Merge pull request #886 from yifan-gu/img_cat

rkt/image: Add cat-manifest to print the image manifest to stdout.

rkt/help.go

@@ -34,9 +34,10 @@ var (
 	}
 	helpFlags flag.FlagSet
 
-	globalUsageTemplate  *template.Template
-	commandUsageTemplate *template.Template
-	templFuncs           = template.FuncMap{
+	globalUsageTemplate     *template.Template
+	commandUsageTemplate    *template.Template
+	subCommandUsageTemplate *template.Template
+	templFuncs              = template.FuncMap{
 		"descToLines": func(s string) []string {
 			// trim leading/trailing whitespace and split into slice of lines
 			return strings.Split(strings.Trim(s, "\n\t "), "\n")
@@ -86,6 +87,20 @@ DESCRIPTION:
 {{printOption .Name .DefValue .Usage}}{{end}}
 
 {{end}}For help on global options run "{{.Executable}} help"
+`[1:]))
+	subCommandUsageTemplate = template.Must(template.New("subcommand_usage").Funcs(templFuncs).Parse(`
+NAME:
+{{printf "\t%s %s - %s" .CmdName .SubCmd.Name .SubCmd.Summary}}
+
+USAGE:
+{{printf "\t%s %s %s %s" .Executable .CmdName .SubCmd.Name .SubCmd.Usage}}
+
+DESCRIPTION:
+{{range $line := descToLines .SubCmd.Description}}{{printf "\t%s" $line}}
+{{end}}
+{{if .SubCmdFlags}}OPTIONS:{{range .SubCmdFlags}}
+{{printOption .Name .DefValue .Usage}}{{end}}
+{{end}}
 `[1:]))
 }
 
@@ -95,7 +110,17 @@ func runHelp(args []string) (exit int) {
 		return
 	}
 
-	if err := printCommandUsageByName(args[0]); err != nil {
+	if len(args) == 1 {
+		if err := printCommandUsageByName(args[0]); err != nil {
+			printGlobalUsage()
+			stderr("\nHelp error: %v\n", err)
+			return 1
+		}
+		return
+	}
+
+	// Help for sub-commands.
+	if err := printSubCommandUsageByName(args[0], args[1], subCommands[args[0]]); err != nil {
 		printGlobalUsage()
 		stderr("\nHelp error: %v\n", err)
 		return 1
@@ -151,3 +176,37 @@ func printCommandUsageByName(name string) error {
 
 	return nil
 }
+
+func printSubCommandUsage(cmdName string, subCmd *Command) {
+	subCommandUsageTemplate.Execute(tabOut, struct {
+		Executable  string
+		CmdName     string
+		SubCmd      *Command
+		SubCmdFlags []*flag.Flag
+	}{
+		cliName,
+		cmdName,
+		subCmd,
+		getFlags(subCmd.Flags),
+	})
+	tabOut.Flush()
+}
+
+func printSubCommandUsageByName(name, subName string, subCommands []*Command) error {
+	var cmd *Command
+
+	for _, c := range subCommands {
+		if c.Name == subName {
+			cmd = c
+			break
+		}
+	}
+
+	if cmd == nil {
+		return fmt.Errorf("unrecognized sub-command: %s", subName)
+	}
+
+	printSubCommandUsage(name, cmd)
+
+	return nil
+}

rkt/image.go

@@ -0,0 +1,65 @@
+// Copyright 2015 The rkt Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"flag"
+	"os"
+)
+
+var (
+	cmdImage = &Command{
+		Name:    "image",
+		Summary: "Operate on an image in the local store",
+		Usage:   "SUBCOMMAND IMAGE [args...]",
+		Description: `SUBCOMMAND could be "cat-manifest". IMAGE should be a string referencing an image; either a hash, local file on disk, or URL.
+They will be checked in that order and the first match will be used.`,
+		Run:   runImage,
+		Flags: &imageFlags,
+	}
+	imageFlags flag.FlagSet
+)
+
+func init() {
+	commands = append(commands, cmdImage)
+}
+
+func runImage(args []string) (exit int) {
+	if len(args) < 1 {
+		printCommandUsageByName("image")
+		return 1
+	}
+
+	var subCmd *Command
+	subArgs := args[1:]
+
+	// determine which Command should be run
+	for _, c := range subCommands["image"] {
+		if c.Name == args[0] {
+			subCmd = c
+			if err := c.Flags.Parse(subArgs); err != nil {
+				stderr("%v", err)
+				os.Exit(2)
+			}
+			break
+		}
+	}
+
+	if subCmd == nil {
+		stderr("image: unknown subcommand: %q", args[0])
+		os.Exit(2)
+	}
+	return subCmd.Run(subArgs[subCmd.Flags.NFlag():])
+}

rkt/image_cat_manifest.go

@@ -0,0 +1,93 @@
+// Copyright 2015 The rkt Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"encoding/json"
+	"flag"
+
+	"github.com/coreos/rkt/store"
+)
+
+var (
+	cmdImageCatManifest = &Command{
+		Name:    "cat-manifest",
+		Summary: "Inspect and print the image manifest",
+		Usage:   "IMAGE",
+		Description: `IMAGE should be a string referencing an image; either a hash, local file on disk, or URL.
+They will be checked in that order and the first match will be used.`,
+		Run:   runImageCatManifest,
+		Flags: &imageCatManifestFlag,
+	}
+	imageCatManifestFlag flag.FlagSet
+	flagPrettyPrint      bool
+)
+
+func init() {
+	subCommands["image"] = append(subCommands["image"], cmdImageCatManifest)
+
+	imageCatManifestFlag.BoolVar(&flagPrettyPrint, "pretty-print", false, "apply indent to format the output")
+}
+
+func runImageCatManifest(args []string) (exit int) {
+	if len(args) != 1 {
+		printSubCommandUsageByName("image", "cat-manifest", subCommands["image"])
+		return 1
+	}
+
+	s, err := store.NewStore(globalFlags.Dir)
+	if err != nil {
+		stderr("image cat-manifest: cannot open store: %v\n", err)
+		return 1
+	}
+	ks := getKeystore()
+
+	fn := &finder{
+		imageActionData: imageActionData{
+			s:                  s,
+			ks:                 ks,
+			insecureSkipVerify: true,
+			debug:              globalFlags.Debug,
+		},
+		local:    true,
+		withDeps: false,
+	}
+
+	h, err := fn.findImage(args[0], "", true)
+	if err != nil {
+		stderr("image cat-manifest: cannot find image: %v\n", err)
+		return 1
+	}
+
+	manifest, err := fn.s.GetImageManifest(h.String())
+	if err != nil {
+		stderr("image cat-manifest: cannot get image manifest: %v\n", err)
+		return 1
+	}
+
+	var b []byte
+	if flagPrettyPrint {
+		b, err = json.MarshalIndent(manifest, "", "\t")
+	} else {
+		b, err = json.Marshal(manifest)
+	}
+	if err != nil {
+		stderr("image cat-manifest: cannot read the image manifest: %v\n", err)
+		return 1
+	}
+
+	stdout(string(b))
+	return 0
+}

rkt/rkt.go

@@ -40,6 +40,7 @@ var (
 	globalFlagset = flag.NewFlagSet(cliName, flag.ExitOnError)
 	tabOut        *tabwriter.Writer
 	commands      []*Command // Commands should register themselves by appending
+	subCommands   = make(map[string][]*Command)
 	globalFlags   = struct {
 		Dir                string
 		SystemConfigDir    string