api/services/instrospection: add PluginInfo

The new `PlunginInfo()` call can be used for instrospecting the details
of the runtime plugin.

```console
$ ctr plugins inspect-runtime --runtime=io.containerd.runc.v2 --runc-binary=runc
{
    "Name": "io.containerd.runc.v2",
    "Version": {
        "Version": "v2.0.0-beta.0-XX-gXXXXXXXXX.m",
        "Revision": "v2.0.0-beta.0-XX-gXXXXXXXXX.m"
    },
    "Options": {
        "binary_name": "runc"
    },
    "Features": {
        "ociVersionMin": "1.0.0",
        "ociVersionMax": "1.1.0-rc.2",
        ...,
    },
    "Annotations": null
}
```

The shim binary has to support `-info` flag, see `runtime/v2/README.md`

Replaces PR 8509 (`api/services/task: add RuntimeInfo()`)

Co-authored-by: Derek McGowan <derek@mcg.dev>
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

cmd/ctr/commands/commands.go

@@ -96,6 +96,19 @@ var (
 		},
 	}
 
+	// RuntimeFlags are cli flags specifying runtime
+	RuntimeFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "runtime",
+			Usage: "Runtime name or absolute path to runtime binary",
+			Value: defaults.DefaultRuntime,
+		},
+		cli.StringFlag{
+			Name:  "runtime-config-path",
+			Usage: "Optional runtime config path",
+		},
+	}
+
 	// ContainerFlags are cli flags specifying container options
 	ContainerFlags = []cli.Flag{
 		cli.StringFlag{
@@ -138,19 +151,10 @@ var (
 			Name:  "read-only",
 			Usage: "Set the containers filesystem as readonly",
 		},
-		cli.StringFlag{
-			Name:  "runtime",
-			Usage: "Runtime name or absolute path to runtime binary",
-			Value: defaults.DefaultRuntime,
-		},
 		cli.StringFlag{
 			Name:  "sandbox",
 			Usage: "Create the container in the given sandbox",
 		},
-		cli.StringFlag{
-			Name:  "runtime-config-path",
-			Usage: "Optional runtime config path",
-		},
 		cli.BoolFlag{
 			Name:  "tty,t",
 			Usage: "Allocate a TTY for the container",

cmd/ctr/commands/commands_unix.go

@@ -19,10 +19,24 @@
 package commands
 
 import (
+	"errors"
+
+	"github.com/containerd/containerd/v2/core/runtime/v2/runc/options"
+	runtimeoptions "github.com/containerd/containerd/v2/pkg/runtimeoptions/v1"
 	"github.com/urfave/cli"
 )
 
 func init() {
+	RuntimeFlags = append(RuntimeFlags, cli.StringFlag{
+		Name:  "runc-binary",
+		Usage: "Specify runc-compatible binary",
+	}, cli.StringFlag{
+		Name:  "runc-root",
+		Usage: "Specify runc-compatible root",
+	}, cli.BoolFlag{
+		Name:  "runc-systemd-cgroup",
+		Usage: "Start runc with systemd cgroup manager",
+	})
 	ContainerFlags = append(ContainerFlags, cli.BoolFlag{
 		Name:  "rootfs",
 		Usage: "Use custom rootfs that is not managed by containerd snapshotter",
@@ -44,3 +58,42 @@ func init() {
 		Usage: "File path to a device to add to the container; or a path to a directory tree of devices to add to the container",
 	})
 }
+
+func getRuncOptions(context *cli.Context) (*options.Options, error) {
+	runtimeOpts := &options.Options{}
+	if runcBinary := context.String("runc-binary"); runcBinary != "" {
+		runtimeOpts.BinaryName = runcBinary
+	}
+	if context.Bool("runc-systemd-cgroup") {
+		if context.String("cgroup") == "" {
+			// runc maps "machine.slice:foo:deadbeef" to "/machine.slice/foo-deadbeef.scope"
+			return nil, errors.New("option --runc-systemd-cgroup requires --cgroup to be set, e.g. \"machine.slice:foo:deadbeef\"")
+		}
+		runtimeOpts.SystemdCgroup = true
+	}
+	if root := context.String("runc-root"); root != "" {
+		runtimeOpts.Root = root
+	}
+
+	return runtimeOpts, nil
+}
+
+func RuntimeOptions(context *cli.Context) (interface{}, error) {
+	// validate first
+	if (context.String("runc-binary") != "" || context.Bool("runc-systemd-cgroup")) &&
+		context.String("runtime") != "io.containerd.runc.v2" {
+		return nil, errors.New("specifying runc-binary and runc-systemd-cgroup is only supported for \"io.containerd.runc.v2\" runtime")
+	}
+
+	if context.String("runtime") == "io.containerd.runc.v2" {
+		return getRuncOptions(context)
+	}
+
+	if configPath := context.String("runtime-config-path"); configPath != "" {
+		return &runtimeoptions.Options{
+			ConfigPath: configPath,
+		}, nil
+	}
+
+	return nil, nil
+}

cmd/ctr/commands/commands_windows.go

@@ -38,3 +38,7 @@ func init() {
 			Usage: "Identifier of a device to add to the container  (e.g. class://5B45201D-F2F2-4F3B-85BB-30FF1F953599)",
 		})
 }
+
+func RuntimeOptions(context *cli.Context) (interface{}, error) {
+	return nil, nil
+}

cmd/ctr/commands/containers/containers.go

@@ -55,7 +55,7 @@ var createCommand = cli.Command{
 	Usage:          "Create container",
 	ArgsUsage:      "[flags] Image|RootFS CONTAINER [COMMAND] [ARG...]",
 	SkipArgReorder: true,
-	Flags:          append(append(commands.SnapshotterFlags, []cli.Flag{commands.SnapshotterLabels}...), commands.ContainerFlags...),
+	Flags:          append(commands.RuntimeFlags, append(append(commands.SnapshotterFlags, []cli.Flag{commands.SnapshotterLabels}...), commands.ContainerFlags...)...),
 	Action: func(context *cli.Context) error {
 		var (
 			id     string

cmd/ctr/commands/plugins/plugins.go

@@ -17,6 +17,7 @@
 package plugins
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"sort"
@@ -39,6 +40,7 @@ var Command = cli.Command{
 	Usage:   "Provides information about containerd plugins",
 	Subcommands: []cli.Command{
 		listCommand,
+		inspectRuntimeCommand,
 	},
 }
 
@@ -162,3 +164,32 @@ func prettyPlatforms(pspb []*types.Platform) string {
 	sort.Stable(sort.StringSlice(ps))
 	return strings.Join(ps, ",")
 }
+
+var inspectRuntimeCommand = cli.Command{
+	Name:      "inspect-runtime",
+	Usage:     "Display runtime info",
+	ArgsUsage: "[flags]",
+	Flags:     commands.RuntimeFlags,
+	Action: func(context *cli.Context) error {
+		rt := context.String("runtime")
+		rtOptions, err := commands.RuntimeOptions(context)
+		if err != nil {
+			return err
+		}
+		client, ctx, cancel, err := commands.NewClient(context)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+		rtInfo, err := client.RuntimeInfo(ctx, rt, rtOptions)
+		if err != nil {
+			return err
+		}
+		j, err := json.MarshalIndent(rtInfo, "", "    ")
+		if err != nil {
+			return err
+		}
+		_, err = fmt.Fprintln(context.App.Writer, string(j))
+		return err
+	},
+}

cmd/ctr/commands/run/run.go

@@ -128,8 +128,9 @@ var Command = cli.Command{
 			Usage: "Enable cni networking for the container",
 		},
 	}, append(platformRunFlags,
-		append(append(commands.SnapshotterFlags, []cli.Flag{commands.SnapshotterLabels}...),
-			commands.ContainerFlags...)...)...),
+		append(commands.RuntimeFlags,
+			append(append(commands.SnapshotterFlags, []cli.Flag{commands.SnapshotterLabels}...),
+				commands.ContainerFlags...)...)...)...),
 	Action: func(context *cli.Context) error {
 		var (
 			err error

cmd/ctr/commands/run/run_unix.go

@@ -34,10 +34,8 @@ import (
 	"github.com/containerd/containerd/v2/contrib/nvidia"
 	"github.com/containerd/containerd/v2/contrib/seccomp"
 	"github.com/containerd/containerd/v2/core/containers"
-	"github.com/containerd/containerd/v2/core/runtime/v2/runc/options"
 	"github.com/containerd/containerd/v2/core/snapshots"
 	"github.com/containerd/containerd/v2/pkg/oci"
-	runtimeoptions "github.com/containerd/containerd/v2/pkg/runtimeoptions/v1"
 	"github.com/containerd/log"
 	"github.com/containerd/platforms"
 	"github.com/intel/goresctrl/pkg/blockio"
@@ -48,18 +46,6 @@ import (
 )
 
 var platformRunFlags = []cli.Flag{
-	cli.StringFlag{
-		Name:  "runc-binary",
-		Usage: "Specify runc-compatible binary",
-	},
-	cli.StringFlag{
-		Name:  "runc-root",
-		Usage: "Specify runc-compatible root",
-	},
-	cli.BoolFlag{
-		Name:  "runc-systemd-cgroup",
-		Usage: "Start runc with systemd cgroup manager",
-	},
 	cli.StringFlag{
 		Name:  "uidmap",
 		Usage: "Run inside a user namespace with the specified UID mapping range; specified with the format `container-uid:host-uid:length`",
@@ -413,7 +399,7 @@ func NewContainer(ctx gocontext.Context, client *containerd.Client, context *cli
 		cOpts = append(cOpts, containerd.WithContainerExtension(commands.CtrCniMetadataExtension, cniMeta))
 	}
 
-	runtimeOpts, err := getRuntimeOptions(context)
+	runtimeOpts, err := commands.RuntimeOptions(context)
 	if err != nil {
 		return nil, err
 	}
@@ -430,45 +416,6 @@ func NewContainer(ctx gocontext.Context, client *containerd.Client, context *cli
 	return client.NewContainer(ctx, id, cOpts...)
 }
 
-func getRuncOptions(context *cli.Context) (*options.Options, error) {
-	runtimeOpts := &options.Options{}
-	if runcBinary := context.String("runc-binary"); runcBinary != "" {
-		runtimeOpts.BinaryName = runcBinary
-	}
-	if context.Bool("runc-systemd-cgroup") {
-		if context.String("cgroup") == "" {
-			// runc maps "machine.slice:foo:deadbeef" to "/machine.slice/foo-deadbeef.scope"
-			return nil, errors.New("option --runc-systemd-cgroup requires --cgroup to be set, e.g. \"machine.slice:foo:deadbeef\"")
-		}
-		runtimeOpts.SystemdCgroup = true
-	}
-	if root := context.String("runc-root"); root != "" {
-		runtimeOpts.Root = root
-	}
-
-	return runtimeOpts, nil
-}
-
-func getRuntimeOptions(context *cli.Context) (interface{}, error) {
-	// validate first
-	if (context.String("runc-binary") != "" || context.Bool("runc-systemd-cgroup")) &&
-		context.String("runtime") != "io.containerd.runc.v2" {
-		return nil, errors.New("specifying runc-binary and runc-systemd-cgroup is only supported for \"io.containerd.runc.v2\" runtime")
-	}
-
-	if context.String("runtime") == "io.containerd.runc.v2" {
-		return getRuncOptions(context)
-	}
-
-	if configPath := context.String("runtime-config-path"); configPath != "" {
-		return &runtimeoptions.Options{
-			ConfigPath: configPath,
-		}, nil
-	}
-
-	return nil, nil
-}
-
 func parseIDMapping(mapping string) (specs.LinuxIDMapping, error) {
 	// We expect 3 parts, but limit to 4 to allow detection of invalid values.
 	parts := strings.SplitN(mapping, ":", 4)