adds help for load command (#383)

* adds help for load command

Signed-off-by: Mike Brown <brownwm@us.ibm.com>

* vendor restrom/dedent

Signed-off-by: Mike Brown <brownwm@us.ibm.com>

cmd/cri-containerd/cri_containerd.go

@@ -26,11 +26,13 @@ import (
 	"os/signal"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"syscall"
 
 	"github.com/docker/docker/pkg/reexec"
 	"github.com/golang/glog"
 	"github.com/opencontainers/selinux/go-selinux"
+	"github.com/renstrom/dedent"
 	"github.com/spf13/cobra"
 	"golang.org/x/net/context"
 	"k8s.io/kubernetes/pkg/util/interrupt"
@@ -58,6 +60,30 @@ var cmd = &cobra.Command{
 	Long:  desc,
 }
 
+var (
+	loadLong = dedent.Dedent(`
+		Help for "load TAR" command
+
+		TAR - The path to a tar archive containing a container image.
+
+		Requirement:
+			Containerd and cri-containerd daemons (grpc servers) must already be up and
+			running before the load command is used.
+
+		Description:
+			Running as a client, cri-containerd implements the load command by sending the
+			load request to the already running cri-containerd daemon/server, which in
+			turn loads the image into containerd's image storage via the already running
+			containerd daemon.`)
+
+	loadExample = dedent.Dedent(`
+		- use docker to pull the latest busybox image and save it as a tar archive:
+			$ docker pull busybox:latest
+			$ docker save busybox:latest -o busybox.tar
+		- use cri-containerd to load the image into containerd's image storage:
+			$ cri-containerd load busybox.tar`)
+)
+
 // Add golang flags as persistent flags.
 func init() {
 	cmd.PersistentFlags().AddGoFlagSet(flag.CommandLine)
@@ -85,10 +111,13 @@ func versionCommand() *cobra.Command {
 
 func loadImageCommand() *cobra.Command {
 	c := &cobra.Command{
-		Use:   "load TAR",
+		Use:     "load TAR",
-		Short: "Load an image from a tar archive.",
+		Long:    loadLong,
-		Args:  cobra.ExactArgs(1),
+		Short:   "Load an image from a tar archive.",
+		Args:    cobra.ExactArgs(1),
+		Example: loadExample,
 	}
+	c.SetUsageTemplate(strings.Replace(c.UsageTemplate(), "Examples:", "Example:", 1))
 	endpoint, timeout := options.AddGRPCFlags(c.Flags())
 	c.RunE = func(cmd *cobra.Command, args []string) error {
 		cl, err := client.NewCRIContainerdClient(*endpoint, *timeout)

pkg/client/client.go

@@ -29,14 +29,14 @@ import (
 // NewCRIContainerdClient creates grpc client of cri-containerd
 // TODO(random-liu): Wrap grpc functions.
 func NewCRIContainerdClient(endpoint string, timeout time.Duration) (api.CRIContainerdServiceClient, error) {
-	addr, dailer, err := util.GetAddressAndDialer(endpoint)
+	addr, dialer, err := util.GetAddressAndDialer(endpoint)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get dialer: %v", err)
 	}
 	conn, err := grpc.Dial(addr,
 		grpc.WithInsecure(),
 		grpc.WithTimeout(timeout),
-		grpc.WithDialer(dailer),
+		grpc.WithDialer(dialer),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to dial: %v", err)

vendor.conf

@@ -47,7 +47,8 @@ github.com/pkg/errors v0.8.0
 github.com/pmezard/go-difflib v1.0.0
 github.com/PuerkitoBio/purell v1.0.0
 github.com/PuerkitoBio/urlesc 5bd2802263f21d8788851d5305584c82a5c75d7e
-github.com/seccomp/libseccomp-golang 32f571b70023028bd57d9288c20efbcb237f3ce0 
+github.com/renstrom/dedent 020d11c3b9c0c7a3c2efcc8e5cf5b9ef7bcea21f
+github.com/seccomp/libseccomp-golang 32f571b70023028bd57d9288c20efbcb237f3ce0
 github.com/sirupsen/logrus v1.0.0
 github.com/spf13/cobra v0.0.1
 github.com/spf13/pflag v1.0.0

vendor/github.com/renstrom/dedent/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Peter Renström
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/github.com/renstrom/dedent/README.md

@@ -0,0 +1,50 @@
+# Dedent
+
+[![Build Status](https://travis-ci.org/renstrom/dedent.svg?branch=master)](https://travis-ci.org/renstrom/dedent)
+[![Godoc](https://img.shields.io/badge/godoc-reference-blue.svg?style=flat)](https://godoc.org/github.com/renstrom/dedent)
+
+Removes common leading whitespace from multiline strings. Inspired by [`textwrap.dedent`](https://docs.python.org/3/library/textwrap.html#textwrap.dedent) in Python.
+
+## Usage / example
+
+Imagine the following snippet that prints a multiline string. You want the indentation to both look nice in the code as well as in the actual output.
+
+```go
+package main
+
+import (
+    "fmt"
+
+    "github.com/renstrom/dedent"
+)
+
+func main() {
+    s := `Lorem ipsum dolor sit amet,
+        consectetur adipiscing elit.
+        Curabitur justo tellus, facilisis nec efficitur dictum,
+        fermentum vitae ligula. Sed eu convallis sapien.`
+    fmt.Println(dedent.Dedent(s))
+    fmt.Println("-------------")
+    fmt.Println(s)
+}
+```
+
+To illustrate the difference, here's the output:
+
+
+```bash
+$ go run main.go
+Lorem ipsum dolor sit amet,
+consectetur adipiscing elit.
+Curabitur justo tellus, facilisis nec efficitur dictum,
+fermentum vitae ligula. Sed eu convallis sapien.
+-------------
+Lorem ipsum dolor sit amet,
+        consectetur adipiscing elit.
+        Curabitur justo tellus, facilisis nec efficitur dictum,
+        fermentum vitae ligula. Sed eu convallis sapien.
+```
+
+## License
+
+MIT

vendor/github.com/renstrom/dedent/dedent.go

@@ -0,0 +1,49 @@
+package dedent
+
+import (
+	"regexp"
+	"strings"
+)
+
+var (
+	whitespaceOnly    = regexp.MustCompile("(?m)^[ \t]+$")
+	leadingWhitespace = regexp.MustCompile("(?m)(^[ \t]*)(?:[^ \t\n])")
+)
+
+// Dedent removes any common leading whitespace from every line in text.
+//
+// This can be used to make multiline strings to line up with the left edge of
+// the display, while still presenting them in the source code in indented
+// form.
+func Dedent(text string) string {
+	var margin string
+
+	text = whitespaceOnly.ReplaceAllString(text, "")
+	indents := leadingWhitespace.FindAllStringSubmatch(text, -1)
+
+	// Look for the longest leading string of spaces and tabs common to all
+	// lines.
+	for i, indent := range indents {
+		if i == 0 {
+			margin = indent[1]
+		} else if strings.HasPrefix(indent[1], margin) {
+			// Current line more deeply indented than previous winner:
+			// no change (previous winner is still on top).
+			continue
+		} else if strings.HasPrefix(margin, indent[1]) {
+			// Current line consistent with and no deeper than previous winner:
+			// it's the new winner.
+			margin = indent[1]
+		} else {
+			// Current line and previous winner have no common whitespace:
+			// there is no margin.
+			margin = ""
+			break
+		}
+	}
+
+	if margin != "" {
+		text = regexp.MustCompile("(?m)^"+margin).ReplaceAllString(text, "")
+	}
+	return text
+}