Add flags and subcommand

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

commands/build.go

@@ -18,6 +18,7 @@ import (
 	"github.com/docker/buildx/controller"
 	cbuild "github.com/docker/buildx/controller/build"
 	"github.com/docker/buildx/controller/control"
+	controllererrors "github.com/docker/buildx/controller/errdefs"
 	controllerapi "github.com/docker/buildx/controller/pb"
 	"github.com/docker/buildx/monitor"
 	"github.com/docker/buildx/store"
@@ -66,7 +67,8 @@ type buildOptions struct {
 	target         string
 	ulimits        *dockeropts.UlimitOpt
 
-	invoke string
+	invoke  *invokeConfig
+	noBuild bool
 
 	attests    []string
 	sbom       string
@@ -228,6 +230,7 @@ func runBuild(dockerCli command.Cli, in buildOptions) error {
 func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 	options := buildOptions{}
 	cFlags := &commonFlags{}
+	var invokeFlag string
 
 	cmd := &cobra.Command{
 		Use:     "build [OPTIONS] PATH | URL | -",
@@ -249,6 +252,14 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 			options.progress = cFlags.progress
 			cmd.Flags().VisitAll(checkWarnedFlags)
 			if isExperimental() {
+				if invokeFlag != "" {
+					invokeConfig, err := parseInvokeConfig(invokeFlag)
+					if err != nil {
+						return err
+					}
+					options.invoke = &invokeConfig
+					options.noBuild = invokeFlag == "debug-shell"
+				}
 				return launchControllerAndRunBuild(dockerCli, options)
 			}
 			return runBuild(dockerCli, options)
@@ -323,7 +334,7 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 	flags.StringVar(&options.provenance, "provenance", "", `Shortand for "--attest=type=provenance"`)
 
 	if isExperimental() {
-		flags.StringVar(&options.invoke, "invoke", "", "Invoke a command after the build [experimental]")
+		flags.StringVar(&invokeFlag, "invoke", "", "Invoke a command after the build [experimental]")
 		flags.StringVar(&options.Root, "root", "", "Specify root directory of server to connect [experimental]")
 		flags.BoolVar(&options.Detach, "detach", runtime.GOOS == "linux", "Detach buildx server (supported only on linux) [experimental]")
 		flags.StringVar(&options.ServerConfig, "server-config", "", "Specify buildx server config file (used only when launching new server) [experimental]")
@@ -485,18 +496,10 @@ func updateLastActivity(dockerCli command.Cli, ng *store.NodeGroup) error {
 func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) error {
 	ctx := context.TODO()
 
-	if options.invoke != "" && (options.dockerfileName == "-" || options.contextPath == "-") {
+	if options.invoke != nil && (options.dockerfileName == "-" || options.contextPath == "-") {
 		// stdin must be usable for monitor
 		return errors.Errorf("Dockerfile or context from stdin is not supported with invoke")
 	}
-	var invokeConfig controllerapi.InvokeConfig
-	if inv := options.invoke; inv != "" {
-		var err error
-		invokeConfig, err = parseInvokeConfig(inv)
-		if err != nil {
-			return err
-		}
-	}
 
 	c, err := controller.NewController(ctx, options.ControlOptions, dockerCli)
 	if err != nil {
@@ -508,15 +511,7 @@ func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) er
 		}
 	}()
 
-	f := ioset.NewSingleForwarder()
-	pr, pw := io.Pipe()
-	f.SetWriter(pw, func() io.WriteCloser {
-		pw.Close() // propagate EOF
-		logrus.Debug("propagating stdin close")
-		return nil
-	})
-	f.SetReader(os.Stdin)
-
+	// Start build
 	opts, err := options.toControllerOptions()
 	if err != nil {
 		return err
@@ -526,14 +521,6 @@ func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) er
 		return err
 	}
 
-	// Avoid leaving a stale file if we eventually fail
-	if options.imageIDFile != "" {
-		if err := os.Remove(options.imageIDFile); err != nil && !os.IsNotExist(err) {
-			return errors.Wrap(err, "removing image ID file")
-		}
-	}
-
-	// Start build
 	// NOTE: buildx server has the current working directory different from the client
 	// so we need to resolve paths to abosolute ones in the client.
 	optsP, err := resolvePaths(&opts)
@@ -541,30 +528,60 @@ func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) er
 		return err
 	}
 	opts = *optsP
-	ref, resp, err := c.Build(ctx, opts, pr, os.Stdout, os.Stderr, progress)
-	if err != nil {
-		return errors.Wrapf(err, "failed to build") // TODO: allow invoke even on error
-	}
-	if err := pw.Close(); err != nil {
-		logrus.Debug("failed to close stdin pipe writer")
-	}
-	if err := pr.Close(); err != nil {
-		logrus.Debug("failed to close stdin pipe reader")
-	}
 
-	if options.quiet {
-		fmt.Println(resp.ExporterResponse[exptypes.ExporterImageDigestKey])
-	}
-	if options.imageIDFile != "" {
-		dgst := resp.ExporterResponse[exptypes.ExporterImageDigestKey]
-		if v, ok := resp.ExporterResponse[exptypes.ExporterImageConfigDigestKey]; ok {
-			dgst = v
+	var ref string
+	var retErr error
+	f := ioset.NewSingleForwarder()
+	f.SetReader(os.Stdin)
+	if !options.noBuild {
+		pr, pw := io.Pipe()
+		f.SetWriter(pw, func() io.WriteCloser {
+			pw.Close() // propagate EOF
+			logrus.Debug("propagating stdin close")
+			return nil
+		})
+
+		// Avoid leaving a stale file if we eventually fail
+		if options.imageIDFile != "" {
+			if err := os.Remove(options.imageIDFile); err != nil && !os.IsNotExist(err) {
+				return errors.Wrap(err, "removing image ID file")
+			}
+		}
+
+		var resp *client.SolveResponse
+		ref, resp, err = c.Build(ctx, opts, pr, os.Stdout, os.Stderr, progress)
+		if err != nil {
+			var be *controllererrors.BuildError
+			if errors.As(err, &be) {
+				ref = be.Ref
+				retErr = err
+				// We can proceed to monitor
+			} else {
+				return errors.Wrapf(err, "failed to build")
+			}
+		}
+		if err := pw.Close(); err != nil {
+			logrus.Debug("failed to close stdin pipe writer")
+		}
+		if err := pr.Close(); err != nil {
+			logrus.Debug("failed to close stdin pipe reader")
 		}
-		return os.WriteFile(options.imageIDFile, []byte(dgst), 0644)
+
+		if options.quiet {
+			fmt.Println(resp.ExporterResponse[exptypes.ExporterImageDigestKey])
+		}
+		if options.imageIDFile != "" {
+			dgst := resp.ExporterResponse[exptypes.ExporterImageDigestKey]
+			if v, ok := resp.ExporterResponse[exptypes.ExporterImageConfigDigestKey]; ok {
+				dgst = v
+			}
+			return os.WriteFile(options.imageIDFile, []byte(dgst), 0644)
+		}
+
 	}
 
 	// post-build operations
-	if options.invoke != "" {
+	if options.invoke != nil && options.invoke.needsMonitor(retErr) {
 		pr2, pw2 := io.Pipe()
 		f.SetWriter(pw2, func() io.WriteCloser {
 			pw2.Close() // propagate EOF
@@ -577,7 +594,7 @@ func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) er
 			}
 			return errors.Errorf("failed to configure terminal: %v", err)
 		}
-		err = monitor.RunMonitor(ctx, ref, opts, invokeConfig, c, options.progress, pr2, os.Stdout, os.Stderr)
+		err = monitor.RunMonitor(ctx, ref, &opts, options.invoke.InvokeConfig, c, progress, pr2, os.Stdout, os.Stderr)
 		con.Reset()
 		if err := pw2.Close(); err != nil {
 			logrus.Debug("failed to close monitor stdin pipe reader")
@@ -593,9 +610,33 @@ func launchControllerAndRunBuild(dockerCli command.Cli, options buildOptions) er
 	return nil
 }
 
-func parseInvokeConfig(invoke string) (cfg controllerapi.InvokeConfig, err error) {
+type invokeConfig struct {
+	controllerapi.InvokeConfig
+	invokeFlag string
+}
+
+func (cfg *invokeConfig) needsMonitor(retErr error) bool {
+	switch cfg.invokeFlag {
+	case "debug-shell":
+		return true
+	case "on-error":
+		return retErr != nil
+	default:
+		return cfg.invokeFlag != ""
+	}
+}
+
+func parseInvokeConfig(invoke string) (cfg invokeConfig, err error) {
+	cfg.invokeFlag = invoke
 	cfg.Tty = true
-	if invoke == "default" {
+	switch invoke {
+	case "default", "debug-shell":
+		return cfg, nil
+	case "on-error":
+		// NOTE: we overwrite the command to run because the original one should fail on the failed step.
+		// TODO: make this configurable via flags or restorable from LLB.
+		// Discussion: https://github.com/docker/buildx/pull/1640#discussion_r1113295900
+		cfg.Cmd = []string{"/bin/sh"}
 		return cfg, nil
 	}
 

commands/debug-shell.go

@@ -0,0 +1,63 @@
+package commands
+
+import (
+	"context"
+	"os"
+	"runtime"
+
+	"github.com/containerd/console"
+	"github.com/docker/buildx/controller"
+	"github.com/docker/buildx/controller/control"
+	controllerapi "github.com/docker/buildx/controller/pb"
+	"github.com/docker/buildx/monitor"
+	"github.com/docker/cli/cli/command"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+func debugShellCmd(dockerCli command.Cli) *cobra.Command {
+	var options control.ControlOptions
+	var progress string
+
+	cmd := &cobra.Command{
+		Use:   "debug-shell",
+		Short: "Start a monitor",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			ctx := context.TODO()
+			c, err := controller.NewController(ctx, options, dockerCli)
+			if err != nil {
+				return err
+			}
+			defer func() {
+				if err := c.Close(); err != nil {
+					logrus.Warnf("failed to close server connection %v", err)
+				}
+			}()
+			con := console.Current()
+			if err := con.SetRaw(); err != nil {
+				return errors.Errorf("failed to configure terminal: %v", err)
+			}
+			err = monitor.RunMonitor(ctx, "", nil, controllerapi.InvokeConfig{
+				Tty: true,
+			}, c, progress, os.Stdin, os.Stdout, os.Stderr)
+			con.Reset()
+			return err
+		},
+	}
+
+	flags := cmd.Flags()
+
+	flags.StringVar(&options.Root, "root", "", "Specify root directory of server to connect [experimental]")
+	flags.BoolVar(&options.Detach, "detach", runtime.GOOS == "linux", "Detach buildx server (supported only on linux) [experimental]")
+	flags.StringVar(&options.ServerConfig, "server-config", "", "Specify buildx server config file (used only when launching new server) [experimental]")
+	flags.StringVar(&progress, "progress", "auto", `Set type of progress output ("auto", "plain", "tty"). Use plain to show container output`)
+
+	return cmd
+}
+
+func addDebugShellCommand(cmd *cobra.Command, dockerCli command.Cli) {
+	cmd.AddCommand(
+		debugShellCmd(dockerCli),
+	)
+}

commands/root.go

@@ -89,6 +89,7 @@ func addCommands(cmd *cobra.Command, dockerCli command.Cli) {
 	)
 	if isExperimental() {
 		remote.AddControllerCommands(cmd, dockerCli)
+		addDebugShellCommand(cmd, dockerCli)
 	}
 }
 

docs/reference/buildx.md

@@ -15,6 +15,7 @@ Extended build capabilities with BuildKit
 | [`bake`](buildx_bake.md)                       | Build from a file                          |
 | [`build`](buildx_build.md)                     | Start a build                              |
 | [`create`](buildx_create.md)                   | Create a new builder instance              |
+| [`debug-shell`](buildx_debug-shell.md)         | Start a monitor                            |
 | [`du`](buildx_du.md)                           | Disk usage                                 |
 | [`imagetools`](buildx_imagetools.md)           | Commands to work on images in registry     |
 | [`inspect`](buildx_inspect.md)                 | Inspect current builder instance           |

docs/reference/buildx_debug-shell.md

@@ -0,0 +1,18 @@
+# docker buildx debug-shell
+
+<!---MARKER_GEN_START-->
+Start a monitor
+
+### Options
+
+| Name              | Type     | Default | Description                                                                              |
+|:------------------|:---------|:--------|:-----------------------------------------------------------------------------------------|
+| `--builder`       | `string` |         | Override the configured builder instance                                                 |
+| `--detach`        |          |         | Detach buildx server (supported only on linux) [experimental]                            |
+| `--progress`      | `string` | `auto`  | Set type of progress output (`auto`, `plain`, `tty`). Use plain to show container output |
+| `--root`          | `string` |         | Specify root directory of server to connect [experimental]                               |
+| `--server-config` | `string` |         | Specify buildx server config file (used only when launching new server) [experimental]   |
+
+
+<!---MARKER_GEN_END-->
+