Add 'kpod pull' command

Signed-off-by: umohnani8 <umohnani@redhat.com>

cmd/kpod/common.go

@@ -1,7 +1,11 @@
 package main
 
 import (
+	"io"
+
+	cp "github.com/containers/image/copy"
 	is "github.com/containers/image/storage"
+	"github.com/containers/image/types"
 	"github.com/containers/storage"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
@@ -9,6 +13,11 @@ import (
 
 func getStore(c *cli.Context) (storage.Store, error) {
 	options := storage.DefaultStoreOptions
+	if c.GlobalIsSet("root") || c.GlobalIsSet("runroot") {
+		options.GraphRoot = c.GlobalString("root")
+		options.RunRoot = c.GlobalString("runroot")
+	}
+
 	if c.GlobalIsSet("storage-driver") {
 		options.GraphDriverName = c.GlobalString("storage-driver")
 	}
@@ -43,5 +52,18 @@ func findImage(store storage.Store, image string) (*storage.Image, error) {
 		img = img2
 	}
 	return img, nil
-
+}
+
+func getCopyOptions(reportWriter io.Writer) *cp.Options {
+	return &cp.Options{
+		ReportWriter: reportWriter,
+	}
+}
+
+func getSystemContext(signaturePolicyPath string) *types.SystemContext {
+	sc := &types.SystemContext{}
+	if signaturePolicyPath != "" {
+		sc.SignaturePolicyPath = signaturePolicyPath
+	}
+	return sc
 }

cmd/kpod/main.go

@@ -4,6 +4,7 @@ import (
 	"os"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/containers/storage/pkg/reexec"
 	"github.com/urfave/cli"
 )
 
@@ -11,6 +12,10 @@ import (
 const Version string = "0.0.1"
 
 func main() {
+	if reexec.Init() {
+		return
+	}
+
 	app := cli.NewApp()
 	app.Name = "kpod"
 	app.Usage = "manage pods and images"
@@ -20,6 +25,25 @@ func main() {
 		launchCommand,
 		tagCommand,
 		versionCommand,
+		pullCommand,
+	}
+	app.Flags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "root",
+			Usage: "path to the root directory in which data, including images,  is stored",
+		},
+		cli.StringFlag{
+			Name:  "runroot",
+			Usage: "path to the 'run directory' where all state information is stored",
+		},
+		cli.StringFlag{
+			Name:  "storage-driver, s",
+			Usage: "select which storage driver is used to manage storage of images and containers (default is overlay2)",
+		},
+		cli.StringSliceFlag{
+			Name:  "storage-opt",
+			Usage: "used to pass an option to the storage driver",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {

cmd/kpod/pull.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/Sirupsen/logrus"
+	cp "github.com/containers/image/copy"
+	"github.com/containers/image/docker/reference"
+	"github.com/containers/image/signature"
+	is "github.com/containers/image/storage"
+	"github.com/containers/image/transports/alltransports"
+	"github.com/containers/image/types"
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+const (
+	// DefaultRegistry is a prefix that we apply to an image name
+	// to check docker hub first for the image
+	DefaultRegistry = "docker://"
+)
+
+var (
+	pullFlags = []cli.Flag{
+		cli.BoolFlag{
+			// all-tags is hidden since it has not been implemented yet
+			Name:   "all-tags, a",
+			Hidden: true,
+			Usage:  "Download all tagged images in the repository",
+		},
+	}
+
+	pullDescription = "Pulls an image from a registry and stores it locally.\n" +
+		"An image can be pulled using its tag or digest. If a tag is not\n" +
+		"specified, the image with the 'latest' tag (if it exists) is pulled."
+	pullCommand = cli.Command{
+		Name:        "pull",
+		Usage:       "pull an image from a registry",
+		Description: pullDescription,
+		Flags:       pullFlags,
+		Action:      pullCmd,
+		ArgsUsage:   "",
+	}
+)
+
+// pullCmd gets the data from the command line and calls pullImage
+// to copy an image from a registry to a local machine
+func pullCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) == 0 {
+		logrus.Errorf("an image name must be specified")
+		return nil
+	}
+	if len(args) > 1 {
+		logrus.Errorf("too many arguments. Requires exactly 1")
+		return nil
+	}
+	image := args[0]
+
+	store, err := getStore(c)
+	if err != nil {
+		return err
+	}
+
+	allTags := false
+	if c.IsSet("all-tags") {
+		allTags = c.Bool("all-tags")
+	}
+
+	systemContext := getSystemContext("")
+
+	err = pullImage(store, image, allTags, systemContext)
+	if err != nil {
+		return errors.Errorf("error pulling image from %q: %v", image, err)
+	}
+	return nil
+}
+
+// pullImage copies the image from the source to the destination
+func pullImage(store storage.Store, imgName string, allTags bool, sc *types.SystemContext) error {
+	defaultName := DefaultRegistry + imgName
+	var fromName string
+	var tag string
+
+	srcRef, err := alltransports.ParseImageName(defaultName)
+	if err != nil {
+		srcRef2, err2 := alltransports.ParseImageName(imgName)
+		if err2 != nil {
+			return errors.Wrapf(err2, "error parsing image name %q", imgName)
+		}
+		srcRef = srcRef2
+	}
+
+	ref := srcRef.DockerReference()
+	if ref != nil {
+		imgName = srcRef.DockerReference().Name()
+		fromName = imgName
+		tagged, ok := srcRef.DockerReference().(reference.NamedTagged)
+		if ok {
+			imgName = imgName + ":" + tagged.Tag()
+			tag = tagged.Tag()
+		}
+	}
+
+	destRef, err := is.Transport.ParseStoreReference(store, imgName)
+	if err != nil {
+		return errors.Wrapf(err, "error parsing full image name %q", imgName)
+	}
+
+	policy, err := signature.DefaultPolicy(sc)
+	if err != nil {
+		return err
+	}
+
+	policyContext, err := signature.NewPolicyContext(policy)
+	if err != nil {
+		return err
+	}
+
+	fmt.Println(tag + ": pulling from " + fromName)
+
+	return cp.Image(policyContext, destRef, srcRef, getCopyOptions(os.Stdout))
+}

completions/bash/kpod

@@ -33,7 +33,7 @@ _kpod_version() {
      local boolean_options="
      "
      _complete_ "$options_with_args" "$boolean_options"
- }
+}
 
 kpod_tag() {
     local options_with_args="
@@ -43,6 +43,15 @@ kpod_tag() {
     _complete_ "$options_with_args" "$boolean_options"
 }
 
+_kpod_pull() {
+    local options_with_args="
+    "
+    local boolean_options="
+    --all-tags -a
+    "
+    _complete_ "$options_with_args" "$boolean_options"
+}
+
 _kpod_kpod() {
      local options_with_args="
      "
@@ -54,6 +63,7 @@ _kpod_kpod() {
 	launch
     tag
     version
+    pull
      "
 
      case "$prev" in

docs/kpod-pull.1.md

@@ -0,0 +1,39 @@
+% kpod(8) # kpod-pull - Simple tool to pull an image from a registry
+% Urvashi Mohnani
+% JULY 2017
+# NAME
+kpod-pull - Pull an image from a registry
+
+# SYNOPSIS
+**kpod pull**
+**NAME[:TAG|@DISGEST]**
+[**--help**|**-h**]
+
+# DESCRIPTION
+Copies an image from a registry onto the local machine. **kpod pull** pulls an
+image from Docker Hub if a registry is not specified in the command line argument.
+If an image tag is not specified, **kpod pull** defaults to the image with the
+**latest** tag (if it exists) and pulls it. **kpod pull** can also pull an image
+using its digest **kpod pull [image]@[digest]**.
+
+**kpod [GLOBAL OPTIONS]**
+
+**kpod pull [GLOBAL OPTIONS]**
+
+**kpod pull NAME[:TAG|@DIGEST] [GLOBAL OPTIONS]**
+
+# GLOBAL OPTIONS
+
+**--help, -h**
+  Print usage statement
+
+# COMMANDS
+
+## pull
+Pull an image from a registry
+
+# SEE ALSO
+kpod(1), crio(8), crio.conf(5)
+
+# HISTORY
+July 2017, Originally compiled by Urvashi Mohnani <umohnani@redhat.com>

test/kpod.bats

@@ -2,8 +2,48 @@
 
 load helpers
 
+ROOT="$TESTDIR/crio"
+RUNROOT="$TESTDIR/crio-run"
+KPOD_OPTIONS="--root $ROOT --runroot $RUNROOT --storage-driver vfs"
+
 @test "kpod version test" {
 	run ${KPOD_BINARY} version
 	echo "$output"
 	[ "$status" -eq 0 ]
 }
+
+@test "kpod pull from docker with tag" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull debian:6.0.10
+	echo "$output"
+	[ "$status" -eq 0 ]
+}
+
+@test "kpod pull from docker without tag" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull debian
+	echo "$output"
+	[ "$status" -eq 0 ]
+}
+
+@test "kpod pull from a non-docker registry with tag" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull registry.fedoraproject.org/fedora:rawhide
+	echo "$output"
+	[ "$status" -eq 0 ]
+}
+
+@test "kpod pull from a non-docker registry without tag" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull registry.fedoraproject.org/fedora
+	echo "$output"
+	[ "$status" -eq 0 ]
+}
+
+@test "kpod pull using digest" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull debian@sha256:7d067f77d2ae5a23fe6920f8fbc2936c4b0d417e9d01b26372561860750815f0
+	echo "$output"
+	[ "$status" -eq 0 ]
+}
+
+@test "kpod pull from a non existent image" {
+	run ${KPOD_BINARY} $KPOD_OPTIONS pull umohnani/get-started
+	echo "$output"
+	[ "$status" -ne 0 ]
+}