if err := image.Prune(ctx, client, types.ImagePruneOptions{
 		Stdout:   options.Stdout,
 		GOptions: options.GOptions,
-		All:      true,
+		All:      options.All,
 	}); err != nil {
 		return nil
 	}