Support breakpoint debugger integrated to IDEs

This commit adds the IDE-integrated breakpoint debugger based on walker.
Now buildx provides DAP (Debug Adapter Protocol) API to IDEs so DAP-aware IDEs
can call buildx and allow users to perform breakpoint-based debugging on the
IDE's UI/UX.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

commands/dap.go

@@ -0,0 +1,56 @@
+package commands
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/docker/buildx/monitor/dap"
+	"github.com/docker/cli/cli/command"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+func addDAPCommands(cmd *cobra.Command, dockerCli command.Cli) {
+	cmd.AddCommand(
+		dapCmd(dockerCli),
+		attachContainerCmd(dockerCli),
+	)
+}
+
+func dapCmd(dockerCli command.Cli) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:    "dap",
+		Hidden: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			logrus.SetOutput(os.Stderr)
+			s, err := dap.NewServer(dockerCli, os.Stdin, os.Stdout)
+			if err != nil {
+				return err
+			}
+			if err := s.Serve(); err != nil {
+				logrus.WithError(err).Warnf("failed to serve")
+			}
+			logrus.Info("finishing server")
+			return nil
+		},
+	}
+	return cmd
+}
+
+func attachContainerCmd(dockerCli command.Cli) *cobra.Command {
+	var setTtyRaw bool
+	cmd := &cobra.Command{
+		Use:    fmt.Sprintf("%s [OPTIONS] rootdir", dap.AttachContainerCommand),
+		Hidden: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) < 1 || args[0] == "" {
+				return errors.Errorf("specify root dir: %+v", args)
+			}
+			return dap.AttachContainerIO(args[0], os.Stdin, os.Stdout, os.Stderr, setTtyRaw)
+		},
+	}
+	flags := cmd.Flags()
+	flags.BoolVar(&setTtyRaw, "set-tty-raw", false, "set tty raw")
+	return cmd
+}

commands/root.go

@@ -100,6 +100,7 @@ func addCommands(cmd *cobra.Command, dockerCli command.Cli) {
 		"builder",
 		completion.BuilderNames(dockerCli),
 	)
+	addDAPCommands(cmd, dockerCli) // hidden command; we need it for emacs DAP support
 }
 
 func rootFlags(options *rootOptions, flags *pflag.FlagSet) {