Merge pull request #737 from umohnani8/kpod_export

Add 'kpod export' command

cmd/kpod/export.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"io"
+	"os"
+
+	"fmt"
+
+	"github.com/containers/storage"
+	"github.com/containers/storage/pkg/archive"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli"
+)
+
+type exportOptions struct {
+	output    string
+	container string
+}
+
+var (
+	exportFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "output, o",
+			Usage: "Write to a file, default is STDOUT",
+			Value: "/dev/stdout",
+		},
+	}
+	exportDescription = "Exports container's filesystem contents as a tar archive" +
+		" and saves it on the local machine."
+	exportCommand = cli.Command{
+		Name:        "export",
+		Usage:       "Export container's filesystem contents as a tar archive",
+		Description: exportDescription,
+		Flags:       exportFlags,
+		Action:      exportCmd,
+		ArgsUsage:   "CONTAINER",
+	}
+)
+
+// exportCmd saves a container to a tarball on disk
+func exportCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) == 0 {
+		return errors.Errorf("container id must be specified")
+	}
+	if len(args) > 1 {
+		return errors.Errorf("too many arguments given, need 1 at most.")
+	}
+	container := args[0]
+
+	config, err := getConfig(c)
+	if err != nil {
+		return errors.Wrapf(err, "could not get config")
+	}
+	store, err := getStore(config)
+	if err != nil {
+		return err
+	}
+
+	output := c.String("output")
+	if output == "/dev/stdout" {
+		file := os.Stdout
+		if logrus.IsTerminal(file) {
+			return errors.Errorf("refusing to export to terminal. Use -o flag or redirect")
+		}
+	}
+
+	opts := exportOptions{
+		output:    output,
+		container: container,
+	}
+
+	return exportContainer(store, opts)
+}
+
+// exportContainer exports the contents of a container and saves it as
+// a tarball on disk
+func exportContainer(store storage.Store, opts exportOptions) error {
+	mountPoint, err := store.Mount(opts.container, "")
+	if err != nil {
+		return errors.Wrapf(err, "error finding container %q", opts.container)
+	}
+	defer func() {
+		if err := store.Unmount(opts.container); err != nil {
+			fmt.Printf("error unmounting container %q: %v\n", opts.container, err)
+		}
+	}()
+
+	input, err := archive.Tar(mountPoint, archive.Uncompressed)
+	if err != nil {
+		return errors.Wrapf(err, "error reading container directory %q", opts.container)
+	}
+
+	outFile, err := os.Create(opts.output)
+	if err != nil {
+		return errors.Wrapf(err, "error creating file %q", opts.output)
+	}
+	defer outFile.Close()
+
+	_, err = io.Copy(outFile, input)
+	return err
+}

cmd/kpod/main.go

@@ -22,6 +22,7 @@ func main() {
 	app.Version = Version
 
 	app.Commands = []cli.Command{
+		exportCommand,
 		historyCommand,
 		imagesCommand,
 		infoCommand,

completions/bash/kpod

@@ -182,6 +182,15 @@ _kpod_save() {
      _complete_ "$options_with_args" "$boolean_options"
 }
 
+_kpod_export() {
+     local options_with_args="
+     --output -o
+     "
+     local boolean_options="
+     "
+     _complete_ "$options_with_args" "$boolean_options"
+}
+
 _complete_() {
     local options_with_args=$1
     local boolean_options="$2 -h --help"

docs/kpod-export.1.md

@@ -0,0 +1,48 @@
+% kpod(1) kpod-export - Simple tool to export a container's filesystem as a tarball
+% Urvashi Mohnani
+# kpod-export "1" "July 2017" "kpod"
+
+## NAME
+kpod-export - Export container's filesystem contents as a tar archive
+
+## SYNOPSIS
+**kpod export**
+**CONTAINER**
+[**--help**|**-h**]
+
+## DESCRIPTION
+**kpod export** exports the filesystem of a container and saves it as a tarball
+on the local machine. **kpod export** writes to STDOUT by default and can be
+redirected to a file using the **output flag**.
+
+**kpod [GLOBAL OPTIONS]**
+
+**kpod export [GLOBAL OPTIONS]**
+
+**kpod export [OPTIONS] CONTAINER [GLOBAL OPTIONS]**
+
+## OPTIONS
+
+**--output, -o**
+Write to a file, default is STDOUT
+
+## GLOBAL OPTIONS
+
+**--help, -h**
+  Print usage statement
+
+## EXAMPLES
+
+```
+# kpod export -o redis-container.tar 883504668ec465463bc0fe7e63d53154ac3b696ea8d7b233748918664ea90e57
+```
+
+```
+# kpod export > redis-container.tar 883504668ec465463bc0fe7e63d53154ac3b696ea8d7b233748918664ea90e57
+```
+
+## SEE ALSO
+kpod(1), kpod-import(1), crio(8), crio.conf(5)
+
+## HISTORY
+August 2017, Originally compiled by Urvashi Mohnani <umohnani@redhat.com>

test/kpod_export.bats

@@ -0,0 +1,35 @@
+#!/usr/bin/env bats
+
+load helpers
+
+IMAGE="redis:alpine"
+ROOT="$TESTDIR/crio"
+RUNROOT="$TESTDIR/crio-run"
+KPOD_OPTIONS="--root $ROOT --runroot $RUNROOT ${STORAGE_OPTS}"
+
+
+@test "kpod export output flag" {
+    start_crio
+    [ "$status" -eq 0 ]
+    run crioctl pod run --config "$TESTDATA"/sandbox_config.json
+    echo "$output"
+    [ "$status" -eq 0 ]
+    pod_id="$output"
+    run crioctl image pull "$IMAGE"
+    [ "$status" -eq 0 ]
+    run crioctl ctr create --config "$TESTDATA"/container_config.json --pod "$pod_id"
+    echo "$output"
+    [ "$status" -eq 0 ]
+    ctr_id="$output"
+    run ${KPOD_BINARY} ${KPOD_OPTIONS} export -o container.tar "$ctr_id"
+    echo "$output"
+    [ "$status" -eq 0 ]
+    cleanup_ctrs
+    [ "$status" -eq 0 ]
+    cleanup_pods
+    [ "$status" -eq 0 ]
+    stop_crio
+    [ "$status" -eq 0 ]
+    rm -f container.tar
+    [ "$status" -eq 0 ]
+}